This is an approximate grouping. Remember that a turtle-related primitive might still be called by patches or observers, and vice versa. To see which agent (turtles, patches, observer) can actually run each command, consult each individual entry in the dictionary.
back (bk) <breeds>-at <breeds>-here <breeds>-on can-move? clear-turtles (ct) create-<breeds> create-custom-<breeds> create-custom-turtles (cct) create-turtles (crt) die distance distancexy downhill downhill4 dx dy face facexy forward (fd) hatch hatch-<breeds> hide-turtle (ht) home inspect is-<breed>? is-turtle? jump left (lt) myself nobody -of other-turtles-here other-<breeds>-here patch-ahead patch-at-heading-and-distance patch-here patch-left-and-ahead patch-right-and-ahead pen-down (pd) pen-erase (pe) pen-up (pu) random-xcor random-ycor right (rt) self set-default-shape __set-line-thickness setxy shapes show-turtle (st) sprout sprout-<breeds> stamp stamp-erase subject subtract-headings __tie towards towardsxy turtle turtles turtles-at turtles-from turtles-here turtles-on turtles-own __untie uphill value-from
clear-patches (cp) diffuse diffuse4 distance distancexy import-pcolors inspect is-patch? myself neighbors neighbors4 nobody nsum nsum4 -of patch patch-at patch-ahead patch-at-heading-and-distance patch-here patch-left-and-ahead patch-right-and-ahead patches patches-from patches-own random-pxcor random-pycor self sprout sprout-<breeds> subject value-from
any? ask at-points <breeds>-at <breeds>-here <breeds>-on count histogram-from in-cone in-radius is-agent? is-agentset? is-patch-agentset? is-turtle-agentset? max-one-of min-one-of n-of neighbors neighbors4 one-of other-turtles-here other-<breeds>-here patches patches-from sort sort-by turtles with with-max with-min turtles-at turtles-from turtles-here turtles-on values-from
color extract-hsb extract-rgb hsb import-pcolors pcolor rgb scale-color shade-of? wrap-color
and carefully end error-message foreach if ifelse ifelse-value let loop map not or repeat report run runresult ; (semicolon) set stop startup to to-report wait while without-interruption xor
clear-all (ca) clear-drawing (cd) clear-patches (cp) clear-turtles (ct) display import-drawing import-pcolors no-display max-pxcor max-pycor min-pxcor min-pycor world-width world-height
follow follow-me reset-perspective (rp) ride ride-me subject watch watch-me
hubnet-broadcast hubnet-broadcast-view hubnet-enter-message? hubnet-exit-message? hubnet-fetch-message hubnet-message hubnet-message-source hubnet-message-tag hubnet-message-waiting? hubnet-reset hubnet-send hubnet-send-view hubnet-set-client-interface
beep clear-output date-and-time export-view export-interface export-output export-plot export-all-plots export-world import-drawing import-pcolors import-world mouse-down? mouse-inside? mouse-xcor mouse-ycor output-print output-show output-type output-write print read-from-string reset-timer set-current-directory show timer type user-directory user-file user-new-file user-input user-message user-one-of user-yes-or-no? write
file-at-end? file-close file-close-all file-delete file-exists? file-open file-print file-read file-read-characters file-read-line file-show file-type file-write user-directory user-file user-new-file
but-first but-last empty? filter first foreach fput is-list? item last length list lput map member? modes n-of n-values position one-of reduce remove remove-duplicates remove-item replace-item reverse sentence shuffle sort sort-by sublist values-from
Operators (+, <, >, =, !=, <=, >=) but-first but-last empty? first is-string? item last length member? position remove remove-item read-from-string replace-item reverse substring word
Arithmetic Operators (+, *, -, /, ^, <, >, =, !=, <=, >=) abs acos asin atan ceiling cos e exp floor int ln log max mean median min mod modes new-seed pi precision random random-exponential random-float random-gamma random-int-or-float random-normal random-poisson random-seed remainder round sin sqrt standard-deviation subtract-headings sum tan variance
autoplot? auto-plot-off auto-plot-on clear-all-plots clear-plot create-temporary-plot-pen export-plot export-all-plots histogram-from histogram-list plot plot-name plot-pen-down (ppd) plot-pen-reset plot-pen-up (ppu) plot-x-max plot-x-min plot-y-max plot-y-min plotxy ppd ppu set-current-plot set-current-plot-pen set-histogram-num-bars set-plot-pen-color set-plot-pen-interval set-plot-pen-mode set-plot-x-range set-plot-y-range
__both-ends __create-<breed>-from __create-<breeds>-from __create-<breed>-to __create-<breeds>-to __create-<breed>-with __create-<breeds>-with __end1 __end2 __in-<breed>-neighbor? __in-<breed>-neighbors __in-<breed>-from __is-link? __layout-circle __layout-magspring __layout-radial __layout-spring __layout-tutte __<breed>-neighbor? __<breed>-neighbors __<breed>-with __my-<breeds> __my-in-<breeds> __my-out-<breeds> __other-end __out-<breed>-neighbor? __out-<breed>-neighbors __out-<breed>-to __remove-<breed>-from __remove-<breeds>-from __remove-<breed>-to __remove-<breeds>-to __remove-<breed>-with __remove-<breeds>-with
movie-cancel movie-close movie-grab-view movie-grab-interface movie-set-frame-rate movie-start movie-status
breed color heading hidden? label label-color pen-mode pen-size shape size who xcor ycor
pcolor plabel plabel-color pxcor pycor
breed end globals patches-own to to-report turtles-own
e = 2.718281828459045
pi = 3.141592653589793
false
true
black = 0.0
gray = 5.0
white = 9.9
red = 15.0
orange = 25.0
brown = 35.0
yellow = 45.0
green = 55.0
lime = 65.0
turquoise = 75.0
cyan = 85.0
sky = 95.0
blue = 105.0
violet = 115.0
magenta = 125.0
pink = 135.0
See the Colors section of the Programming Guide for more details.
Reports the absolute value of number.
show abs -7 => 7 show abs 5 => 5
Reports the arc cosine (inverse cosine) of the given number. The input must be in the range -1.0 to 1.0. The result is in degrees, and lies in the range 0.0 to 180.0.
Reports true if both condition1 and condition2 are true.
Note that if condition1 is false, then condition2 will not be run (since it can't affect the result).
if (pxcor > 0) and (pycor > 0)
[ set pcolor blue ] ;; the upper-right quadrant of
;; patches turn blue
Reports true if the given agentset is non-empty, false otherwise.
Equivalent to "count agentset > 0", but arguably more readable.
if any? turtles with [color = red] [ show "at least one turtle is red!" ]
Note: "nobody" is not an agentset. You only get nobody back in situations where you were expecting a single agent, not a whole agentset. If any? gets nobody as input, an error results.
See also nobody.
All of these operators take two inputs, and all act as "infix operators" (going between the two inputs, as in standard mathematical use). NetLogo correctly supports order of operations for infix operators.
The operators work as follows: + is addition, * is multiplication, - is subtraction, / is division, ^ is exponentiation, < is less than, > is greater than, = is equal to, != is not equal to, <= is less than or equal, >= is greater than or equal.
Note that the subtraction operator (-) always takes two inputs unless you put parentheses around it, in which case it can take one input. For example, to take the negative of x, write (- x), with the parentheses.
All of the comparison operators also work on strings, and the addition operator (+) also functions as a string concatenation operator (see example below).
If you are not sure how NetLogo will interpret your code, you should insert parentheses.
show 5 * 6 + 6 / 3 => 32 show 5 * (6 + 6) / 3 => 20 show "tur" + "tle" => "turtle"
Reports the arc sine (inverse sine) of the given number. The input must be in the range -1.0 to 1.0. The result is in degrees, and lies in the range -90.0 to 90.0.
The specified agent or agentset runs the given commands.
ask turtles [ fd 1 ] ;; all turtles move forward one step ask patches [ set pcolor red ] ;; all patches turn red ask turtle 4 [ rt 90 ] ;; only the turtle with id 4 turns right
Note: only the observer can ask all turtles or all patches. This prevents you from inadvertently having all turtles ask all turtles or all patches ask all patches, which is a common mistake to make if you're not careful about which agents will run the code you are writing.
Note: Only the agents that are in the agentset at the time the ask begins run the commands.
Reports a subset of the given agentset that includes only the agents on the patches the given distances away from the calling agent. The distances are specified as a list of two-item lists, where the two items are the x and y offsets.
If the caller is the observer, then the points are measured relative to the origin, in other words, the points are taken as absolute patch coordinates.
If the caller is a turtle, the points are measured relative to the turtle's exact location, and not from the center of the patch under the turtle.
ask turtles at-points [[2 4] [1 2] [10 15]]
[ fd 1 ] ;; only the turtles on the patches at the
;; distances (2,4), (1,2) and (10,15),
;; relative to the caller, move
Reports the arc tangent, in degrees (from 0 to 360), of x divided by y.
When y is 0: if x is positive, it reports 90; if x is negative, it reports 270; if x is zero, you get an error.
Note that this version of atan is designed to conform to the geometry of the NetLogo world, where a heading of 0 is straight up, 90 is to the right, and so on clockwise around the circle. (Normally in geometry an angle of 0 is right, 90 is up, and so on, counterclockwise around the circle, and atan would be defined accordingly.)
show atan 1 -1 => 135.0 show atan -1 1 => 315.0
Reports true if auto-plotting is on for the current plot, false otherwise.
This pair of commands is used to control the NetLogo feature of auto-plotting in the current plot. Auto-plotting will automatically update the x and y axes of the plot whenever the current pen exceeds these boundaries. It is useful when wanting to display all plotted values in the current plot, regardless of the current plot ranges.
The turtle moves backward by number steps. (If number is negative, the turtle moves forward.)
Turtles using this primitive can move a maximum of one unit per time increment. So bk 0.5 and bk 1 both take one unit of time, but bk 3 takes three.
If the turtle cannot move backward number steps because it is not permitted by the current topology the turtle will complete as many steps of 1 as it can and stop.
See also forward, jump, can-move?.
Emits a beep. Note that the beep is emitted immediately, so several beep commands in succession will only produce a single audible sound.
Example:
beep ;; emits one beep
repeat 3 [ beep ] ;; emits 3 beeps at the exact same time,
;; so you only hear one sound
repeat 3 [ beep wait 0.1 ] ;; produces 3 beeps in succession,
;; separated by 1/10th of a second
Reports the agentset of the 2 nodes connected by this link turtle.
;; Let a directed link turtle L be connected from N1 to N2. ask L [ show __both-ends ;; displays an agentset consisting of N1 and N2. ]
This reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
This is a built-in turtle variable. It holds the agentset of all turtles of the same breed as this turtle. (For turtles that do not have any particular breed, this is the turtles agentset of all turtles.) You can set this variable to change a turtle's breed.
See also breed.
Example:
breed [cats cat] breed [dogs dog] ;; turtle code: if breed = cats [ show "meow!" ] set breed dogs show "woof!"
This keyword, like the globals, turtles-own, and patches-own keywords, can only be used at the beginning of the Procedures tab, before any procedure definitions. It defines a breed. The first input defines the name of the agentset associated with the breed. The second input defines the name of a single member of the breed.
Any turtle of the given breed:
Most often, the agentset is used in conjunction with ask to give commands to only the turtles of a particular breed.
breed [mice mouse] breed [frogs frog] to setup ca create-mice 50 ask mice [ set color white ] create-frogs 50 ask frogs [ set color green ] show breed-of one-of mice ;; prints mice show breed-of one-of frogs ;; prints frogs end show mouse 1 ;; prints (mouse 1) show frog 51 ;; prints (frog 51) show turtle 51 ;; prints (frog 51)
See also globals, patches-own, turtles-own, <breeds>-own, create-<breeds>, create-custom-<breeds>, <breeds>-at, <breeds>-here.
When used on a list, but-first reports all of the list items of list except the first, and but-last reports all of the list items of list except the last.
On strings, but-first and but-last report a shorter string omitting the first or last character of the original string.
;; mylist is [2 4 6 5 8 12] set mylist but-first mylist ;; mylist is now [4 6 5 8 12] set mylist but-last mylist ;; mylist is now [4 6 8] show but-first "string" ;; prints "tring" show but-last "string" ;; prints "strin"
Reports true if the calling turtle can move distance in the direction it is facing without violating the topology; reports false otherwise.
It is equivalent to:
patch-ahead distance != nobody
Runs commands1. If a runtime error occurs inside commands1, NetLogo won't stop and alert the user that an error occurred. It will suppress the error and run commands2 instead.
The error-message reporter can be used in commands2 to find out what error was suppressed in commands1. See error-message.
Note: both sets of commands run without interruption (as with the without-interruption command).
carefully [ show 1 / 1 ] [ print error-message ] => 1 carefully [ show 1 / 0 ] [ print error-message ] => division by zero
Reports the smallest integer greater than or equal to number.
show ceiling 4.5 => 5 show ceiling -4.5 => -4
Resets all global variables to zero, and calls clear-turtles, clear-patches, clear-drawing, clear-all-plots, and clear-output.
Clears every plot in the model. See clear-plot for more information.
Clears all lines and stamps drawn by turtles.
Clears all text from the model's output area, if it has one. Otherwise does nothing.
Clears the patches by resetting all patch variables to their default initial values, including setting their color to black.
In the current plot only, resets all plot pens, deletes all temporary plot pens, resets the plot to its default values (for x range, y range, etc.), and resets all permanent plot pens to their default values. The default values for the plot and for the permanent plot pens are set in the plot Edit dialog, which is displayed when you edit the plot. If there are no plot pens after deleting all temporary pens, that is to say if there are no permanent plot pens, a default plot pen will be created with the following initial settings:
See also clear-all-plots.
