The igraph library

News

igraph 0.5.1

Released July 14, 2008

See also the release notes at http://cneurocvs.rmki.kfki.hu/igraph/relnotes-0.5.1.html

New in the R interface

• A new layout generator called DrL.
• Uniform sampling of random connected undirected graphs with a given degree sequence.
• Edge labels are plotted at 1/3 of the edge, this is better if the graph has mutual edges.
• Initial and experimental vertex shape support in 'plot'.
• New function, 'graph.adjlist' creates igraph graphs from adjacency lists.
• Conversion to/from graphNEL graphs, from the 'graph' R package.
• Fastgreedy community detection can utilize edge weights now, this was missing from the R interface.
• The 'arrow.width' graphical parameter was added.
• graph.data.frame has a new argument 'vertices'.
• graph.adjacency and get.adjacency support sparse matrices, the 'Matrix' package is required to use this functionality.
• graph.adjacency adds column/row names as 'name' attribute.
• Weighted shortest paths using Dijkstra's or the Belmann-Ford algorithm.
• Shortest path functions return 'Inf' for unreachable vertices.
• New function 'is.mutual' to find mutual edges in a directed graph.
• Added inverse log-weighted similarity measure (a.k.a. Adamic/Adar similarity).
• preference.game and asymmetric.preference.game were rewritten, they are O(|V|+|E|) now, instead of O(|V|^2).
• Edge weight support in function 'get.shortest.paths', it uses Dijkstra's algorithm.

Bugs corrected in the R interface

• A bug was corrected in write.pajek.bgraph.
• Several bugs were corrected in graph.adjacency.
• Pajek reader bug corrected, used to segfault if '*Vertices' was missing.
• Directedness is handled correctly when writing GML files. (But note that 'correct' conflicts the standard here.)
• Corrected a bug when calculating weighted, directed PageRank on an undirected graph. (Which does not make sense anyway.)
• Several bugs were fixed in the Reingold-Tilford layout to avoid edge crossings.
• A bug was fixed in the GraphML reader, when the value of a graph attribute was not specified.
• Fixed a bug in the graph isomorphism routine for small (3-4 vertices) graphs.
• Corrected the random sampling implementation (igraph_random_sample), now it always generates unique numbers. This affects the Gnm Erdos-Renyi generator, it always generates simple graphs now.
• The basic igraph constructor (igraph_empty_attrs, all functions are expected to call this internally) now checks whether the number of vertices is finite.
• The LGL, NCOL and Pajek graph readers handle errors properly now.
• The non-symmetric ARPACK solver returns results in a consistent form now.
• The fast greedy community detection routine now checks that the graph is simple.
• The LGL and NCOL parsers were corrected to work with all kinds of end-of-line encodings.
• Hub & authority score calculations initialize ARPACK parameters now.
• Fixed a bug in the Walktrap community detection routine, when applied to unconnected graphs.
• Several small memory leaks were removed, and a big one from the Spinglass community structure detection function

New in the Python interface

• A new layout generator called DrL.
• Uniform sampling of random connected undirected graphs with a given degree sequence.
• Methods parameters accepting igraph.IN, igraph.OUT and igraph.ALL constants now also accept these as strings ("in", "out" and "all"). Prefix matches also allowed as long as the prefix match is unique.
• Graph.shortest_paths() now supports edge weights (Dijkstra's and Bellman-Ford algorithm implemented)
• Graph.get_shortest_paths() also supports edge weights (only Dijkstra's algorithm yet)
• Added Graph.is_mutual() to find mutual edges in a directed graph.
• Added inverse log-weighted similarity measure (a.k.a. Adamic/Adar similarity).
• preference.game and asymmetric.preference.game were rewritten, they are O(|V|+|E|) now, instead of O(|V|^2).
• ARPACK options can now be modified from the Python interface (thanks to Kurt Jacobson)
• Layout.to_radial() added -- now you can create a top-down tree layout by the Reingold-Tilford algorithm and then turn it to a radial tree layout
• Added Graph.write_pajek() to save graphs in Pajek format
• Some vertex and edge related methods can now also be accessed via the methods of VertexSeq and EdgeSeq, restricted to the current vertex/edge sequence of course
• Visualisations now support triangle shaped vertices
• Added Graph.mincut()
• Added Graph.Weighted_Adjacency() to create graphs from weighted adjacency matrices
• Kamada-Kawai and Fruchterman-Reingold layouts now accept initial vertex positions
• Graph.Preference() and Graph.Asymmetric_Preference() were rewritten, they are O(|V|+|E|) now, instead of O(|V|^2).

