Extensions

These sample extensions demonstrate NetLogo's extensions facility, which allows Java programmers to extend NetLogo's capabilities.

For more information on using and writing your own extensions, see the Extensions section of the NetLogo User Manual.

We strongly encourage extension authors to share their extensions with the NetLogo user community. (Even if your extension is not completely finished or documented, it may be still be useful to others.) Please E-mail your extension to us at feedback@ccl.northwestern.edu and we will add it to this web page.

All extensions on this page come with complete Java source code.

for NetLogo 4.0

Bundled extensions

The source code for the Array, Table, GoGo, Profiler, GIS, Sample, and Sound extensions is included with the NetLogo 4.0.4. Look in the extensions directory in your NetLogo installation.

Palette

This extension allows you to create multi-color gradients using rgb color lists. Additionally you can use or browse ColorBrewer color schemes.

Info and download: Palette extension for NetLogo 4.0

Speech

This Mac OS X-only extension provides speech-synthesis capabilities to NetLogo. It is implemented with a Mac OS X text-to-speech class library called A Humble Narrator.

Download: Speech extension for NetLogo 4.0

User Submitted Extensions

These extensions are contributions from the user community and are not included with NetLogo. These extensions are authored by the individual contributor and are not checked by the CCL staff.

Modified Profiler Extension (by Roger Peppe)

This is an updated version of the profiler extension bundled with NetLogo.

I measured it as approximately 10 times faster than the old one. I'm sure there's still room for improvement, though!

I also changed it to replace the inclusive- and exclusive-time primitives with the single reporter, profiler:report-values, which reports a data structure containing all of the profiler information.

Download: Modified Profiler Extension

Modified Array Extension (by Roger Peppe)

This updated version of the array extension bundled with NetLogo contains a few changes made to make certain operations more efficient:

• a primitive for quickly creating an array populated with a single object, rather having to first create a list
• a primitive to allow extension (growing) of the array by setting the element one beyond the end of the array
• a primitive to make it easy and efficient to copy subsections of an array to another array

Download: Modified Array Extension

Strings (by James Steiner)

This provides NetLogo versions of a few standard Java string reporters:

• upper-case ( ... )
• lower-case ( ... )
• trim (removes leading and trailing whitespace)
• starts-with (* true if the first string matches the start of the second string)
• ends-with (* likewise, but matches the end of the second string)
• explode (convert string to a list of characters)
• rex-split (split string to a list, on the given regular expression pattern)
• rex-replace-first (replaces the first match of the pattern in the string with another string)
• rex-replace-all (like replace-first, but replaces all pattern matches)
• rex-match (reports true if the pattern exactly matches the string)
• from-file (** reports the entire file contents as a single string)
• message-digest-5 (reports the md5 hash of the string)
• hash-code (reports the integer hash code of the string)

* this are in-fix operators, i.e. if my-string string:starts-with prefix [ print true ]

** from-file seems to only work well with absolute file paths, as it doesn't seem to hook into the current-directory as expected/hoped.

Download: String extension

Multiple Random Number Generator (by David O'Sullivan)

Usage is:

• rngs: initialise resets everything, deleting all existing random number generators (RNGs) in the extension
• rngs: set-seed initialises a RNG that will be referred to by the supplied id number, with the supplied (positive integer) seed value. A seed value of 0 will be initialised from the system clock
• rngs: random-float returns a random float between 0 and the specified range from the RNG with the supplied id. This can only be called if rngs:set-seed has previously been used to create the specified RNG

Download: Multiple random number generator extension

Priority Queue (by Roger Peppe)

Provides a priority queue type:

• pq:new (reporter) - create and return a new priority queue.
• pq:add q p item (command) - add item with priority p (a number) to the priority queue q.
• pq:remove q (reporter) - remove and return the item with the highest priority from tq. this gives an error if there are no items currently in the queue.
• pq:delete-item q item (command) - delete item from the queue. this operation takes O(n) time, where n is the number of items in the queue.
• pq:peek q (reporter) report the item in the queue with the highest priority, or raise an error if there are no items in the queue.
• pq:peek-priority q (reporter) - report the highest priority in the queue, or raise an error if there are no items in the queue. (actually i think in this version, this it not yet implemented).
• pq:length q (reporter) report the number of items in the queue q.

Download: Priority Queue Extension