Kills all turtles.
See also die.
This is a built-in turtle variable. It holds the color of the turtle. You can set this variable to make the turtle change color.
See also pcolor.
Reports the cosine of the given angle. Assumes the angle is given in degrees.
show cos 180 => -1.0
Reports the number of agents in the given agentset.
show count turtles ;; prints the total number of turtles show count patches with [pcolor = red] ;; prints the total number of red patches
Used for creating link turtles between agents. Links are special turtles. A link turtle's size is always equal to the distance between the two node turtles it links together. Its heading is always equal to the heading from one node turtle to the other. Its location is always halfway between the two node turtles. Their default shape is "link".
__create-<breed>-with creates an undirected link between the caller and agent. __create-<breed>-to creates a link from the caller to agent. __create-<breed>-from creates a link from agent to the caller.
When the plural form of the breed name is used, an agentset is expected instead of an agent and links are created between the caller and all agents in the agentset.
The command block is the set of commands each newly formed link runs. (The links are created all at once then run one at a time, in random order.)
A node cannot be linked to itself. Also, you cannot have more than one undirected link of the same breed between the same two nodes, nor can you have more than one directed link of the same breed going in the same direction between two nodes.
breed [links link] ;; breed for network links
to make-friend [ frd ] ;; node procedure
;; creates a friendship link between
;; the node on which this
;; procedure was called and the node "frd".
__create-link-to frd
[
set color blue
]
end
to become-friendly ;; node procedure
;; makes this node link with an agentset of turtles
__create-links-to friends
[]
end
This command is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Creates number new turtles . New turtles start at position (0, 0), are created with the 14 primary colors, and have headings from 0 to 360, evenly spaced.
crt 100 ask turtles [ fd 10 ] ;; makes an evenly spaced circle
If the create-<breeds> form is used, the new turtles are created as members of the given breed.
Creates number new turtles (of the given breed, if specified). New turtles start at position (0, 0). New turtles are created with the 14 primary colors and have headings from 0 to 360, evenly spaced.
The new turtles immediately run commands. This is useful for giving the new turtles a different color, heading, or whatever. (The new turtles are created all at once then run one at a time, in random order.)
breed [canaries canary]
breed [snakes snake]
to setup
ca
create-custom-canaries 50
[ set color yellow ]
create-custom-snakes 50
[ set color green ]
end
Note: While the commands are running, no other agents are allowed to run any code (as with the without-interruption command). This ensures that the new turtles cannot interact with any other agents until they are fully initialized. In addition, no display updates take place until the commands are done. This ensures that the new turtles are never drawn in the view until they are fully initialized.
A new temporary plot pen with the given name is created in the current plot and set to be the current pen.
Few models will want to use this primitive, because all temporary pens disappear when clear-plot or clear-all-plots are called. The normal way to make a pen is to make a permanent pen in the plot's Edit dialog.
If a temporary pen with that name already exists in the current plot, no new pen is created, and the existing pen is set to the the current pen. If a permanent pen with that name already exists in the current plot, you get a runtime error.
The new temporary plot pen has the following initial settings:
See: clear-plot, clear-all-plots, and set-current-plot-pen.
Reports a string containing the current date and time. The format is shown below. All fields are fixed width, so they are always at the same locations in the string. The potential resolution of the clock is milliseconds. (Whether you get resolution that high in practice may vary from system to system, depending on the capabilities of the underlying Java Virtual Machine.)
show date-and-time => "01:19:36.685 PM 19-Sep-2002"
The turtle dies.
if xcor > 20 [ die ]
;; all turtles with xcor greater than 20 die
See also: ct
Tells each patch to share (number * 100) percent of the value of patch-variable with its eight neighboring patches. number should be between 0 and 1. Regardless of topology the sum of patch-variable will be conserved across the world. If a patch has fewer than eight neighbors the remainder stays on the patch at the edge of the world.
Note that this is an observer command only, even though you might expect it to be a patch command. (The reason is that it acts on all the patches at once -- patch commands act on individual patches.)
diffuse chemical 0.5 ;; each patch diffuses 50% of its variable ;; chemical to its neighboring 8 patches. Thus, ;; each patch gets 1/8 of 50% of the chemical ;; from each neighboring patch.)
Like diffuse, but only diffuses to the four neighboring patches (to the north, south, east, and west), not to the diagonal neighbors.
diffuse4 chemical 0.5 ;; each patch diffuses 50% of its variable ;; chemical to its neighboring 4 patches. Thus, ;; each patch gets 1/4 of 50% of the chemical ;; from each neighboring patch.)
Causes the current view to be updated immediately.
Also undoes the effect of the no-display command, so that if display updates were suspended by that command, they will resume.
no-display ask turtles [ jump 10 set color blue set size 5 ] display ;; turtles move, change color, and grow, with none of ;; their intermediate states visible to the user, only ;; their final state
Even if no-display was not used, "display" can still be useful, because ordinarily NetLogo is free to skip some view updates, so that fewer total updates take place, so that models run faster. This command lets you force a view update, so whatever changes have taken place in the world are visible to the user.
ask turtles [ set color red ] display ask turtles [ set color blue] ;; turtles turn red, then blue; use of "display" forces ;; red turtles to appear briefly
There is exception to the "immediately" rule: if the command is used by an agent that is running "without interruption" (such as via the without-interruption command, inside a procedure defined using to-report, or inside a command such as hatch, sprout, or cct), then the view update takes place once the agent is done running without interruption.
Note that display and no-display operate independently of the switch in the view control strip that freezes the view.
See also no-display.
Reports the distance from this agent to the given turtle or patch.
The distance to or a from a patch is measured from the center of the patch. Turtles and patches use the wrapped distance (around the edges of the view) if wrapping is allowed by the topology and the wrapped distance is shorter than the on-screen distance.
Reports the distance from this agent to the point (xcor, ycor).
The distance from a patch is measured from the center of the patch. Turtles and patches use the wrapped distance (around the edges of the view) if wrapping is allowed by the topology and the wrapped distance is shorter than the on-screen distance.
if (distancexy 0 0) > 10 [ set color green ] ;; all turtles more than 10 units from ;; the center of the screen turn green.
Reports the turtle heading (between 0 and 359 degrees) in the direction of the minimum value of the variable patch-variable, of the patches in a one-patch radius of the turtle. (This could be as many as eight patches or as few as one patch, depending on the position of the turtle within its patch and the topology of the world.)
If there are multiple patches that have the same smallest value, a random one of those patches will be selected.
If the patch is located directly to the north, south, east, or west of the patch that the turtle is currently on, a multiple of 90 degrees is reported. However, if the patch is located to the northeast, northwest, southeast, or southwest of the patch that the turtle is currently on, the direction the turtle would need to reach the nearest corner of that patch is reported.
See also downhill4, uphill, uphill4.
Reports the turtle heading (between 0 and 359 degrees) as a multiple of 90 degrees in the direction of the minimum value of the variable patch-variable, of the four patches to the north, south, east, and west of the turtle. If there are multiple patches that have the same least value, a random patch from those patches will be selected.
See also downhill, uphill, uphill4.
Reports the x-increment or y-increment (the amount by which the turtle's xcor or ycor would change) if the turtle were to take one step forward in its current heading.
Note: dx is simply the sine of the turtle's heading, and dy is simply the cosine. (If this is the reverse of what you expected, it's because in NetLogo a heading of 0 is north and 90 is east, which is the reverse of how angles are usually defined in geometry.)
Note: In earlier versions of NetLogo, these primitives were used in many situations where the new patch-ahead primitive is now more appropriate.
Reports true if the given list or string is empty, false otherwise.
Note: the empty list is written []. The empty string is written "".
Used to conclude a procedure. See to and to-report.
Reports the first end of a link. In a directed link, the direction of the link is from end1 to the end2.
;; Let a directed link L be connected from N1 to N2. ask L [ show __end1 ;; prints N1 ]
Even though in an undirected link order of nodes is not important, end1 is deterministic and reports the same node on repeated calls by an undirected link.
This reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Reports the second end of a link. In a directed link, the direction of the link is from end1 to the end2.
;; Let a directed link L be connected from N1 to N2. ask L [ show __end2 ;; prints N2 ]
Even though in an undirected link order of nodes is not important, end2 is deterministic and reports the same node from repeated calls by an undirected link.
This reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Reports a string describing the error that was suppressed by carefully.
This reporter can only be used in the second block of a carefully command.
See also carefully.
Runs the given commands at most every number seconds.
By itself, every doesn't make commands run over and over again. You need to use every inside a loop, or inside a forever button, if you want the commands run over and over again. every only limits how often the commands run.
More technically, its exact behavior is as follows. When an agent reaches an "every", it checks a timer to see if the given amount of time has passed since the last time the same agent ran the commands in the "every" in the same context. If so, it runs the commands; otherwise they are skipped and execution continues.
Here, "in the same context" means during the same ask (or button press or command typed in the Command Center). So it doesn't make sense to write ask turtles [ every 0.5 [ ... ] ], because when the ask finishes the turtles will all discard their timers for the "every". The correct usage is shown below.
every 0.5 [ ask turtles [ fd 1 ] ] ;; twice a second the turtles will move forward 1 every 2 [ set index index + 1 ] ;; every 2 seconds index is incremented
See also wait.
Reports the value of e raised to the number power.
Note: This is the same as e ^ number.
export-view writes the current contents of the current view to an external file given by the string filename. The file is saved in PNG (Portable Network Graphics) format, so it is recommended to supply a filename ending in ".png".
export-interface is similar, but for the whole interface tab.
export-output writes the contents of the model's output area to an external file given by the string filename. (If the model does not have a separate output area, the output portion of the Command Center is used.)
export-plot writes the x and y values of all points plotted by all the plot pens in the plot given by the string plotname to an external file given by the string filename. If a pen is in bar mode (mode 0) and the y value of the point plotted is greater than 0, the upper-left corner point of the bar will be exported. If the y value is less than 0, then the lower-left corner point of the bar will be exported.
export-all-plots writes every plot in the current model to an external file given by the string filename. Each plot is identical in format to the output of export-plot.
export-world writes the values of all variables, both built-in and user-defined, including all observer, turtle, and patch variables, the drawing, and the contents of the output area if one exists, to an external file given by the string filename. (The result file can be read back into NetLogo with the import-world primitive.)
export-plot, export-all-plots and export-world save files in in plain-text, "comma-separated values" (.csv) format. CSV files can be read by most popular spreadsheet and database programs as well as any text editor.
If the file already exists, it is overwritten.
If you wish to export to a file in a location other than the model's location, you should include the full path to the file you wish to export. (Use the forward-slash "/" as the folder separator.)
Note that the functionality of these primitives is also available directly from NetLogo's File menu.
export-world "fire.csv" ;; exports the state of the model to the file fire.csv ;; located in the NetLogo folder export-plot "Temperature" "c:/My Documents/plot.csv" ;; exports the plot named ;; "Temperature" to the file plot.csv located in ;; the C:\My Documents folder export-all-plots "c:/My Documents/plots.csv" ;; exports all plots to the file plots.csv ;; located in the C:\My Documents folder
Reports a list of three values in the range 0.0 to 1.0 representing the hue, saturation and brightness, respectively, of the given NetLogo color in the range 0 to 140.
show extract-hsb red => [0.0090 0.809 0.843] show extract-hsb cyan => [0.5 0.571 0.769]
See also hsb, rgb, extract-rgb.
Reports a list of three values in the range 0.0 to 1.0 representing the levels of red, green, and blue, respectively, of the given NetLogo color in the range 0 to 140.
show extract-rgb red => [0.843 0.196 0.161] show extract-rgb cyan => [0.329 0.769 0.769]
See also rgb, hsb, extract-hsb.
Set the caller's heading towards agent.
If wrapping is allowed by the topology and the wrapped distance (around the edges of the view) is shorter than the on-screen distance, face will use the heading of the wrapped path.
If the caller and the agent are at the exact same position, the caller's heading won't change.
Set the caller's heading towards the point (x,y).
If wrapping is allowed by the topology and the wrapped distance (around the edges of the view) is shorter than the on-screen distance and wrapping is allowed, facexy will use the heading of the wrapped path.
If the caller is on the point (x,y), the caller's heading won't change.
Reports true when there are no more characters left to read in from the current file (that was opened previously with file-open). Otherwise, reports false.
file-open "myfile.txt" print file-at-end? => false ;; Can still read in more characters print file-read-line => This is the last line in file print file-at-end => true ;; We reached the end of the file
See also file-open, file-close-all.
Closes a file that has been opened previously with file-open.
Note that this and file-close-all are the only ways to restart to the beginning of an opened file or to switch between file modes.
If no file is open, does nothing.
See also file-close-all, file-open.
Closes all files (if any) that have been opened previously with file-open.
See also file-close, file-open.
Deletes the file specified as string
string must be an existing file with writable permission by the user. Also, the file cannot be open. Use the command file-close to close an opened file before deletion.
Note that the string can either be a file name or an absolute file path. If it is a file name, it looks in whatever the current directory is. This can be changed using the command set-current-directory. It is defaulted to the model's directory.
Reports true if string is the name of an existing file on the system. Otherwise it reports false.
Note that the string can either be a file name or an absolute file path. If it is a file name, it looks in whatever the current directory is. This can be changed using the command set-current-directory. It defaults to to the model's directory.
This command will interpret string as a path name to a file and open the file. You may then use the reporters file-read, file-read-line, and file-read-characters to read in from the file, or file-write, file-print, file-type, or file-show to write out to the file.
Note that you can only open a file for reading or writing but not both. The next file i/o primitive you use after this command dictates which mode the file is opened in. To switch modes, you need to close the file using file-close.
Also, the file must already exist if opening a file in reading mode.