Bugs corrected in the Python interface

• Graph.constraint() now properly returns floats instead of integers (thanks to Eytan Bakshy)
• Graphs given by adjacency matrices are now finally loaded and saved properly
• Graph.Preference() now accepts floats in type distributions
• A small bug in Graph.community_edge_betweenness() corrected
• Some bugs in numeric attribute handling resolved
• VertexSeq and EdgeSeq objects can now be subsetted by lists and tuples as well
• Fixed a bug when dealing with extremely small layout sizes
• Eigenvector centality now always return positive values
• Graph.authority_score() now really returns the authority scores instead of the hub scores (blame copypasting)
• Pajek reader bug corrected, used to segfault if '*Vertices' was missing.
• Directedness is handled correctly when writing GML files. (But note that 'correct' conflicts the standard here.)
• Corrected a bug when calculating weighted, directed PageRank on an undirected graph. (Which does not make sense anyway.)
• Several bugs were fixed in the Reingold-Tilford layout to avoid edge crossings.
• A bug was fixed in the GraphML reader, when the value of a graph attribute was not specified.
• Fixed a bug in the graph isomorphism routine for small (3-4 vertices) graphs.
• Corrected the random sampling implementation (igraph_random_sample), now it always generates unique numbers. This affects the Gnm Erdos-Renyi generator, it always generates simple graphs now.
• The LGL, NCOL and Pajek graph readers handle errors properly now.
• The non-symmetric ARPACK solver returns results in a consistent form now.
• The fast greedy community detection routine now checks that the graph is simple.
• The LGL and NCOL parsers were corrected to work with all kinds of end-of-line encodings.
• Hub & authority score calculations initialize ARPACK parameters now.
• Fixed a bug in the Walktrap community detection routine, when applied to unconnected graphs.
• Several small memory leaks were removed, and a big one from the Spinglass community structure detection function

New in the C layer

• A new layout generator called DrL.
• Uniform sampling of random connected undirected graphs with a given degree sequence.
• Some stochastic test results are ignored (for spinglass community detection, some Erdos-Renyi generator tests)
• Weighted shortest paths, Dijkstra's algorithm.
• The unweigthed shortest path routine returns 'Inf' for unreachable vertices.
• New function, igraph_adjlist can create igraph graphs from adjacency lists.
• New function, igraph_weighted_adjacency can create weighted graphs from weight matrices.
• New function, igraph_is_mutual to search for mutual edges.
• Added inverse log-weighted similarity measure (a.k.a. Adamic/Adar similarity).
• igraph_preference_game and igraph_asymmetric_preference_game were rewritten, they are O(|V|+|E|) now, instead of O(|V|^2).
• The Bellman-Ford shortest path algorithm was added.
• Added weighted variant of igraph_get_shortest_paths, based on Dijkstra's algorithm.
• Several small memory leaks were removed, and a big one from the Spinglass community structure detection function

Bugs corrected in the C layer

• Several bugs were corrected in the (still experimental) C attribute handler.
• Pajek reader bug corrected, used to segfault if '*Vertices' was missing.
• Directedness is handled correctly when writing GML files. (But note that 'correct' conflicts the standard here.)
• Corrected a bug when calculating weighted, directed PageRank on an undirected graph. (Which does not make sense anyway.)
• Some code polish to make igraph compile with GCC 4.3
• Several bugs were fixed in the Reingold-Tilford layout to avoid edge crossings.
• A bug was fixed in the GraphML reader, when the value of a graph attribute was not specified.
• Fixed a bug in the graph isomorphism routine for small (3-4 vertices) graphs.
• Corrected the random sampling implementation (igraph_random_sample), now it always generates unique numbers. This affects the Gnm Erdos-Renyi generator, it always generates simple graphs now.
• The basic igraph constructor (igraph_empty_attrs, all functions are expected to call this internally) now checks whether the number of vertices is finite.
• The LGL, NCOL and Pajek graph readers handle errors properly now.
• The non-symmetric ARPACK solver returns results in a consistent form now.
• The fast greedy community detection routine now checks that the graph is simple.
• The LGL and NCOL parsers were corrected to work with all kinds of end-of-line encodings.
• Hub & authority score calculations initialize ARPACK parameters now.x
• Fixed a bug in the Walktrap community detection routine, when applied to unconnected graphs.

