R/igraph 0.4

May 21, 2007

The major new additions in this release is a bunch of community detection algorithms and support for the GML file format. Here is the complete list of changes:

New in the R interface

• as the internal representation changed, graphs stored with ‘save’ with an older igraph version cannot be read back with the new version reliably.

• neighbors returns ordered lists

• topological sorting
• VF2 isomorphism algorithm
• support for reading graphs from the Graph Database for isomorphism
• girth calculation added, thanks to Keith Briggs

• support for reading and writing GML files

• Walktrap community detection algorithm added, thanks to Matthieu Latapy and Pascal Pons
• edge betweenness based community detection algorithm added
• fast greedy algorithm for community detection by Clauset et al. added thanks to Aaron Clauset for sharing his code
• leading eigenvector community detection algorithm by Mark Newman added
• functions for creating denrdograms from the output of the community detection algorithms added
• community.to.membership supporting function added, creates a membership vector from a community structure merge tree

• modularity calculation added

• graphics parameter handling is completely rewritten, uniform handling of colors and fonts, make sure you read ?igraph.plotting
• new plotting parameter for edges: arrow.mode
• a bug corrected when playing a nonlinear barabasi.game
• better looking plotting in 3d using rglplot: edges are 3d too
• rglplot layout is allowed to be two dimensional now
• rglplot suspends updates while drawing, this makes it faster

• loop edges are correctly plotted by all three plotting functions

• better printing of attributes when printing graphs
• summary of a graph prints attribute names
• is.igraph rewritten to make it possible to inherit from the igraph class
• somewhat better looking progress meter for functions which support it

Others

• many functions benefit from the new internal representation and are faster now: transitivity, reciprocity, graph operator functions like intersection and union, etc.
• igraph compiles with Microsoft Visual C++ now
• there were some internal changes to make igraph a real graph algorithm platform in the near future, but these are undocumented now

Bugs corrected

• corrected a bug when reading Pajek files: directed graphs were read as undirected