When opening a file in writing mode, all new data will be appended to the end of the original file. If there is no original file, a new blank file will be created in its place. (You must have write permission in the file's directory.) (If you don't want to append, but want to replace the file's existing contents, use file-delete to delete it first, perhaps inside a carefully if you're not sure whether it already exists.)
Note that the string can either be a file name or an absolute file path. If it is a file name, it looks in whatever the current directory is. This can be changed using the command set-current-directory. It is defaulted to the model's directory.
file-open "myfile-in.txt" print file-read-line => First line in file ;; File is in reading mode file-open "C:\\NetLogo\\myfile-out.txt" ;; assuming Windows machine file-print "Hello World" ;; File is in writing mode
See also file-close.
Prints value to an opened file, followed by a carriage return.
The calling agent is not printed before the value, unlike file-show.
Note that this command is the file i/o equivalent of print, and file-open needs to be called before this command can be used.
See also file-show, file-type, and file-write.
This reporter will read in the next constant from the opened file and interpret it as if it had been typed in the Command Center. It reports the resulting value. The result may be a number, list, string, boolean, or the special value nobody.
Whitespace separates the constants. Each call to file-read will skip past both leading and trailing whitespace.
Note that strings need to have quotes around them. Use the command file-write to have quotes included.
Also note that the file-open command must be called before this reporter can be used, and there must be data remaining in the file. Use the reporter file-at-end? to determine if you are at the end of the file.
file-open "myfile.data" print file-read + 5 ;; Next value is the number 1 => 6 print length file-read ;; Next value is the list [1 2 3 4] => 4
See also file-open and file-write.
Reports the given number of characters from an opened file as a string. If there are fewer than that many characters left, it will report all of the remaining characters.
Note that it will return every character including newlines and spaces.
Also note that the file-open command must be called before this reporter can be used, and there must be data remaining in the file. Use the reporter file-at-end? to determine if you are at the end of the file.
file-open "myfile.txt" print file-read-characters 8 ;; Current line in file is "Hello World" => Hello Wo
See also file-open.
Reads the next line in the file and reports it as a string. It determines the end of the file by a carriage return, an end of file character or both in a row. It does not return the line terminator characters.
Also note that the file-open command must be called before this reporter can be used, and there must be data remaining in the file. Use the reporter file-at-end? to determine if you are at the end of the file.
file-open "myfile.txt" print file-read-line => Hello World
See also file-open.
Prints value to an opened file, preceded by the calling agent, and followed by a carriage return. (The calling agent is included to help you keep track of what agents are producing which lines of output.) Also, all strings have their quotes included similar to file-write.
Note that this command is the file i/o equivalent of show, and file-open needs to be called before this command can be used.
See also file-print, file-type, and file-write.
Prints value to an opened file, not followed by a carriage return (unlike file-print and file-show). The lack of a carriage return allows you to print several values on the same line.
The calling agent is not printed before the value. unlike file-show.
Note that this command is the file i/o equivalent of type, and file-open needs to be called before this command can be used.
See also file-print, file-show, and file-write.
This command will output value, which can be a number, string, list, boolean, or nobody to an opened file not followed by a carriage return (unlike file-print and file-show).
The calling agent is not printed before the value, unlike file-show. Its output also includes quotes around strings and is prepended with a space. It will output the value in such a manner that file-read will be able to interpret it.
Note that this command is the file i/o equivalent of write, and file-open needs to be called before this command can be used.
file-open "locations.txt" ask turtles [ file-write xcor file-write ycor ]
See also file-print, file-show, and file-type.
Reports a list containing only those items of list for which the boolean reporter is true -- in other words, the items satisfying the given condition.
In reporter, use ? to refer to the current item of list.
show filter [? < 3] [1 3 2] => [1 2] show filter [first ? != "t"] ["hi" "there" "everyone"] => ["hi" "everyone"]
On a list, reports the first (0th) item in the list.
On a string, reports a one-character string containing only the first character of the original string.
Reports the largest integer less than or equal to number.
show floor 4.5 => 4 show floor -4.5 => -5
Similar to ride, but, in the 3D view, the view is behind and above turtle.
See also follow-me, ride, reset-perspective, watch, subject.
Asks the observer to follow the calling turtle.
See also follow.
With a single list, runs commands for each item of list. In commands, use ? to refer to the current item of list.
foreach [1.1 2.2 2.6] [ show ? + " -> " + round ? ] => 1.1 -> 1 => 2.2 -> 2 => 2.6 -> 3
With multiple lists, runs commands for each group of items from each list. So, they are run once for the first items, once for the second items, and so on. All the lists must be the same length. In commands, use ?1 through ?n to refer to the current item of each list.
Some examples make this clearer:
(foreach [1 2 3] [2 4 6] [ show "the sum is: " + (?1 + ?2) ]) => "the sum is: 3" => "the sum is: 6" => "the sum is: 9" (foreach list (turtle 1) (turtle 2) [3 4] [ ask ?1 [ fd ?2 ] ]) ;; turtle 1 moves forward 3 patches ;; turtle 2 moves forward 4 patches
The turtle moves forward by number steps. (If number is negative, the turtle moves backward.)
Turtles using this primitive can move a maximum of one unit per turn. So fd 0.5 and fd 1 both take one turn, but fd 3 takes three.
If the turtle cannot move forward number steps because it is not permitted by the current topology the turtle will complete as many steps of 1 as it can, then stop.
Adds item to the beginning of a list and reports the new list.
;; suppose mylist is [5 7 10] set mylist fput 2 mylist ;; mylist is now [2 5 7 10]
This keyword, like the breed, <breeds>-own, patches-own, and turtles-own keywords, can only be used at the beginning of a program, before any function definitions. It defines new global variables. Global variables are "global" because they are accessible by all agents and can be used anywhere in a model.
Most often, globals is used to define variables or constants that need to be used in many parts of the program.
This turtle creates number new turtles, each identical to its parent, and asks the new turtles to run commands. You can use the commands to give the new turtles different colors, headings, or whatever. (The new turtles are created all at once, then run one at a time, in random order.)
If the hatch-<breeds> form is used, the new turtles are created as members of the given breed. Otherwise, the new turtles are the same breed as their parent.
Note: While the commands are running, no other agents are allowed to run any code (as with the without-interruption command). This ensures that the new turtles cannot interact with any other agents until they are fully initialized. In addition, no display updates take place until the commands are done. This ensures that the new turtles are never drawn in an partly initialized state.
hatch 1 [ lt 45 fd 1 ] ;; this turtle creates one new turtle, ;; and the child turns and moves away hatch-sheep 1 [ set color black ] ;; this turtle creates a new turtle ;; of the sheep breed
This is a built-in turtle variable. It indicates the direction the turtle is facing. This is a number greater than or equal to 0 and less than 360. 0 is north, 90 is east, and so on. You can set this variable to make a turtle turn.
Example:
set heading 45 ;; turtle is now facing northeast set heading heading + 10 ;; same effect as "rt 10"
This is a built-in turtle variable. It holds a boolean (true or false) value indicating whether the turtle is currently hidden (i.e., invisible). You can set this variable to make a turtle disappear or reappear.
See also hide-turtle, show-turtle.
Example:
set hidden? not hidden? ;; if turtle was showing, it hides, and if it was hiding, ;; it reappears
The turtle makes itself invisible.
Note: This command is equivalent to setting the turtle variable "hidden?" to true.
See also show-turtle.
Draws a histogram showing the frequency distribution of the values reported when all agents in the agentset run the given reporter. The heights of the bars in the histogram represent the numbers of agents with values in those ranges.
Before the histogram is drawn, first any previous points drawn by the current plot pen are removed.
The reporter should report a numeric value. Any non-numeric values reported are ignored.
The histogram is drawn on the current plot using the current plot pen and pen color. Use set-plot-x-range to control the range of values to be histogrammed, and set the pen interval (either directly with set-plot-pen-interval, or indirectly via set-histogram-num-bars) to control how many bars that range is split up into.
Be sure that if you want the histogram drawn with bars that the current pen is in bar mode (mode 1).
As of NetLogo 2.0.2, for histogramming purposes the plot's X range is not considered to include the maximum X value. Values equal to the maximum X will fall outside of the histogram's range.
histogram-from turtles [color] ;; draws a histogram showing how many turtles there are ;; of each color
Note: using this primitive amounts to the same thing as writing: histogram-list values-from agentset [ reporter ], but is more efficient.
Histograms the values in the given list, after first removing any previous points drawn by the current plot pen.
See histogram-from, above, for more information.
The calling turtles moves to the origin (0,0). Equivalent to setxy 0 0.
Reports a number in the range 0 to 140, not including 140 itself, that represents the given color, specified in the HSB spectrum, in NetLogo's color space.
All three values should be in the range 0.0 to 1.0.
The color reported may be only an approximation, since the NetLogo color space does not include all possible colors. (It contains only certain discrete hues, and for each hue, either saturation or brightness may vary, but not both -- at least one of the two is always 1.0.)
show hsb 0 0 0 => 0.0 ;; (black) show hsb 0.5 1.0 1.0 => 85.0 ;; (cyan)
See also extract-hsb, rgb, extract-rgb.
This broadcasts value from NetLogo to the variable, in the case of Calculator HubNet, or interface element, in the case of Computer HubNet, with the name tag-name to the clients.
See the HubNet Authoring Guide for details and instructions.
This broadcasts the current state of the 2D view in the NetLogo model to all the Computer HubNet Clients. It does nothing for Calculator HubNet.
Note: This is an experimental primitive and its behavior may change in a future version.
See the HubNet Authoring Guide for details and instructions.
Reports true if a new computer client just entered the simulation. Reports false otherwise. hubnet-message-source will contain the user name of the client that just logged on.
See the HubNet Authoring Guide for details and instructions.
Reports true if a computer client just exited the simulation. Reports false otherwise. hubnet-message-source will contain the user name of the client that just logged off.
See the HubNet Authoring Guide for details and instructions.
If there is any new data sent by the clients, this retrieves the next piece of data, so that it can be accessed by hubnet-message, hubnet-message-source, and hubnet-message-tag. This will cause an error if there is no new data from the clients.
See the HubNet Authoring Guide for details.
Reports the message retrieved by hubnet-fetch-message.
See the HubNet Authoring Guide for details.
Reports the name of the client that sent the message retrieved by hubnet-fetch-message.
See the HubNet Authoring Guide for details.
Reports the tag that is associated with the data that was retrieved by hubnet-fetch-message. For Calculator HubNet, this will report one of the variable names set with the hubnet-set-client-interface primitive. For Computer HubNet, this will report one of the Display Names of the interface elements in the client interface.
See the HubNet Authoring Guide for details.
This looks for a new message sent by the clients. It reports true if there is one, and false if there is not.
See the HubNet Authoring Guide for details.
Starts up the HubNet system. HubNet must be started to use any of the other hubnet primitives with the exception of hubnet-set-client-interface.
See the HubNet Authoring Guide for details.
For Calculator HubNet, this primitive acts in exactly the same manner as hubnet-broadcast. (We plan to change this in a future version of NetLogo.)
For Computer HubNet, it acts as follows:
For a string, this sends value from NetLogo to the tag tag-name on the client that has string for its user name.
For a list-of-strings, this sends value from NetLogo to the tag tag-name on all the clients that have a user name that is in the list-of-strings.
Sending a message to a non-existent client, using hubnet-send, generates a hubnet-exit-message.
See the HubNet Authoring Guide for details.
For Calculator HubNet, does nothing.
For Computer HubNet, it acts as follows:
For a string, this sends the current state of the 2D view in the NetLogo model to the Computer HubNet Client with string for its user name.
For a list-of-strings, this sends the current state of the view in the NetLogo model to all the Computer HubNet Clients that have a user name that is in the list-of-strings.
Sending the 2D view to a non-existent client, using hubnet-send-view, generates a hubnet-exit-message.
Note: This is an experimental primitive and its behavior may change in a future version.
See the HubNet Authoring Guide for details.
If client-type is "COMPUTER", client-info is a list containing a string with the file name and path (relative to the model) to the file which will serve as the client's interface. This interface will be sent to any clients that log in.
hubnet-set-client-interface "COMPUTER" ["clients/Disease client.nlogo"] ;; when clients log in, they will will get the ;; interface described in the file ;; clients/Disease client.nlogo, relative to ;; the location of the model
Future versions of HubNet will support other client types. Even for Computer HubNet, the meaning of the second input to this command may change.
See the HubNet Authoring Guide for details.
Reporter must report a boolean (true or false) value.
If condition reports true, runs commands.
The reporter may report a different value for different agents, so some agents may run commands and others don't.
if xcor > 0[ set color blue ] ;; turtles on the right half of the view ;; turn blue
See also ifelse, ifelse-value.
Reporter must report a boolean (true or false) value.
If reporter reports true, runs commands1.
If reporter reports false, runs commands2.
The reporter may report a different value for different agents, so some agents may run commands1 while others run commands2.
ask patches
[ ifelse pxcor > 0
[ set pcolor blue ]
[ set pcolor red ] ]
;; the left half of the view turns red and
;; the right half turns blue
See also if, ifelse-value.
Reporter must report a boolean (true or false) value.
If reporter reports true, the result is the value of reporter1.
If reporter reports false, the result is the value of reporter2.
This can be used when a conditional is needed in the context of a reporter, where commands (such as ifelse) are not allowed.
ask patches
[ set pcolor
ifelse-value (pxcor > 0)
[ blue ]
[ red ] ]
;; the left half of the view turns red and
;; the right half turns blue
show n-values 10 [ifelse-value (? < 5) [0] [1]]
=> [0 0 0 0 0 1 1 1 1 1]
show reduce [ifelse-value (?1 > ?2) [?1] [?2]]
[1 3 2 5 3 8 3 2 1]
=> 8
Reads an image file into the drawing, scaling it to the size of the world, while retaining the original aspect ratio of the image. The image is centered in the drawing. The old drawing is not cleared first.