igraph 0.5

Released February 14, 2008

See also the release notes at http://cneurocvs.rmki.kfki.hu/igraph/relnotes-0.5.html

New in the R interface

• The 'rescale', 'asp' and 'frame' graphical parameters were added
• Create graphs from a formula notation (graph.formula)
• Handle graph attributes properly
• Calculate the actual minimum cut for undirected graphs
• Adjacency lists, get.adjlist and get.adjedgelist added
• Eigenvector centrality computation is much faster now
• Proper R warnings, instead of writing the warning to the terminal
• R checks graphical parameters now, the unknown ones are not just ignored, but an error message is given
• plot.igraph has an 'add' argument now to compose plots with multiple graphs
• plot.igraph supports the 'main' and 'sub' arguments
• layout.norm is public now, it can normalize a layout
• It is possible to supply startup positions to layout generators
• Always free memory when CTRL+C/ESC is pressed, in all operating systems
• plot.igraph can plot square vertices now, see the 'shape' parameter
• graph.adjacency rewritten when creating weighted graphs
• We use match.arg whenever possible. This means that character scalar options can be abbreviated and they are always case insensitive
• VF2 graph isomorphism routines can check subgraph isomorphism now, and they are able to return matching(s)
• The BLISS graph isomorphism algorithm is included in igraph now. See canonical.permutation, graph.isomorphic.bliss
• We use ARPACK for eigenvalue/eigenvector calculation. This means that the following functions were rewritten: page.rank, leading.eigenvector.community.*, evcent. New functions based on ARPACK: hub.score, authority.score, arpack.
• Edge weights for Fruchterman-Reingold layout (layout.fruchterman.reingold).
• Line graph calculation (line.graph)
• Kautz and de Bruijn graph generators (graph.kautz, graph.de.bruijn)
• Support for writing graphs in DOT format
• Jaccard and Dice similarity coefficients added (similarity.jaccard, similarity.dice)
• Counting the multiplicity of edges (count.multiple)
• The graphopt layout algorithm was added, layout.graphopt
• Generation of "famous" graphs (graph.famous).
• Create graphs from LCF notation (graph.cf).
• Dyad census and triad cencus functions (dyad.census, triad.census)
• Cheking for simple graphs (is.simple)
• Create full citation networks (graph.full.citation)
• Create a histogram of path lengths (path.length.hist)
• Forest fire model added (forest.fire.game)
• DIMACS reader can handle different file types now
• Biconnected components and articulation points (biconnected.components, articulation.points)
• Kleinberg's hub and authority scores (hub.score, authority.score)
• as.undirected handles attributes now
• Geometric random graph generator (grg.game) can return the coordinates of the vertices
• Function added to convert leading eigenvector community structure result to a membership vector (community.le.to.membership)
• Weighted fast greedy community detection
• Weighted page rank calculation
• Functions for estimating closeness, betweenness, edge betweenness by introducing a cutoff for path lengths (closeness.estimate, betweenness.estimate, edge.betweenness.estimate)
• Weighted modularity calculation
• Function for permuting vertices (permute.vertices)
• Betweenness and closeness calculations are speeded up
• read.graph can handle all possible line terminators now (\r, \n, \r\n, \n\r)
• Error handling was rewritten for walktrap community detection, the calculation can be interrupted now
• The maxflow/mincut functions allow to supply NULL pointer for edge capacities, implying unit capacities for all edges

Bugs corrected in the R interface

• Fixed a bug in cohesive.blocks, cohesive blocks were sometimes not calculated correctly

New in the Python interface

• Added shell interface: igraph can now be invoked by calling the script called igraph from the command line. The script launches the Python interpreter and automatically imports igraph functions into the main namespace
• Pickling (serialization) support for Graph objects
• Plotting functionality based on the Cairo graphics library (so you need to install python-cairo if you want to use it). Currently the following objects can be plotted: graphs, adjacency matrices and dendrograms. Some crude support for plotting histograms is also implemented. Plots can be saved in PNG, SVG and PDF formats.
• Unified Graph.layout method for accessing layout algorithms
• Added interfaces to walktrap community detection and the BLISS isomorphism algorithm
• Added dyad and triad census functionality and motif counting
• VertexSeq and EdgeSeq objects can now be restricted to subsets of the whole network (e.g., you can select vertices/edges based on attributes, degree, centrality and so on)

