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NetLogo network extension

This extension is pre-installed in NetLogo 5.0. (For help with extensions in general, see the NetLogo User Manual.)

This extension is experimental. Although it is presently bundled with NetLogo, it should not be considered a standard, fully-supported part of the application.

The source code for the extension is hosted online at https://github.com/NetLogo/Network-Extension

Usage

Anywhere a link breed is required, links is also accepted.

Path lengths are computed based solely on the number of hops. There isn't currently any way to specify a "weight" or "distance" variable for links.

Ideally, instead of taking a link breed as input, the breed could take the place of link in the primitive name. Currently the extensions API doesn't allow primitives that change name like this, but it should in some future NetLogo version. Anyway, this is why all the names have link in them.

Primitives

network:in-link-radius, network:in-out-link-radius, network:in-in-link-radius

turtle TURTLESET network:in-link-radius RADIUS LINK-BREED
turtle TURTLESET network:in-out-link-radius RADIUS LINK-BREED
turtle TURTLESET network:in-in-link-radius RADIUS LINK-BREED

example: ask one-of bankers [ show other bankers network:in-link-radius 5 friendships ]

Returns the set of turtles within the given distance (number of links followed) of the calling turtle. Searches breadth-first from the calling turtle, following links of the given link breed.

The in-link-radius form works with undirected links. The other two forms work with directed links; out or in specifies whether links are followed in the normal direction (out), or in reverse (in).

network:link-distance

turtle network:link-distance TURTLE LINK-BREED

example: ask one-of-bankers [ show network:link-distance the-best-banker friendships ]

Finds the distance to the destination turtle (number of links followed). Searches breadth-first from the calling turtle, following links of the given link breed.

Reports false if no path exists.

network:link-path, link-path-turtles

turtle network:link-path TURTLE LINK-BREED
turtle network:link-path-turtles TURTLE LINK-BREED

example: ask banker1 [ show network:link-path banker3 friendships ] -> [(link 1 2) (link 2 3)]

example:ask banker1 [ show network:link-path-turtles banker3 friendships ] -> [(banker 1) (banker 2) (banker 3)]

Reports a list of turtles or links following the shortest path from the calling turtle to the destination turtle.

Reports an empty list if no path exists.

If network:link-path-turtles is used, the calling turtle and the destination are included in the list.

Searches breadth-first from the calling turtle, following links of the given link breed.

Follows links at the same depth in random order. If there are multiple shortest paths, a different path may be returned on subsequent calls, depending on the random choices made during search.

network:mean-link-path-length

network:mean-link-path-length TURTLE-SET LINK-BREED

Reports the average shortest-path length between all distinct pairs of nodes in the given set of turtles, following links of the given link breed.

Reports false unless paths exist between all pairs.

Transition guide

Renamed primitives

The primitives in this extension were present in NetLogo 4.1, but with different names. They were renamed as follows:

  • __network-distance to network:link-distance
  • __in-network-radius to network:in-link-radius, network:in-out-link-radius, network:in-in-link-radius
  • __average-path-length to network:mean-link-path-length
  • __network-shortest-path-links to network:link-path
  • __network-shortest-path-nodes to network:link-path-turtles

Omitted primitives

The following primitives, present in NetLogo 4.1 but not NetLogo 5.0, are not included in this extension either:

  • __create-network-preferential
  • __layout-magspring
  • __layout-quick
  • __layout-sphere

For the source code for these primitives, see this commit. But note they are written in the style used by built-in NetLogo primitives. To be brought back to life, they'd need to be changed to use the extensions API instead.

Building

Run the bin/sbt script to build the extension.

If the build succeeds, network.jar is created.

Credits

The first versions of these primitives were written by Forrest Stonedahl.

Terms of Use

CC0

The NetLogo network extension is in the public domain. To the extent possible under law, Uri Wilensky has waived all copyright and related or neighboring rights.