Agents cannot sense the drawing, so they cannot interact with or process images imported by import-drawing. If you need agents to sense an image, use import-pcolors.
The following image file formats are supported: BMP, JPG, GIF, and PNG. If the image format supports transparency (alpha), that information will be imported as well.
Reads an image file, scales it to the same dimensions as the patch grid while maintaining the original aspect ratio of the image, and transfers the resulting pixel colors to the patches. The image is centered in the patch grid. The resulting patch colors may be distorted, since the NetLogo color space does not include all possible colors. (See the Color section of the Programming Guide.) import-pcolors may be slow for some images, particularly when you have many patches and a large image with many different colors.
Since import-pcolors sets the pcolor of patches, agents can sense the image. This is useful if agents need to analyze, process, or otherwise interact with the image. If you want to simply display a static backdrop, without color distortion, see import-drawing.
The following image file formats are supported: BMP, JPG, GIF, and PNG. If the image format supports transparency (alpha), then all fully transparent pixels will be ignored. (Partially transparent pixels will be treated as opaque.)
Reads the values of all variables for a model, both built-in and user-defined, including all observer, turtle, and patch variables, from an external file named by the given string. The file should be in the format used by the export-world primitive.
Note that the functionality of this primitive is also directly available from NetLogo's File menu.
When using import-world, to avoid errors, perform these steps in the following order:
If you wish to import a file from a location other than the model's location, you may include the full path to the file you wish to import. See export-world for an example.
This reporter lets you give a turtle a "cone of vision" in front of itself. The cone is defined by the two inputs, the vision distance (radius) and the view angle. The view angle may range from 0 to 360 and is centered around the turtle's current heading. (If the angle is 360, then in-cone is equivalent to in-radius.)
in-cone reports an agentset that includes only those agents from the original agentset that fall in the cone including the agent itself.
The distance to a patch is measured from the center of the patch.
ask turtles
[ ask patches in-cone 3 60
[ set pcolor red ] ]
;; each turtle makes a red "splotch" of patches in a 60 degree
;; cone of radius 3 ahead of itself
Reports true if there is a link going from agent to the caller.
to check-friendship-neighbors
ca
cct-turtles 2[]
ask turtle 0
[
__create-link-to turtle 1[]
show __in-link-neighbor? turtle 1 ;; prints false
show __out-link-neighbor? turtle 1 ;; prints true
]
ask turtle 1
[
show __in-link-neighbor? turtle 0 ;; prints true
show __out-link-neighbor? turtle 0 ;; prints false
]
end
This reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Reports the agentset of all the node turtles that have links coming from them to the caller.
breed [links link] ;; breed for network links to become-friendly ;; node procedure __create-links-to friends [] show __out-link-neighbors ;; prints the agentset of friends end
This reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Report the link turtle from the agent to the caller. If no link exists then it reports nobody.
to find-friendship-with
ca
cct 2 []
ask turtle 0
[
__create-link-to turtle 1 []
__create-link-from turtle 1 []
show __in-link-from turtle 1 ;; prints turtle 3
show __out-link-to turtle 1 ;; prints turtle 2
show __link-with turtle 1 ;; prints turtle 2
]
end
This reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Reports an agentset that includes only those agents from the original agentset whose distance from the caller is less than or equal to number, including the caller itself if wrapping is allowed by the topology members of the agentset within the radius using the wrapped distance will be included.
The distance to or a from a patch is measured from the center of the patch.
ask turtles
[ ask patches in-radius 3
[ set pcolor red ] ]
;; each turtle makes a red "splotch" around itself
Opens an agent monitor for the given agent (turtle or patch).
inspect patch 2 4 ;; an agent monitor opens for that patch inspect one-of sheep ;; an agent monitor opens for a random turtle from ;; the "sheep" breed
Reports the integer part of number -- any fractional part is discarded.
show int 4.7 => 4 show int -3.5 => -3
Reports true if value is of the given type, false otherwise.
On lists, reports the value of the item in the given list with the given index.
On strings, reports the character in the given string at the given index.
Note that the indices begin from 0, not 1. (The first item is item 0, the second item is item 1, and so on.)
;; suppose mylist is [2 4 6 8 10] show item 2 mylist => 6 show item 3 "my-shoe" => "s"
The __is-link? reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Turtles move forward by number units all at once, without the number of turns it takes depending on the distance.
This command is useful for synchronizing turtle movements. A turtle takes 15 turns to do fd 15, but only one turn to do jump 15.
If the turtle cannot jump number units because it is not permitted by the current topology the turtle does not move at all.
Note: When turtles jump, they do not step on any of the patches along their path.
This is a built-in turtle variable. It may hold a value of any type. The turtle appears in the view with the given value "attached" to it as text. You can set this variable to add, change, or remove a turtle's label.
See also label-color, plabel, plabel-color.
Example:
ask turtles [ set label who ] ;; all the turtles now are labeled with their ;; id numbers ask turtles [ set label "" ] ;; all turtles now are not labeled
This is a built-in turtle variable. It holds a number greater than or equal to 0 and less than 140. This number determines what color the turtle's label appears in (if it has a label). You can set this variable to change the color of a turtle's label.
See also label, plabel, plabel-color.
Example:
ask turtles [ set label-color red ] ;; all the turtles now have red labels
On a list, reports the last item in the list.
On a string, reports a one-character string containing only the last character of the original string.
Arranges the given turtles in a circle centered on the patch at the center of the world with the given radius. (If the world has an even size the center of the circle is rounded down to the nearest patch.) The turtles point outwards.
If the first input is an agentset, the turtles are arranged in random order.
If the first input is a list, the turtles are arranged clockwise in the given order, starting at the top of the circle. (Any non-turtles in the list are ignored.)
;; in random order __layout-circle turtles 10 ;; in order by who number __layout-circle sort turtles 10 ;; in order by size __layout-circle sort-by [size-of ?1 < size-of ?2] turtles 10
Very similar to __layout-spring, but with an added layer of complexity. The agentset of turtles attract and repel each other depending on the links between them, but there is also a magnetic field which the links try to align with.
anchor-agentset is a set of turtles whose positions remain fixed. (If no turtles are anchored down, then they will often all slide off to the side of the view!)
spring-constant is a measure of the "tautness" of the spring. (See __layout-spring)
spring-length is the "zero-force" length or the natural length of the springs. (See __layout-spring)
repulsion-constant is a measure of repulsion between the nodes. (See __layout-spring)
magnetic-field-strength is the force of the magnetic field. (Reasonable values range from 0.0 to 1.0, but 0.05 is a good default.)
magnetic-field-type is a number in the range from 0 to 10. Choices are listed in the table below.
| magnetic-field-type | Description |
| NONE = 0 | If no field is used, then this command works just like layout-spring. |
| NORTH = 1 | Magnetic field runs toward the North |
| NORTHEAST = 2 | Magnetic field runs toward the Northeast |
| EAST = 3 | ... |
| SOUTHEAST= 4 | ... |
| SOUTH = 5 | ... |
| SOUTHWEST= 6 | ... |
| WEST = 7 | ... |
| NORTHWEST = 8 | ... |
| POLAR = 9 | Magnetic field runs outward at all angles from the origin. |
| CONCENTRIC = 10 |
Magnetic field runs clockwise around the origin in concentric circles. |
If bidirectional? is true then links try to align with the magnetic field by pushing attached turtles both in the direction of the field, and in the opposite direction. Otherwise, the links just push in a single direction.
breed [links link]
breed[nodes node]
to make-a-tree
set-default-shape nodes "circle"
create-custom-nodes 5 []
ask turtle 0
[
__create-link-with turtle 1 []
__create-link-with turtle 2 []
]
ask turtle 1
[
__create-link-with turtle 3 []
__create-link-with turtle 4 []
]
; one turtle (the root of the tree) is our anchor-set
let anchor-set (turtles with [ who = 0])
; layout with a fairly strong SOUTH magnetic field
repeat 50 [ __layout-magspring
nodes anchor-set 0.3 4 1.0 .50 5 false ]
end
This command is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Arranges the agentset of turtles, agentset, in a radial tree layout, centered around root-agent.
Only links of the given breed will be used to determine the layout. (Useful if you have multiple link breeds in one model.)
Even if the network does contain cycles, and is not a true tree structure, this layout will still work, although the results will not always be pretty.
If agentset is an agentset of patches, an error is thrown.
breed [links link]
to make-a-tree
set-default-shape turtles "circle"
cct 6 []
ask turtle 0
[
__create-link-with turtle 1 []
__create-link-with turtle 2 []
__create-link-with turtle 3 []
]
ask turtle 1
[
__create-link-with turtle 4 []
__create-link-with turtle 5 []
]
; do a radial tree layout, centered on turtle 0
__layout-radial turtles (turtle 0) links
end
This command is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Arranges the agentset of turtles, agentset, as if the links with which they are connected to each other were springs and the nodes were repelling each other.
spring-constant is a measure of the "tautness" of the spring. It is the "resistance" to change in their length. spring-constant is the force the spring would exert if it's length were changed by 1 unit.
spring-length is the "zero-force" length or the natural length of the springs. This is the length which all springs try to achieve either by pushing out their nodes or pulling them in.
repulsion-constant is a measure of repulsion between the nodes. It is the force that 2 nodes at a distance of 1 unit will exert on each other.
The repulsion effect tries to get the nodes as far as possible from each other, in order to avoid crowding and the spring effect tries to keep them at "about" a certain distance from the nodes they are connected to. The result is the laying out of the whole network in a way which highlights relationships among the nodes and at the same time is crowded less and is visually pleasing.
If agentset is an agentset of patches, an error is thrown.
The layout algorithm is based on the Fruchterman-Reingold layout algorithm. More information about this algorithm can be obtained here.
breed [links link]
breed [nodes node]
to make-a-triangle
set-default-shape nodes "circle"
create-custom-nodes 3 []
ask turtle 0
[
__create-links-with turtles with [ who-of self != 0 ]
[]
]
ask turtle 1
[
__create-link-with turtle 2
[]
]
repeat 30 [__layout-spring nodes 0.2 5 1] ;; lays the nodes in a triangle
end
This command is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
The turtles in anchor-agentset are placed in a circle layout with the given radius. There should be at least 3 agents in the anchor-agentset.
The turtles in agentset (unless they are also members of anchor-agentset) are then laid out in the following manner: Each turtle is placed at centroid (or barycenter) of the polygon formed by its linked neighbors. (The centroid is like a 2-dimensional average of the coordinates of the neighbors.)
(The purpose of the circle of anchor-agentset is to prevent all the turtles from collapsing down to one point.)
After a few iterations of this, the layout will stabilize.
If agentset is an agentset of patches, an error is thrown.
This layout is named after the mathematician William Thomas Tutte, who proposed it as a method for graph layout.
breed [links link ]
to make-a-tree
set-default-shape turtles "circle"
cct 6 []
ask turtle 0
[
__create-link-with turtle 1 []
__create-link-with turtle 2 []
__create-link-with turtle 3 []
]
ask turtle 1
[
__create-link-with turtle 4 []
__create-link-with turtle 5 []
]
; place all the turtles with just one
; neighbor on the perimeter of a circle
; and then place the remaining turtles inside
; this circle, spread between their neighbors.
repeat 10 [ __layout-tutte turtles
(turtles with [ count __link-neighbors = 1]) 12.0 ]
end
This command is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
The turtle turns left by number degrees. (If number is negative, it turns right.)
Reports the number of items in the given list, or the number of characters in the given string.
Creates a new local variable and gives it the given value. A local variable is one that exists only within the enclosing block of commands.
If you want to change the value afterwards, use set.
Example:
let prey one-of sheep-here if prey != nobody [ ask prey [ die ] ]
Reports a list containing the given items. The items can be of any type, produced by any kind of reporter.
show list (random 10) (random 10) => [4 9] ;; or similar list show (list 5) => [5] show (list (random 10) 1 2 3 (random 10)) => [4 1 2 3 9] ;; or similar list
Reports the natural logarithm of number, that is, the logarithm to the base e (2.71828...).
NOTE: This keyword should not be used in new models. Please use the let command instead. "locals" is included only for backwards compatibility with NetLogo version 2.0 and earlier. It will not necessarily continue to be supported in future versions of NetLogo.
Locals is a keyword used to declare "local" variables in a procedure, that is, variables that are usable only within that procedure. It must appear at the beginning of the procedure, before any commands.
See also let.
Reports the logarithm of number in base base.
show log 64 2 => 6
See also ln.
Runs the list of commands forever, or until the current procedure exits through use of the stop command or the report command.
Note: In most circumstances, you should use a forever button in order to repeat something forever. The advantage of using a forever button is that the user can click the button to stop the loop.
Adds value to the end of a list and reports the new list.
;; suppose mylist is [2 7 10 "Bob"] set mylist lput 42 mylist ;; mylist now is [2 7 10 "Bob" 42]
With a single list, the given reporter is run for each item in the list, and a list of the results is collected and reported.
In reporter, use ? to refer to the current item of list.
show map [round ?] [1.1 2.2 2.7] => [1 2 3] show map [? * ?] [1 2 3] => [1 4 9]
With multiple lists, the given reporter is run for each group of items from each list. So, it is run once for the first items, once for the second items, and so on. All the lists must be the same length.
In reporter, use ?1 through ?n to refer to the current item of each list.