New in the C library

• Many types (stack, matrix, dqueue, etc.) are templates now They were also rewritten to provide a better organized interface
• VF2 graph isomorphism routines can check subgraph isomorphism now, and they are able to return matching(s)
• The BLISS graph isomorphism algorithm is included in igraph now. See igraph_canonical_permutation, igraph_isomorphic_bliss
• We use ARPACK for eigenvalue/eigenvector calculation. This means that the following functions were rewritten: igraph_pagerank, igraph_community_leading_eigenvector_*. New functions based on ARPACK: igraph_eigenvector_centrality, igraph_hub_score, igraph_authority_score, igraph_arpack_rssolve, igraph_arpack_rnsolve
• Experimental C attribute interface added. I.e. it is possible to use graph/vertex/edge attributes from C code now.
• Edge weights for Fruchterman-Reingold layout.
• Line graph calculation.
• Kautz and de Bruijn graph generators
• Support for writing graphs in DOT format
• Jaccard and Dice similarity coefficients added
• igraph_count_multiple added
• igraph_is_loop and igraph_is_multiple "return" boolean vectors
• The graphopt layout algorithm was added, igraph_layout_graphopt
• Generation of "famous" graphs, igraph_famous
• Create graphs from LCF notation, igraph_lcf, igraph_lcf_vector
• igraph_add_edge adds a single edge to the graph
• Dyad census and triad cencus functions added
• igraph_is_simple added
• progress handlers are allowed to stop calculation
• igraph_full_citation to create full citation networks
• igraph_path_length_hist, create a histogram of path lengths
• forest fire model added
• DIMACS reader can handle different file types now
• Adjacency list types made public now (igraph_adjlist_t, igraph_adjedgelist_t)
• Biconnected components and articulation points can be computed
• Eigenvector centrality computation
• Kleinberg's hub and authority scores
• igraph_to_undirected handles attributes now
• Geometric random graph generator can return the coordinates of the vertices
• Function added to convert leading eigenvector community structure result to a membership vector (igraph_le_community_to_membership)
• Weighted fast greedy community detection
• Weighted page rank calculation
• Functions for estimating closeness, betweenness, edge betweenness by introducing a cutoff for path lengths
• Weighted modularity calculation
• igraph_permute_vertices added
• Betweenness ans closeness calculations are speeded up
• Startup positions can be supplied to the Kamada-Kawai layout algorithms
• igraph_read_graph_* functions can handle all possible line terminators now (\r, \n, \r\n, \n\r)
• Error handling was rewritten for walktrap community detection, the calculation can be interrupted now
• The maxflow/mincut functions allow to supply a null pointer for edge capacities, implying unit capacities for all edges

Bugs corrected in the C library

• Memory leak fixed in adjacency list handling
• Memory leak fixed in maximal independent vertex set calculation
• Fixed a bug when rewiring undirected graphs with igraph_rewire
• Fixed edge betweenness community structure detection for unconnected graphs
• Make igraph compile with Sun Studio
• Betweenness bug fixed, when not computing for all vertices
• memory usage of clique finding reduced
• Corrected bugs for motif counts when not all motifs were counted, but a 'cut' vector was used
• Bugs fixed in trait games and cited type game
• Accept underscore as letter in GML files
• GML file directedness notation reversed, more logical this way

igraph 0.4.5

Released January 1, 2008

New:

• Cohesive block finding in the R interface, thanks to Peter McMahan for contributing his code. See James Moody and Douglas R. White, 2003, in Structural Cohesion and Embeddedness: A Hierarchical Conception of Social Groups American Sociological Review 68(1):1-25
• Biconnected components and articulation points.
• R interface: better printing of attributes.
• R interface: graph attributes can be used via '$'.

New in the C library:

• igraph_vector_bool_t data type.