Some examples make this clearer:
show (map [?1 + ?2] [1 2 3] [2 4 6]) => [3 6 9] show (map [?1 + ?2 = ?3] [1 2 3] [2 4 6] [3 5 9]) => [true false true]
Reports the maximum number value in the list. It ignores other types of items.
show max values-from turtles [xcor] ;; prints the x coordinate of the turtle which is ;; farthest right in the view
Reports the agent in the agentset that has the highest value for the given reporter. If there is a tie this command reports one random agent with the highest value. If you want all such agents, use with-max instead.
show max-one-of patches [count turtles-here]
;; prints the first patch with the most turtles on it
See also with-max
These reporters give the maximum x-coordinate and maximum y-coordinate, (respectively) for patches, which determines the size of the world.
Unlike in older versions of NetLogo the origin does not have to be at the center of the world. However, the maximum x- and y- coordinates must be greater than or equal to zero.
Note: You can set the size of the world only by editing the view -- these are reporters which cannot be set.
cct 100 [ setxy random-float max-pxcor
random-float max-pycor ]
;; distributes 100 turtles randomly in the
;; first quadrant
See also min-pxcor, min-pycor, world-width, and world-height
Reports the statistical mean of the numeric items in the given list. Ignores non-numeric items. The mean is the average, i.e., the sum of the items divided by the total number of items.
show mean values-from turtles [xcor] ;; prints the average of all the turtles' x coordinates
Reports the statistical median of the numeric items of the given list. Ignores non-numeric items. The median is the item that would be in the middle if all the items were arranged in order. (If two items would be in the middle, the median is the average of the two.)
show median values-from turtles [xcor] ;; prints the median of all the turtles' x coordinates
For a list, reports true if the given value appears in the given list, otherwise reports false.
For a string, reports true or false depending on whether string1 appears anywhere inside string2 as a substring.
For an agentset, reports true if the given agent is appears in the given agentset, otherwise reports false.
show member? 2 [1 2 3] => true show member? 4 [1 2 3] => false show member? "rin" "string" => true show member? turtle 0 turtles => true show member? turtle 0 patches => false
See also position.
Reports the minimum number value in the list. It ignores other types of items.
show min values-from turtles [xcor] ;; prints the lowest x-coordinate of all the turtles
Reports a random agent in the agentset that reports the lowest value for the given reporter. If there is a tie, this command reports one random agent that meets the condition. If you want all such agents use with-min instead.
show min-one-of turtles [xcor + ycor] ;; reports the first turtle with the smallest sum of ;; coordinates
See also with-min
These reporters give the minimum x-coordinate and minimum y-coordinate, (respectively) for patches, which determines the size of the world.
Unlike in older versions of NetLogo the origin does not have to be at the center of the world. However, the minimum x- and y- coordinates must be less than or equal to zero.
Note: You can set the size of the world only by editing the view -- these are reporters which cannot be set.
cct 100 [ setxy random-float min-pxcor
random-float min-pycor ]
;; distributes 100 turtles randomly in the
;; third quadrant
See also max-pxcor, max-pycor, world-width, and world-height
Reports number1 modulo number2: that is, the residue of number1 (mod number2). mod is is equivalent to the following NetLogo code:
number1 - (floor (number1 / number2)) * number2
Note that mod is "infix", that is, it comes between its two inputs.
show 62 mod 5 => 2 show -8 mod 3 => 1
See also remainder. mod and remainder behave the same for positive numbers, but differently for negative numbers.
Reports a list of the most common item or items in list.
The input list may contain any NetLogo values.
If the input is an empty list, reports an empty list.
show modes [1 2 2 3 4] => [2] show modes [1 2 2 3 3 4] => [2 3] show modes [ [1 2 [3]] [1 2 [3]] [2 3 4] ] => [[1 2 [3]] show modes values-from turtles [pxcor] ;; shows which columns of patches have the most ;; turtles on them
Reports true if the mouse button is down, false otherwise.
Note: If the mouse pointer is outside of the current view , mouse-down? will always report false.
Reports true if the mouse pointer is inside the current view, false otherwise.
Reports the x or y coordinate of the mouse in the 2D view. The value is in terms of turtle coordinates, so it is a floating-point number. If you want patch coordinates, use round mouse-xcor and round mouse-ycor.
Note: If the mouse is outside of the 2D view, reports the value from the last time it was inside.
;; to make the mouse "draw" in red: if mouse-down? [ set pcolor-of patch-at mouse-xcor mouse-ycor red ]
Cancels the current movie.
Stops the recording of the current movie.
Adds an image of the current view or the interface panel to the current movie.
;; make a 20-step movie of the current view setup movie-start "out.mov" repeat 20 [ movie-grab-view go ] movie-close
Sets the frame rate of the current movie. The frame rate is measured in frames per second. (If you do not explicitly set the frame rate, it defaults to 15 frames per second.)
Must be called after movie-start, but before movie-grab-view or movie-grab-interface.
See also movie-status.
Creates a new movie. filename specifies a new QuickTime file
where the movie will be saved, so it should end with ".mov".
See also movie-grab-view, movie-grab-interface, movie-cancel, movie-status, movie-set-frame-rate, movie-close.
Reports a string describing the current movie.
print movie-status => No movie. movie-start print movie-status => 0 frames; Framerate = 15.0. movie-grab-view print movie-status 1 frames; Framerate = 15.0; Size = 315x315.
Reports an agentset of all links coming in from other nodes to the caller.
breed [links link] ;; breed for network links
to become-friendly ;; node procedure
__create-links-with other-turtles
[]
show __my-links ;; prints the agentset of link turtles that connecting
;; with this node.
end
This reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Reports an agentset of all the directed links coming in from other nodes to the caller.
breed [links link] ;; breed for network links
to become-friendly ;; node procedure
__create-links-to other-turtles
[]
show __my-in-links ;; prints the agentset of link turtles that connect
;; to this node
end
This reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Reports an agentset of all the directed links going out from the caller to other nodes.
breed [links link] ;; breed for network links
to become-friendly ;; node procedure
__create-links-to other-turtles
[]
show __my-out-links ;; prints the agentset of link turtles that connect
;; from this node
end
This reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
"self" and "myself" are very different. "self" is simple; it means "me". "myself" means "the turtle or patch who asked me to do what I'm doing right now."
When an agent has been asked to run some code, using myself in that code reports the agent (turtle or patch) that did the asking.
myself is most often used in conjunction with -of to read or set variables in the asking agent.
myself can be used within blocks of code not just in the ask command, but also hatch, sprout, values-from, value-from, turtles-from, patches-from, histogram-from, with, min-one-of, and max-one-of.
ask turtles
[ ask patches in-radius 3
[ set pcolor color-of myself ] ]
;; each turtle makes a colored "splotch" around itself
See the "Myself Example" code example for more examples.
See also self.
From an agentset, reports an agentset of size size randomly chosen from the input set, with no repeats.
From a list, reports a list of size size randomly chosen from the input set, with no repeats. The items in the result appear in the same order that they appeared in the input list. (If you want them in random order, use shuffle on the result.)
It is an error for size to be greater than the size of the input.
ask n-of 50 patches [ set pcolor green ] ;; 50 randomly chosen patches turn green
See also one-of.
Reports a list of length size containing values computed by repeatedly running reporter.
In reporter, use ? to refer to the number of the item currently being computed, starting from zero.
show n-values 5 [1] => [1 1 1 1 1] show n-values 5 [?] => [0 1 2 3 4] show n-values 3 [turtle ?] => [(turtle 0) (turtle 1) (turtle 2)] show n-values 5 [? * ?] => [0 1 4 9 16]
Reports an agentset containing the 8 surrounding patches (neighbors) or 4 surrounding patches (neighbors4).
show sum values-from neighbors [count turtles-here] ;; prints the total number of turtles on the eight ;; patches around the calling turtle or patch ask neighbors4 [ set pcolor red ] ;; turns the four neighboring patches red
Reports the agentset of all the node turtles that have links coming from them to the caller, or coming from the caller to them.
breed [links link] ;; breed for network links
to become-friendly ;; node procedure
__create-links-to friends
[]
show __link-neighbors ;; prints the agentset of agents who are
;; "friends" with, or whom it is "friends" with
end
This reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Reports true if there is a link going from agent to the caller, or from the caller to agent.
to check-friendship-neighbors
ca
cct-turtles 2[]
ask turtle 0
[
__create-link-to turtle 1[]
show __in-link-neighbor? turtle 1 ;; prints false
show __out-link-neighbor? turtle 1 ;; prints true
show __link-neighbor? turtle 1 ;; prints true
]
ask turtle 1
[
show __in-link-neighbor? turtle 0 ;; prints true
show __out-link-neighbor? turtle 0 ;; prints false
show __link-neighbor? turtle 0 ;; prints true
]
end
This reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Reports a string containing the version number of the NetLogo you are running.
show netlogo-version => "3.1.5"
Reports a number suitable for seeding the random number generator.
The numbers reported by new-seed are based on the current date and time in milliseconds and lie in the range -2147483648 to 2147483647.
new-seed never reports the same number twice in succession. (This is accomplished by waiting a millisecond if the seed for the current millisecond was already used.)
See also random-seed.
Turns off all updates to the current view until the display command is issued. This has two major uses.
One, you can control when the user sees view updates. You might want to change lots of things on the view behind the user's back, so to speak, then make them visible to the user all at once.
Two, your model will run faster when view updating is off, so if you're in a hurry, this command will let you get results faster. (Note that normally you don't need to use no-display for this, since you can also use the on/off switch in view control strip to freeze the view.)
Note that display and no-display operate independently of the switch in the view control strip that freezes the view.
See also display.
This is a special value which some primitives such as turtle, one-of, max-one-of, etc. report to indicate that no agent was found. Also, when a turtle dies, it becomes equal to nobody.
Note: Empty agentsets are not equal to nobody. If you want to test for an empty agentset, use any?. You only get nobody back in situations where you were expecting a single agent, not a whole agentset.
set other one-of other-turtles-here if other != nobody [ set color-of other red ]
Reports true if boolean is false, otherwise reports false.
if not (color = blue) [ fd 10 ] ;; all non-blue turtles move forward 10 steps
For each patch, reports the sum of the values of patch-variable in the 8 surrounding patches (nsum) or 4 surrounding patches (nsum4).
Note that nsum/nsum4 are equivalent to the combination of the sum, values-from, and neighbors/neighbors4 primitives:
sum values-from neighbors [var] ;; does the same thing as "nsum var" sum values-from neighbors4 [var] ;; does the same thing as "nsum4 var"
Therefore nsum and nsum4 are included as separate primitives mainly for backwards compatibility with older versions of NetLogo, which did not have the neighbors and neighbors4 primitives.
See also neighbors, neighbors4.
Reports the value of the VARIABLE of the given agent. Can also be used to set the value of the variable.
show pxcor-of one-of patches ;; prints the value of a random patch's pxcor variable set color-of one-of turtles red ;; a randomly chosen turtle turns red ask turtles [ set pcolor-of (patch-at -1 0) red ] ;; each turtle turns the patch on its left red
From an agentset, reports a random agent. If the agentset is empty, reports nobody.
From a list, reports a random list item. It is an error for the list to be empty.
ask one-of patches [ set pcolor green ] ;; a random patch turns green set pcolor-of one-of patches green ;; another way to say the same thing ask patches with [any? turtles-here] [ show one-of turtles-here ] ;; for each patch containing turtles, prints one of ;; those turtles ;; suppose mylist is [1 2 3 4 5 6] show one-of mylist ;; prints a value randomly chosen from the list
See also n-of.
Reports true if either boolean1 or boolean2, or both, is true.
Note that if condition1 is true, then condition2 will not be run (since it can't affect the result).
if (pxcor > 0) or (pycor > 0) [ set pcolor red ] ;; patches turn red except in lower-left quadrant
Reports an agentset consisting of all turtles on the calling turtle's patch (not including the caller itself). If a breed is specified, only turtles with the given breed are included.
;; suppose I am one of 10 turtles on the same patch show count other-turtles-here => 9
Example using breeds:
breed [cats cat] breed [dogs dog] show count other-dogs-here ;; prints the number of dogs (that are not me) on my patch
See also turtles-here.
Given a link and one of it's ends, this reports the other end of that link. First we "Ask" one of the ends and then "ask" the link. In the inner block "other-end" can be used as an idiom for the other-end of the link besides the end "ask"-ed earlier. The syntax is as shown below.
Suppose a link L connects nodes N1 and N2.
ask N1
[
ask L
[
show __other-end ;; prints N2
]
]
ask N2
[
ask L
[
show __other-end ;; prints N1
]
]
This reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Reports true if there is a link going from the caller to agent.
to check-friendship-neighbors
ca
cct-turtles 2[]
ask turtle 0
[
__create-link-to turtle 1[]
show __in-link-neighbor? turtle 1 ;; prints false
show __out-link-neighbor? turtle 1 ;; prints true
]
ask turtle 1
[
show __in-link-neighbor? turtle 0 ;; prints true
show __out-link-neighbor? turtle 0 ;; prints false
]
end
This reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Reports the agentset of all the node turtles that have links coming from the caller to them.
breed [links link] ;; breed for network links to become-friendly ;; node procedure __create-links-to friends [] show __out-link-neighbors ;; prints the agentset of friends end
This reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Reports the link turtle from the call to the agent. If no link exists then it reports nobody.
to find-friendship-with
ca
cct 2 []
ask turtle 0
[
__create-link-to turtle 1 []
__create-link-from turtle 1 []
show __in-link-from turtle 1 ;; prints turtle 3
show __out-link-to turtle 1 ;; prints turtle 2
show __link-with turtle 1 ;; prints turtle 2
]
end
This reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
These commands are the same as the print, show, type, and write commands except that value is printed in the model's output area, instead of in the Command Center. (If the model does not have a separate output area, then the Command Center is used.)
Given two integers, reports the single patch with the given pxcor and pycor. (The coordinates are the actual coordinates; they are not computed relative to the calling agent, as with patch-at.) pxcor and pycor must be integers.
ask (patch 3 -4) [ set pcolor green ] ;; patch with pxcor of 3 and pycor of -4 turns green
See also patch-at.