Bug fixed:

• Erdos-Renyi random graph generators rewritten.

igraph 0.4.4

Released October 3, 2007

This release should work seemlessly with the new R 2.6.0 version. Some other bugs were also fixed:

• A bug was fixed in the Erdos-Renyi graph generator, which sometimes added an extra vertex.
• MSVC compilation issues were fixed.
• MinGW compilation fixes.

igraph 0.4.3

Released August 13, 2007

The next one in the sequence of bugfix releases. Thanks to many people sending bug reports. Here are the changes:

• Some memory leaks removed when using attributes from R or Python.
• GraphML parser: entities and character data in multiple chunks are now handled correctly.
• A bug corrected in edge betweenness community structure detection, it failed if called many times from the same program/session.
• Bug corrected in 'adjacent edges' edge iterator.
• Python interface: edge and vertex attribute deletion bug corrected.
• Edge betweeness community structure: handle unconnected graphs properly.
• Fixed bug related to fast greedy community detection in unconnected graphs.
• Use a different kind of parser (Push) for reading GraphML files. This is almost invisible for users but fixed a nondeterministic bug when reading in GraphML files.
• R interface: plot now handles properly if called with a vector as the edge.width argument for directed graphs.
• R interface: bug (typo) corrected for walktrap.community and weighted graphs.
• Test suite should run correctly on Cygwin now.

igraph 0.4.2

Released June 7, 2007

This is another bugfix release, as there was a serious bug in the R package of the previous version: it could not read and write graphs to files in any format under MS Windows.

Some other bits added:

• circular Reingold-Tilford layout generator for trees
• corrected a bug, Pajek files are written properly under MS Windows now.
• arrow.size graphical edge parameter added in the R interface.

igraph 0.4.1

Released May 23, 2007

This is a minor release, it corrects a number of bugs, mostly in the R package.

igraph 0.4

Released 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 C library

• internal representation changed
• neighbors always returns an ordered list
• igraph_is_loop and igraph_is_multiple added
• topological sorting
• VF2 isomorphism algorithm
• support for reading the file format of the Graph Database for isomorphism
• igraph_mincut cat calculate the actual minimum cut
• 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
• igraph_community_to_membership supporting function added, creates a membership vector from a community structure merge tree
• modularity calculation added

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.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

• proper support for Debian packages (re)added
• 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

Debian package repository available

Debian Linux users can now install and update the C interface using the standard package manager. Just add the following two lines to /etc/apt/sources.list and install the libigraph and libigraph-dev packages. Packages for the Python interface are coming soon.

deb http://cneurocvs.rmki.kfki.hu /packages/binary/

deb-src http://cneurocvs.rmki.kfki.hu /packages/source/

Python interface documentation

Jan 8, 2007

The documentation of the Python interface is available. See section 'documentation' in the menu on the left.

igraph 0.3.2

Released Dec 19, 2006

This is a new major release, it contains many new things:

Changes in the C library

• igraph_maxdegree added, calculates the maximum degree in the graph
• igraph_grg_game, geometric random graphs
• igraph_density, graph density calculation
• push-relabel maximum flow algorithm added, igraph_maxflow_value
• minimum cut functions added based on maximum flow: igraph_st_mincut_value, igraph_mincut_value, the Stoer-Wagner algorithm is implemented for undirected graphs
• vertex connectivity functions, usually based on maximum flow: igraph_st_vertex_connectivity, igraph_vertex_connectivity
• edge connectivity functions, usually based on maximum flow: igraph_st_edge_connectivity, igraph_edge_connectivity
• other functions based on maximum flow: igraph_edge_disjoint_paths, igraph_vertex_disjoint_paths, igraph_adhesion, igraph_cohesion
• dimacs file format added
• igraph_to_directed handles attributes
• igraph_constraint calculation corrected, it handles weighted graphs
• spinglass-based community structure detection, the Joerg Reichardt -- Stefan Bornholdt algorithm added: igraph_spinglass_community, igraph_spinglass_my_community
• igraph_extended_chordal_rings, it creates extended chordal rings
• 'no' argument added to igraph_clusters, it is possible to calculate the number of clusters without calculating the clusters themselves
• minimum spanning tree functions keep attributes now and also the direction of the edges is kept in directed graphs
• there are separate functions to calculate different types of transitivity now
• igraph_delete_vertices rewritten to allocate less memory for the new graph
• neighborhood related functions added: igraph_neighborhood, igraph_neighborhood_size, igraph_neighborhood_graphs
• two new games added based on different node types: igraph_preference_game and igraph_asymmetric_preference_game
• Laplacian of a graph can be calculated by the igraph_laplacian function

Changes in the R interface

• bonpow function ported from SNA to calculate Bonacich power centrality
• get.adjacency supports attributes now, this means that it sets the colnames and rownames attributes and can return attribute values in the matrix instead of 0/1
• grg.game, geometric random graphs
• graph.density, graph density calculation
• edge and vertex attributes can be added easily now when added new edges with add.edges or new vertices with add.vertices
• graph.data.frame creates graph from data frames, this can be used to create graphs with edge attributes easily
• plot.igraph and tkplot can plot self-loop edges now
• graph.edgelist to create a graph from an edge list, can also handle edge lists with symbolic names
• get.edgelist has now a 'names' argument and can return symbolic vertex names instead of vertex ids, by default id uses the 'name' vertex attribute is returned
• printing graphs on screen also prints symbolic symbolic names (the 'name' attribute if present)
• maximum flow and minimum cut functions: graph.maxflow, graph.mincut
• vertex and edge connectivity: edge.connectivity, vertex.connectivity
• edge and vertex disjoint paths: edge.disjoint.paths, vertex.disjoint.paths
• White's cohesion and adhesion measure: graph.adhesion, graph.cohesion
• dimacs file format added
• as.directed handles attributes now
• constraint corrected, it handles weighted graphs as well now
• weighted attribute to graph.adjacency
• spinglass-based community structure detection, the Joerg Reichardt -- Stefan Bornholdt algorithm added: spinglass.community
• graph.extended.chordal.ring, extended chordal ring generation
• no.clusters calculates the number of clusters without calculating the clusters themselves
• minimum spanning tree functions updated to keep attributes
• transitivity can calculate local transitivity as well
• neighborhood related functions added: neighborhood, neighborhood.size, graph.neighborhood
• new graph generators based on vertex types: preference.game and asymmetric.preference.game

Bugs corrected

• attribute handling bug when deleting edges corrected
• GraphML escaping and NaN handling corrected
• bug corrected to make it possible compile the R package without the libxml2 library
• a bug in Erdos-Renyi graph generation corrected: it had problems with generating large directed graphs
• bug in constraint calculation corrected, it works well now
• fixed memory leaks in igraph_read_graph_graphml
• error handling bug corrected in igraph_read_graph_graphml
• bug corrected in R version of graph.laplacian when normalized Laplacian is requested
• memory leak corrected in get.all.shortest.paths in the R package

igraph 0.2.1

Released Aug 23, 2006

This is a bug-fix release. Bugs fixed:

• igraph_reciprocity (reciprocity in R) corrected to avoid segfaults
• some docs updates
• various R package updated to make it conform to the CRAN rules

igraph 0.2

Released Aug 18, 2006

Release time at last! There are many new things in igraph 0.2, the most important ones:

• reading writing Pajek and GraphML formats with attributes (not all Pajek and GraphML files are supported, see documentation for details)
• iterators totally rewritten, it is much faster and cleaner now
• the RANDEDU fast motif search algorithm is implemented
• many new graph generators, both games and regular graphs
• many new structural properties: transitivity, reciprocity, etc.
• graph operators: union, intersection, difference, structural holes, etc.
• conversion between directed and undirected graphs
• new layout algorithms for trees and large graphs, 3D layouts

and many more.

New things in the R package:

• support for CTRL+C
• new functions: Graph Laplacian, Burt's constraint, etc.
• vertex/edge sequences totally rewritten, smart indexing (see manual)
• new R manual and tutorial: `Network Analysis with igraph', still under development but useful
• very basic 3D plotting using OpenGL

Although this release was somewhat tested on Linux, MS Windows, Mac OSX, Solaris 8 and FreeBSD, no heavy testing was done, so it might contain bugs, and we kindly ask you to send bug reports to make igraph better.

igraph mailing lists

Aug 18, 2006

I've set up two igraph mailing lists: igraph-help for general igraph questions and discussion and igraph-anonunce for announcements. See http://lists.nongnu.org/mailman/listinfo/igraph-help and http://lists.nongnu.org/mailman/listinfo/igraph-announce for subscription information, archives, etc.

igraph 0.1

Released Jan 30, 2006

After about a year of development this is the first "official" release of the igraph library. This release should be considered as beta software, but it should be useful in general. Please send your questions and comments.