Reports the single patch that is the given distance "ahead" of the calling turtle, that is, along the turtle's current heading. Reports nobody if the patch does not exist because it is outside the world.
set pcolor-of (patch-ahead 1) green ;; turns the patch 1 in front of the calling turtle ;; green; note that this might be the same patch ;; the turtle is standing on
See also patch-at, patch-left-and-ahead, patch-right-and-ahead, patch-at-heading-and-distance.
Reports the single patch at (dx, dy) from the caller, that is, dx patches east and dy patches north of the caller. (If the caller is the observer, the given offsets are computed from the origin.) Reports nobody if the patch does not exist because it is outside the world.
ask patch-at 1 -1 [ set pcolor green ] ;; if caller is the observer, turn the patch ;; at (1, -1) green ;; if caller is a turtle or patch, turns the ;; patch just southeast of the caller green
See also patch, patch-ahead, patch-left-and-ahead, patch-right-and-ahead, patch-at-heading-and-distance.
patch-at-heading-and-distance reports the single patch that is the given distance from the calling turtle or patch, along the given absolute heading. (In contrast to patch-left-and-ahead and patch-right-and-ahead, the calling turtle's current heading is not taken into account.) Reports nobody if the patch does not exist because it is outside the world.
set pcolor-of (patch-at-heading-and-distance -90 1) green ;; turns the patch 1 to the west of the calling patch ;; green
See also patch, patch-at, patch-left-and-ahead, patch-right-and-ahead.
patch-here reports the patch under the turtle.
Note that this reporter isn't available to a patch because a patch can just say "self".
Reports the single patch that is the given distance from the calling turtle, in the direction turned left or right the given angle (in degrees) from the turtle's current heading. Reports nobody if the patch does not exist because it is outside the world.
(If you want to find a patch in a given absolute heading, rather than one relative to the current turtle's heading, use patch-at-heading-and-distance instead.)
set pcolor-of (patch-right-and-ahead 30 1) green ;; the calling turtle "looks" 30 degrees right of its ;; current heading at the patch 1 unit away, and turns ;; that patch green; note that this might be the same ;; patch the turtle is standing on
See also patch, patch-at, patch-at-heading-and-distance.
Reports the agentset consisting of all patches.
Reports a patch agentset made by gathering together all the patches reported by reporter for each agent in agentset.
For each agent, the reporter must report a patch agentset, a single patch, or nobody.
patches-from turtles [patch-here] ;; reports the set of all patches with turtles on them; ;; if there are many more patches than turtles, this will ;; run much faster than "patches with [any? turtles-here]"
See also turtles-from.
This keyword, like the globals, breed, <breed>-own, and turtles-own keywords, can only be used at the beginning of a program, before any function definitions. It defines the variables that all patches can use.
All patches will then have the given variables and be able to use them.
All patch variables can also be directly accessed by any turtle standing on the patch.
See also globals, turtles-own, breed, <breeds>-own.
This is a built-in patch variable. It holds the color of the patch. You can set this variable to make the patch change color.
All patch variables can be directly accessed by any turtle standing on the patch.
See also color.
The turtle changes modes between drawing lines, removing lines or neither. The lines will always be displayed on top of the patches and below the turtles. To change the color of the pen set the color of the turtle using set color.
Note: When a turtle's pen is down, all movement commands cause lines to be drawn, including jump and setxy.
Note: These commands are equivalent to setting the turtle variable "pen-mode" to "down" , "up", and "erase".
Note: On Windows drawing and erasing a line might not erase every pixel.
This is a built-in turtle variable. It holds the state of the turtle's pen. You set the variable to draw lines, erase lines or stop either of these actions. Possible values are "up", "down", and "erase".
This is a built-in turtle variable. It holds the width of the line, in pixels, that the turtle will draw (or erase) when the pen is down (or erasing).
This is a built-in patch variable. It may hold a value of any type. The patch appears in the view with the given value "attached" to it as text. You can set this variable to add, change, or remove a patch's label.
All patch variables can be directly accessed by any turtle standing on the patch.
See also plabel-color, label, label-color.
This is a built-in patch variable. It holds a number greater than or equal to 0 and less than 140. This number determines what color the patch's label appears in (if it has a label). You can set this variable to change the color of a patch's label.
All patch variables can be directly accessed by any turtle standing on the patch.
See also plabel, label, label-color.
Increments the x-value of the plot pen by plot-pen-interval, then plots a point at the updated x-value and a y-value of number. (The first time the command is used on a plot, the point plotted has an x-value of 0.)
Reports the name of the current plot (a string).
Puts down (or up) the current plot-pen, so that it draws (or doesn't). (By default, all pens are down initially.)
Clears everything the current plot pen has drawn, moves it to (0,0), and puts it down. If the pen is a permanent pen, the color and mode are reset to the default values from the plot Edit dialog.
Moves the current plot pen to the point with coordinates (number1, number2). If the pen is down, a line, bar, or point will be drawn (depending on the pen's mode).
Reports the minimum or maximum value on the x or y axis of the current plot.
These values can be set with the commands set-plot-x-range and set-plot-y-range. (Their default values are set from the plot Edit dialog.)
On a list, reports the first position of item in list, or false if it does not appear.
On strings, reports the position of the first appearance string1 as a substring of string2, or false if it does not appear.
Note: The positions are numbered beginning with 0, not with 1.
;; suppose mylist is [2 7 4 7 "Bob"] show position 7 mylist => 1 show position 10 mylist => false show position "rin" "string" => 2
See also member?.
Reports number rounded to places decimal places.
If places is negative, the rounding takes place to the left of the decimal point.
show precision 1.23456789 3 => 1.235 show precision 3834 -3 => 4000
Prints value in the Command Center, followed by a carriage return.
The calling agent is not printed before the value, unlike show.
See also show, type, and write.
See also output-print.
These are built-in patch variables. They hold the x and y coordinate of the patch. They are always integers. You cannot set these variables, because patches don't move.
pxcor is greater than or equal to min-pxcor and less than or equal to max-pxcor; similarly for pycor and min-pycor and max-pycor.
All patch variables can be directly accessed by any turtle standing on the patch.
If number is positive, reports a random integer greater than or equal to 0, but strictly less than number.
If number is negative, reports a random integer less than or equal to 0, but strictly greater than number.
If number is zero, the result is always 0 as well.
Note: In versions of NetLogo prior to version 2.0, this primitive reported a floating point number if given a floating point input. This is no longer the case. If you want a floating point answer, you must now use random-float instead.
show random 3 ;; prints 0, 1, or 2 show random -3 ;; prints 0, -1, or -2 show random 3.0 ;; prints 0, 1, or 2 show random 3.5 ;; prints 0, 1, 2, or 3
See also random-float.
If number is positive, reports a random floating point number greater than or equal to 0.0 but strictly less than number.
If number is negative, reports a random floating point number less than or equal to 0.0, but strictly greater than number.
If number is zero, the result is always 0.0.
show random-float 3 ;; prints a number at least 0.0 but less than 3.0, ;; for example 2.589444906014774 show random-float 2.5 ;; prints a number at least 0.0 but less than 2.5, ;; for example 1.0897423196760796
Reports an accordingly distributed random number with the mean and, in the case of the normal distribution, the standard-deviation.
random-exponential reports an exponentially distributed random floating point number.
random-gamma reports a gamma-distributed random floating point number as controlled by the floating point alpha and lambda parameters. Both inputs must be greater than zero. (Note: for results with a given mean and variance, use inputs as follows: alpha = mean * mean / variance; lambda = 1 / (variance / mean).)
random-normal reports a normally distributed random floating point number.
random-poisson reports a Poisson-distributed random integer.
show random-exponential 2 ;; prints an exponentially distributed random floating ;; point number with a mean of 2 show random-normal 10.1 5.2 ;; prints a normally distributed random floating point ;; number with a mean of 10.1 and a standard deviation ;; of 5.2 show random-poisson 3.4 ;; prints a Poisson-distributed random integer with a ;; mean of 3.4
NOTE: This primitive should not be used in new models. It is included only for backwards compatibility with NetLogo 1.x. It will not necessarily continue to be supported in future versions of NetLogo.
When a NetLogo 1.x model is read into NetLogo 2.0 or higher, all uses of the "random" primitive are automatically converted to "random-int-or-float" instead, because the meaning of "random" has changed. It used to sometimes return an integer and sometimes a floating point number; now it always reports an integer. This primitive mimics the old behavior, as follows:
If number is positive, reports a random number greater than or equal to 0 but strictly less than number.
If number is negative, the number reported is less than or equal to 0, but strictly greater than number.
If number is zero, the result is always zero as well.
If number is an integer, reports a random integer.
If number is floating point (has a decimal point), reports a floating point number.
show random-int-or-float 3 ;; prints 0, 1, or 2 show random-int-or-float 5.0 ;; prints a number at least 0.0 but less than 5.0, ;; for example 4.686596634174661
Reports a random integer ranging from min-pxcor (or -y) to max-pxcor (or -y) inclusive.
ask turtles [ ;; move each turtle to the center of a random patch setxy random-pxcor random-pycor ]
See also random-xcor, random-ycor.
Sets the seed of the pseudo-random number generator to the integer part of number. The seed may be any integer in the range supported by NetLogo (-2147483648 to 2147483647).
See the Random Numbers section of the Programming Guide for more details.
random-seed 47823 show random 100 => 57 show random 100 => 91 random-seed 47823 show random 100 => 57 show random 100 => 91
Reports a random floating point number from the allowable range of turtle coordinates along the given axis, x or y.
Turtle coordinates range from min-pxcor - 0.5 (inclusive) to max-pxcor + 0.5 (exclusive) horizontally; vertically, substitute -y for -x.
ask turtles [ ;; move each turtle to a random point setxy random-xcor random-ycor ]
See also random-pxcor, random-pycor.
Interprets the given string as if it had been typed in the Command Center, and reports the resulting value. The result may be a number, list, string, or boolean value, or the special value "nobody".
Useful in conjunction with the user-input primitive for converting the user's input into usable form.
show read-from-string "3" + read-from-string "5" => 8 show length read-from-string "[1 2 3]" => 3 crt read-from-string user-input "Make how many turtles?" ;; the number of turtles input by the user ;; are created
Reduces a list from left to right using reporter, resulting in a single value. This means, for example, that reduce [?1 + ?2] [1 2 3 4] is equivalent to (((1 + 2) + 3) + 4). If list has a single item, that item is reported. It is an error to reduce an empty list.
In reporter, use ?1 and ?2 to refer to the two objects being combined.
Since it can be difficult to develop an intuition about what reduce does, here are some simple examples which, while not useful in themselves, may give you a better understanding of this primitive:
show reduce [?1 + ?2] [1 2 3] => 6 show reduce [?1 - ?2] [1 2 3] => -4 show reduce [?2 - ?1] [1 2 3] => 2 show reduce [?1] [1 2 3] => 1 show reduce [?2] [1 2 3] => 3 show reduce [sentence ?1 ?2] [[1 2] [3 [4]] 5] => [1 2 3 [4] 5] show reduce [fput ?2 ?1] (fput [] [1 2 3 4 5]) => [5 4 3 2 1]
Here are some more useful examples:
;; find the longest string in a list
to-report longest-string [strings]
report reduce
[ifelse-value (length ?1 >= length ?2) [?1] [?2]]
strings
end
show longest-string ["hi" "there" "!"]
=> "there"
;; count the number of occurrences of an item in a list
to-report occurrences [x xs]
report reduce
[ifelse-value (?2 = x) [?1 + 1] [?1]] (fput 0 xs)
end
show occurrences 1 [1 2 1 3 1 2 3 1 1 4 5 1]
=> 6
;; evaluate the polynomial, with given coefficients, at x
to-report eval-polynomial [coeffs x]
report reduce [(x * ?1) + ?2] coeffs
end
;; evaluate 3x^2 + 2x + 1 at x = 4
show eval-polynomial [3 2 1] 4
=> 57
Reports the remainder when number1 is divided by number2. This is equivalent to the following NetLogo code:
number1 - (int (number1 / number2)) * number2
show remainder 62 5 => 2 show remainder -8 3 => -2
See also mod. mod and remainder behave the same for positive numbers, but differently for negative numbers.
For a list, reports a copy of list with all instances of item removed.
For strings, reports a copy of string2 with all the appearances of string1 as a substring removed.
set mylist [2 7 4 7 "Bob"] set mylist remove 7 mylist ;; mylist is now [2 4 "Bob"] show remove "na" "banana" => "ba"
Reports a copy of list with all duplicate items removed. The first of each item remains in place.
set mylist [2 7 4 7 "Bob" 7] set mylist remove-duplicates mylist ;; mylist is now [2 7 4 "Bob"]
For a list, reports a copy of list with the item at the given index removed.
For strings, reports a copy of string2 with the character at the given index removed.
Note that the indices begin from 0, not 1. (The first item is item 0, the second item is item 1, and so on.)
set mylist [2 7 4 7 "Bob"] set mylist remove-item 2 mylist ;; mylist is now [2 7 7 "Bob"] show remove-item 3 "banana" => "banna"
Used for removing link turtles between node turtles.
__remove-<breed>-to removes the link turtle from the caller to agent. __remove-<breed>-to removes all agents in agentset. __remove-<breed>-from removes the link turtle from agent or all agents in agentset to the caller.
__remove-<breed>-with ignores direction and removes link turtles going in either direction.
__remove-<breed>-to and __remove-<breed>-from throw an error if the caller is not linked to agent or one or more agents in agentset in the direction that they try to remove in. __remove-<breed>-with throws an error only if there are no links of links breed in either direction.
breed [links link] ;; breed for network links to reduce-friends ;; node procedure __remove-link-to one-of __link-neighbors end to become-nasty ;; node procedure __remove-links-to __link-neighbors ;; breaks any friendships this node had end
This command is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Runs commands number times.
pd repeat 36 [ fd 1 rt 10 ] ;; the turtle draws a circle
On a list, replaces an item in that list. index is the index of the item to be replaced, starting with 0. (The 6th item in a list would have an index of 5.) Note that "replace-item" is used in conjunction with "set" to change a list.
Likewise for a string, but the given character of string1 removed and the contents of string2 spliced in instead.
show replace-item 2 [2 7 4 5] 15 => [2 7 15 5] show replace-item 1 "sat" "lo" => "slot"
Immediately exits from the current to-report procedure and reports value as the result of that procedure. report and to-report are always used in conjunction with each other. See to-report for a discussion of how to use them.
The observer stops watching, following, or riding any turtles (or patches). (If it wasn't watching, following, or riding anybody, nothing happens.) In the 3D view, the observer also returns to its default position (above the origin, looking straight down).
Resets the global clock to zero. See also timer.
Reports a reversed copy of the given list or string.
show mylist ;; mylist is [2 7 4 "Bob"] set mylist reverse mylist ;; mylist now is ["Bob" 4 7 2] show reverse "string" => "gnirts"
Reports a number in the range 0 to 140, not including 140 itself, that represents the given color, specified in the RGB spectrum, in NetLogo's color space.
All three inputs should be in the range 0.0 to 1.0.
The color reported may be only an approximation, since the NetLogo color space does not include all possible colors. (See hsb for a description of what parts of the HSB color space NetLogo colors cover; this is difficult to characterize in RGB terms.)
show rgb 0 0 0 => 0.0 ;; black show rgb 0 1.0 1.0 => 85.0 ;; cyan
See also extract-rgb, hsb, and extract-hsb.
Set the perspective to turtle.
Every time turtle moves the observer also moves. Thus, in the 2D View the turtle will stay at the center of the view. In the 3D view it is as if looking through the eyes of the turtle. If the turtle dies, the view will return to the default position.
See also reset-perspective, watch, follow, subject.
Asks the observer to ride the calling turtle.
See also ride.
The turtle turns right by number degrees. (If number is negative, it turns left.)
Reports the integer nearest to number.
If the decimal portion of number is exactly .5, the number is rounded in the positive direction.
Note that rounding in the positive direction is not always how rounding is done in other software programs. (In particular, it does not match the behavior of StarLogoT, which always rounded numbers ending in 0.5 to the nearest even integer.) The rationale for this behavior is that it matches how turtle coordinates relate to patch coordinates in NetLogo. For example, if a turtle's xcor is -4.5, then it is on the boundary between a patch whose pxcor is -4 and a patch whose pxcor is -5, but the turtle must be considered to be in one patch or the other, so the turtle is considered to be in the patch whose pxcor is -4, because we round towards the positive numbers.
show round 4.2 => 4 show round 4.5 => 5 show round -4.5 => -4
This agent interprets the given string as a sequence of one or more NetLogo commands and runs them.
The code runs in the agent's current context, which means it has access to the values of local variables, "myself", and so on.
See also runresult.
This agent interprets the given string as a NetLogo reporter and runs it, reporting the result obtained.
The code runs in the agent's current context, which means it has access to the values of local variables, "myself", and so on.
See also run.
Reports a shade of color proportional to number.
If range1 is less than range2, then the larger the number, the lighter the shade of color. But if range2 is less than range1, the color scaling is inverted.
If number is less than range1, then the darkest shade of color is chosen.
If number is greater than range2, then the lightest shade of color is chosen.
Note: for color shade is irrelevant, e.g. green and green + 2 are equivalent, and the same spectrum of colors will be used.
ask turtles [ set color scale-color red age 0 50 ] ;; colors each turtle a shade of red proportional ;; to its value for the age variable
Reports this turtle or patch.
"self" and "myself" are very different. "self" is simple; it means "me". "myself" means "the turtle or patch who asked me to do what I'm doing right now."
ask turtles with [self != myself] [ die ] ;; this turtle kills all other turtles
See also myself.
After a semicolon, the rest of the line is ignored. This is useful for adding "comments" to your code -- text that explains the code to human readers. Extra semicolons can be added for visual effect.
NetLogo's Edit menu has items that let you comment or uncomment whole sections of code.
Makes a list out of the values. If any value is a list, its items are included in the result directly, rather than being included as a sublist. Examples make this clearer:
show sentence 1 2 => [1 2] show sentence [1 2] 3 => [1 2 3] show sentence 1 [2 3] => [1 2 3] show sentence [1 2] [3 4] => [1 2 3 4] show sentence [[1 2]] [[3 4]] => [[1 2] [3 4]] show (sentence [1 2] 3 [4 5] (3 + 3) 7) => [1 2 3 4 5 6 7]
Sets variable to the given value.
Variable can be any of the following:
Sets the current directory that is used by the primitives file-delete, file-exists?, and file-open.
The current directory is not used if the above commands are given an absolute file path. This is defaulted to the user's home directory for new models, and is changed to the model's directory when a model is opened.
Note that in Windows file paths the backslash needs to be escaped within a string by using another backslash "C:\\"
The change is temporary and is not saved with the model.
Note: in applets, this command has no effect, since applets are only allowed to read files from the same directory on the server where the model is stored.
set-current-directory "C:\\NetLogo" ;; Assume it is a Windows Machine file-open "myfile.txt" ;; Opens file "C:\\NetLogo\\myfile.txt"
Sets the current plot to the plot with the given name (a string). Subsequent plotting commands will affect the current plot.
The current plot's current pen is set to the pen named penname (a string). If no such pen exists in the current plot, a runtime error occurs.
Specifies a default initial shape for all turtles, or for a particular breed. When a turtle is created, or it changes breeds, it shape is set to the given shape.
This command doesn't affect existing turtles, only turtles you create afterwards.
The specified breed must be either turtles or a breed defined by the breed keyword, and the specified string must be the name of a currently defined shape.
In new models, the default shape for all turtles is "default".
Note that specifying a default shape does not prevent you from changing an individual turtle's shape later; turtles don't have to be stuck with their breed's default shape.
create-turtles 1 ;; new turtle's shape is "default" create-cats 1 ;; new turtle's shape is "default" set-default-shape turtles "circle" create-turtles 1 ;; new turtle's shape is "circle" create-cats 1 ;; new turtle's shape is "circle" set-default-shape cats "cat" set-default-shape dogs "dog" create-cats 1 ;; new turtle's shape is "cat" ask cats [ set breed dogs ] ;; all cats become dogs, and automatically ;; change their shape to "dog"
See also shape.
Set the current plot pen's plot interval so that, given the current x range for the plot, there would be integer number of bars drawn if the histogram-from or histogram-list commands were called.
See also histogram-from.
Specifies the thickness of lines and outlined elements in the turtle's shape.
The default value is 0. This always produces lines one pixel thick.
Non-zero values are interpreted as thickness in patches. A thickness of 1, for example, produces lines which appear one patch thick. (It's common to use a smaller value such as 0.5 or 0.2.)
Lines are always at least one pixel thick.
This reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details. (Note that the command can be used with non-link turtles too, though.)
Sets the color of the current plot pen to number.
Tells the current plot pen to move a distance of number in the x direction during each use of the plot command. (The plot pen interval also affects the behavior of the histogram-from and histogram-list commands.)
Sets the mode the current plot pen draws in to number. The allowed plot pen modes are:
The default mode for new pens is 0 (line mode).
Sets the minimum and maximum values of the x or y axis of the current plot.
The change is temporary and is not saved with the model. When the plot is cleared, the ranges will revert to their default values as set in the plot's Edit dialog.
The turtle sets its x-coordinate to x and its y-coordinate to y.
Equivalent to set xcor x set ycor y, except it happens in one time step instead of two.
If x or y is outside the world, NetLogo will throw a runtime error.
setxy 0 0 ;; turtle moves to the middle of the center patch setxy random-xcor random-ycor ;; turtle moves to a random point setxy random-pxcor random-pycor ;; turtle moves to the center of a random patch
Reports true if both colors are shades of one another, false otherwise.
show shade-of? blue red => false show shade-of? blue (blue + 1) => true show shade-of? gray white => true
This is a built-in turtle variable. It holds a string that is the name of the turtle's current shape. You can set this variable to change a turtle's shape. New turtles have the shape "default" unless the a different shape has been specified using set-default-shape.
Example:
ask turtles [ set shape "wolf" ] ;; assumes you have made a "wolf" ;; shape in NetLogo's Shapes Editor
See also set-default-shape, shapes.
Reports a list of strings containing all of the turtle shapes in the model.
New shapes can be created, or imported from the shapes library or from other models, in the Shapes Editor.
show shapes => ["default" "airplane" "arrow" "box" "bug" ... ask turtles [ set shape one-of shapes ]
Prints value in the Command Center, preceded by the calling agent, and followed by a carriage return. (The calling agent is included to help you keep track of what agents are producing which lines of output.) Also, all strings have their quotes included similar to write.
See also print, type, and write.
See also output-show.
The turtle becomes visible again.
Note: This command is equivalent to setting the turtle variable "hidden?" to false.
See also hide-turtle.
Reports a new list containing the same items as the input list, but in randomized order.
show shuffle [1 2 3 4 5] => [5 2 4 1 3] show shuffle [1 2 3 4 5] => [1 3 5 2 4]
Reports the sine of the given angle. Assumes angle is given in degrees.
show sin 270 => -1.0
This is a built-in turtle variable. It holds a number that is the turtle's apparent size. The default size is 1.0, which means that the turtle is the same size as a patch. You can set this variable to change a turtle's size.
If the input is a list, reports a list containing the same items as the input list, but in ascending order. If there is at least one number in the list, the list is sorted in numerically ascending order and any non-numeric items of the input list are discarded. If there are no numbers, but at least one string in the list, the list is sorted in alphabetically ascending order and any non-string items are discarded.
If the input is an agentset or a list of agents, reports a list (never an agentset) of agents. If the agents are turtles, they are listed in ascending order by who number. If the agents are patches, they are listed left-to-right, top-to-bottom.
show sort [3 1 4 2]
=> [1 2 3 4]
let n 0
foreach sort patches [
ask ? [
set plabel n
set n n + 1
]
]
;; patches are labeled with numbers in left-to-right,
;; top-to-bottom order
If the input is a list, reports a new list containing the same items as the input list, in a sorted order defined by the boolean (true or false) reporter.
In reporter, use ?1 and ?2 to refer to the two objects being compared. reporter should be true if ?1 comes strictly before ?2 in the desired sort order, and false otherwise.
If the input is an agentset or a list of agents, reports a list (never an agentset) of agents.
show sort-by [?1 < ?2] [3 1 4 2] => [1 2 3 4] show sort-by [?1 > ?2] [3 1 4 2] => [4 3 2 1] show sort-by [length ?1 < length ?2] ["zzz" "z" "zz"] => ["z" "zz" "zzz"] foreach sort-by [size-of ?1 < size-of ?2] turtles [ ask ? [ do-something ] ] ;; turtles run "do-something" one at a time, in ;; ascending order by size
Creates number new turtles on the current patch. The new turtles have random colors and orientations, and they immediately run commands. This is useful for giving the new turtles different colors, headings, or whatever. (The new turtles are created all at once then run one at a time, in random order.)
If the sprout-<breeds> form is used, the new turtles are created as members of the given breed.
sprout 1 [ set color red ] sprout-sheep 1 [ set color black ]
Note: While the commands are running, no other agents are allowed to run any code (as with the without-interruption command). This ensures that the new turtles cannot interact with any other agents until they are fully initialized. In addition, no display updates take place until the commands are done. This ensures that the new turtles are never drawn in the view until they are fully initialized.
Reports the square root of number.
The calling turtle leaves an image of its shape in the drawing at its current location.
Note: The shapes made by stamp may not be pixel-for-pixel identical from computer to computer.
The calling turtle removes any pixels below it in the drawing inside the bounds of its shape.
Note: The shapes made by stamp-erase may not be pixel-for-pixel identical from computer to computer.
Reports the unbiased statistical standard deviation of a list of numbers. Ignores other types of items.
show standard-deviation [1 2 3 4 5 6] => 1.8708286933869707 show standard-deviation values-from turtles [energy] ;; prints the standard deviation of the variable "energy" ;; from all the turtles
User-defined procedure which, if it exists, will be called when a model is first loaded.
to startup setup end
The calling agent exits immediately from the enclosing procedure, ask, or ask-like construct (cct, hatch, sprout). Only the current procedure stops, not all execution for the agent.
Note: stop can be used to stop a forever button. If the forever button directly calls a procedure, then when that procedure stops, the button stops. (In a turtle or patch forever button, the button won't stop until every turtle or patch stops -- a single turtle or patch doesn't have the power to stop the whole button.)
Reports the turtle (or patch) that the observer is currently watching, following, or riding. Reports nobody if there is no such turtle (or patch).
Reports just a section of the given list or string, ranging between the first position (inclusive) and the second position (exclusive).
Note: The positions are numbered beginning with 0, not with 1.
show sublist [99 88 77 66] 1 3 => [88 77] show substring "turtle" 1 4 => "urt"
Computes the difference between the given headings, that is, the number of degrees in the smallest angle by which heading2 could be rotated to produce heading1. A positive answer means a clockwise rotation, a negative answer counterclockwise. The result is always in the range -180 to 180, but is never exactly -180.
Note that simply subtracting the two headings using the - (minus) operator wouldn't work. Just subtracting corresponds to always rotating clockwise from heading2 to heading1; but sometimes the counterclockwise rotation is shorter. For example, the difference between 5 degrees and 355 degrees is 10 degrees, not -350 degrees.
show subtract-headings 80 60 => 20 show subtract-headings 60 80 => -20 show subtract-headings 5 355 => 10 show subtract-headings 355 5 => -10 show subtract-headings 180 0 => 180 show subtract-headings 0 180 => 180
Reports the sum of the items in the list.
show sum values-from turtles [energy] ;; prints the total of the variable "energy" ;; from all the turtles
Reports the tangent of the given angle. Assumes the angle is given in degrees.
Connects leaf-turtle to root-turtle so that the movement of the root-turtle affects the location and heading of the leaf-turtle
When the root turtle moves, the leaf turtles moves the same distance, in the same direction. The heading of the leaf turtle is not affected. This works with forward, jump, and setting the xcor or ycor of the root turtle.
When the root turtle turns right or left, the leaf turtle is rotated around the root turtle the same amount. The heading of the leaf turtle is also changed by the same amount.
See also __untie
This command is part of the experimental Tie support in NetLogo. See the Tie section of the Programming Guide for more details.
Reports how many seconds have passed since the command reset-timer was last run (or since NetLogo started). The potential resolution of the clock is milliseconds. (Whether you get resolution that high in practice may vary from system to system, depending on the capabilities of the underlying Java Virtual Machine.)
Used to begin a command procedure.
to setup ca crt 500 end to circle [radius] cct 100 [ fd radius ] end
Used to begin a reporter procedure.
The body of the procedure should use report to report a value for the procedure. See report.
to-report average [a b]
report (a + b) / 2
end
to-report absolute-value [number]
ifelse number >= 0
[ report number ]
[ report (- number) ]
end
to-report first-turtle?
report who = 0 ;; reports true or false
end
Reports the heading from this agent to the given agent.
If wrapping is allowed by the topology and the wrapped distance (around the edges of the view) is shorter than the on-screen distance, towards will report the heading of the wrapped path.
Note: asking for the heading from an agent to itself, or an agent on the same location, will cause a runtime error.
Reports the heading from the turtle or patch towards the point (x,y).
If wrapping is allowed by the topology and the wrapped distance (around the edges of the view) is shorter than the on-screen distance, towardsxy will report the heading of the wrapped path.
Note: asking for the heading to the point the agent is already standing on will cause a runtime error.
Reports the turtle with the given ID number, or nobody if there is no such turtle. number must be an integer.
set color-of turtle 5 red ;; turtle with id number 5 turns red ask turtle 5 [ set color red ] ;; another way to do the same thing
Reports the agentset consisting of all turtles.
show count turtles ;; prints the number of turtles
Reports an agentset containing the turtles on the patch (dx, dy) from the caller (including the caller itself if it's a turtle). If the caller is the observer, dx and dy are calculated from the origin (0,0).
;; suppose I have 40 turtles at the origin show count turtles-at 0 0 => 40
If the name of a breed is substituted for "turtles", then only turtles of that breed are included.
breed [cats cat] breed [dogs dog] create-custom-dogs 5 [ setxy 2 3 ] show count dogs-at 2 3 => 5
Reports a turtle agentset made by gathering together all the turtles reported by reporter for each agent in agentset.
For each agent, the reporter must report a turtle agentset, a single turtle, or nobody.
turtles-from patches [one-of turtles-here] ;; reports a turtle set containing one turtle from ;; each patch (that has any turtles on it) turtles-from neighbors [turtles-here] ;; if run by a turtle or patch, reports the set of ;; all turtles on the neighboring eight patches; note that ;; this could be written more concisely using turtles-on, ;; like this: ;; turtles-on neighbors
See also patches-from, turtles-on.
Reports an agentset containing all the turtles on the caller's patch (including the caller itself if it's a turtle).
ca crt 10 ask turtle 0 [ show count turtles-here ] => 10
If the name of a breed is substituted for "turtles", then only turtles of that breed are included.
breed [cats cat] breed [dogs dog] create-cats 5 create-dogs 1 ask dogs [ show count cats-here ] => 5
See also other-turtles-here.
Reports an agentset containing all the turtles that are on the given patch or patches, or standing on the same patch as the given turtle or turtles.
ask turtles [
if not any? turtles-on patch-ahead 1
[ fd 1 ]
]
ask turtles [
if not any? turtles-on neighbors [
die-of-loneliness
]
]
If the name of a breed is substituted for "turtles", then only turtles of that breed are included.
See also turtles-from.
The turtles-own keyword, like the globals, breed, <breeds>-own, and patches-own keywords, can only be used at the beginning of a program, before any function definitions. It defines the variables belonging to each turtle.
If you specify a breed instead of "turtles", only turtles of that breed have the listed variables. (More than one breed may list the same variable.)
breed [cats cat ] breed [dogs dog] breed [hamsters hamster] turtles-own [eyes legs] ;; applies to all breeds cats-own [fur kittens] hamsters-own [fur cage] dogs-own [hair puppies]
See also globals, patches-own, breed, <breeds>-own.
Prints value in the Command Center, not followed by a carriage return (unlike print and show). The lack of a carriage return allows you to print several values on the same line.
The calling agent is not printed before the value. unlike show.
type 3 type " " print 4 => 3 4
See also print, show, and write.
See also output-type.
Disconnects leaf-turtle from root-turtle if they were previously tied together.
See also __tie
This command is part of the experimental Tie support in NetLogo. See the Tie section of the Programming Guide for more details.
Reports the turtle heading (between 0 and 359 degrees) in the direction of the maximum value of the variable patch-variable, of the patches in a one-patch radius of the turtle. (This could be as many as eight or as few as five patches, depending on the position of the turtle within its patch.)
If there are multiple patches that have the same greatest value, a random one of those patches will be selected.
If the patch is located directly to the north, south, east, or west of the patch that the turtle is currently on, a multiple of 90 degrees is reported. However, if the patch is located to the northeast, northwest, southeast, or southwest of the patch that the turtle is currently on, the direction the turtle would need to reach the nearest corner of that patch is reported.
See also uphill4, downhill, downhill4.
Reports the turtle heading (between 0 and 359 degrees) as a multiple of 90 degrees in the direction of the maximum value of the variable patch-variable, of the four patches to the north, south, east, and west of the turtle. If there are multiple patches that have the same greatest value, a random patch from those patches will be selected.
See also uphill, downhill, downhill4.
Opens a dialog that allows the user to choose an existing directory on the system.
It reports a string with the absolute path or false if the user cancels.
set-current-directory user-directory ;; Assumes the user will choose a directory
Opens a dialog that allows the user to choose an existing file on the system.
It reports a string with the absolute file path or false if the user cancels.
file-open user-file ;; Assumes the user will choose a file
Opens a dialog that allows the user to choose a location and name of a new file to be created.
It reports a string with the absolute file path or false if the user cancels.
file-open user-new-file ;; Assumes the user will choose a file
Note that this reporter doesn't actually create the file; normally you would create the file using file-open, as in the example.
Reports the string that a user types into an entry field in a dialog with title value.
value may be of any type, but is typically a string.
show user-input "What is your name?"
Opens a dialog with value displayed as the message.
value may be of any type, but is typically a string.
user-message "There are " + count turtles + " turtles."
Opens a dialog with value displayed as the message and list-of-choices displayed as a popup menu for the user to select from.
Reports the item in list-of-choices selected by the user.
value may be of any type, but is typically a string.
if "yes" = user-one-of? "Set up the model?" [ "yes" "no" ] [ setup ]
Reports true or false based on the user's response to value.
value may be of any type, but is typically a string.
if user-yes-or-no? "Set up the model?" [ setup ]
Reports the value of the reporter for the given agent (turtle or patch).
show value-from (turtle 5) [who * who] => 25 show value-from (patch 0 0) [count turtles in-radius 3] ;; prints the number of turtles located within a ;; three-patch radius of the origin
Reports a list that contains the value of the reporter for each agent in the agentset.
ca crt 4 show values-from turtles [who] => [0 1 2 3] show values-from turtles [who * who] => [0 1 4 9]
Reports the sample variance of a list of numbers. Ignores other types of items.
The sample variance is the sum of the squares of the deviations of the numbers from their mean, divided by one less than the number of numbers in the list.
show variance [2 7 4 3 5] => 3.7
Wait the given number of seconds. (You can use floating-point numbers to specify fractions of seconds.) Note that you can't expect complete precision; the agent will never wait less than the given amount, but might wait slightly more.
repeat 10 [ fd 1 wait 0.5 ]
See also every.
Puts a spotlight on agent. In the 3D view the observer will also turn to face the subject.
See also follow, subject, reset-perspective, watch-me.
Asks the observer to watch the calling agent.
See also watch.
If reporter reports false, exit the loop. Otherwise run commands and repeat.
The reporter may have different values for different agents, so some agents may run commands a different number of times than other agents.
while [any? other-turtles-here] [ fd 1 ] ;; turtle moves until it finds a patch that has ;; no other turtles on it
This is a built-in turtle variable. It holds the turtle's id number (an integer greater than or equal to zero). You cannot set this variable; a turtle's id number never changes.
When NetLogo starts, or after you use the clear-all or clear-turtles commands, new turtles are created with ids in order, starting at 0. If a turtle dies, though, a new turtle may eventually be assigned the same id number that was used by the dead turtle.
Example:
show values-from (turtles with [color = red]) [who]
;; prints a list of the id numbers of all red turtles
;; in the Command Center
ca
cct 100
[ ifelse who < 50
[ set color red ]
[ set color blue ] ]
;; turtles 0 through 49 are red, turtles 50
;; through 99 are blue
You can use the turtle reporter to retrieve a turtle with a given id number. See also turtle.
Takes two inputs: on the left, an agentset (usually "turtles" or "patches"). On the right, a boolean reporter. Reports a new agentset containing only those agents that reported true -- in other words, the agents satisfying the given condition.
show count patches with [pcolor = red] ;; prints the number of red patches
Report the link turtle from the agent to the caller, or from the caller to the agent. If no link exists then it reports nobody.
to find-friendship-with
ca
cct 2 []
ask turtle 0
[
__create-link-to turtle 1 []
__create-link-from turtle 1 []
show __in-link-with turtle 1 ;; prints turtle 3
show __out-link-with turtle 1 ;; prints turtle 2
show __link-with turtle 1 ;; prints turtle 2
]
end
This reporter is part of the experimental Links support in NetLogo. See the Links section of the Programming Guide for more details.
Takes two inputs: on the left, an agentset (usually "turtles" or "patches"). On the right, a reporter. Reports a new agentset containing all agents reporting the maximum value of the given reporter.
show count patches with-max [pxcor] ;; prints the number of patches on the right edge
See also max-one-of
Takes two inputs: on the left, an agentset (usually "turtles" or "patches"). On the right, a reporter. Reports a new agentset containing only those agents that have the minimum value of the given reporter.
show count patches with-min [pycor] ;; prints the number of patches on the bottom edge
See also min-one-of
The agent runs all the commands in the block without allowing other agents to "interrupt". That is, other agents are put "on hold" and do not run any commands until the commands in the block are finished.
crt 5
ask turtles
[ without-interruption
[ type 1 fd 1 type 2 ] ]
=> 1212121212
;; because each turtle will output 1 and move,
;; then output 2. however:
ask turtles
[ type 1 fd 1 type 2 ]
=> 1111122222
;; because each turtle will output 1 and move,
;; then output 2
Concatenates the inputs together and reports the result as a string.
show word "tur" "tle" => "turtle" word "a" 6 => "a6" set directory "c:\\foo\\fish\\" show word directory "bar.txt" => "c:\foo\fish\bar.txt" show word [1 54 8] "fishy" => "[1 54 8]fishy" show (word "a" "b" "c" 1 23) => "abc123"
These reporters give the total width and height of the NetLogo world.
The width and height of the world is the same as max-p(x/y)cor - min-p(x/y)cor + 1.
See also max-pxcor, max-pycor, min-pxcor, and min-pycor
wrap-color checks whether number is in the NetLogo color range of 0 to 140 (not including 140 itself). If it is not, wrap-color "wraps" the numeric input to the 0 to 140 range.
The wrapping is done by repeatedly adding or subtracting 140 from the given number until it is in the 0 to 140 range. (This is the same wrapping that is done automatically if you assign an out-of-range number to the color turtle variable or pcolor patch variable.)
show wrap-color 150 => 10 show wrap-color -10 => 130
This command will output value, which can be a number, string, list, boolean, or nobody to the Command Center not followed by a carriage return (unlike print and show).
The calling agent is not printed before the value, unlike show. Its output will also includes quotes around strings and is prepended with a space.
write "hello world" => "hello world"
See also print, show, and type.
See also output-write.
This is a built-in turtle variable. It holds the current x coordinate of the turtle. This is a floating point number, not an integer. You can set this variable to change the turtle's location.
This variable is always greater than or equal to (min-pxcor - 0.5) and strictly less than (max-pxcor + 0.5).
See also setxy, ycor, pxcor, pycor,
Reports true if either boolean1 or boolean2 is true, but not when both are true.
if (pxcor > 0) xor (pycor > 0) [ set pcolor blue ] ;; upper-left and lower-right quadrants turn blue
This is a built-in turtle variable. It holds the current y coordinate of the turtle. This is a floating point number, not an integer. You can set this variable to change the turtle's location.
This variable is always greater than or equal to (min-pycor - 0.5) and strictly less than (max-pycor + 0.5).
See also setxy, xcor, pxcor, pycor,
These are special local variables. They hold the current inputs to a reporter or command block for certain primitives (for example, the current item of a list being visited by foreach or map).
? is always equivalent to ?1.
You may not set these variables, and you may not use them except with certain primitives, currently foreach, map, reduce, filter, sort-by, and n-values. See those entries for example usage.