Changelog
Source:NEWS.md
igraph 1.5.1.9002
Chore
Bump upcoming igraph/C 0.10 sources.
Bump upcoming igraph/C 0.10 sources.
Breaking change: Remove some behaviour / parameters that were deprecated in 1.3 (#842).
Breaking changes
 Breaking change: Remove some behaviour / parameters that were deprecated in 1.3 (#842).
igraph 1.5.1
CRAN release: 20230810
Breaking changes
 Breaking change: start deprecation of
estimate_betweenness()
,estimate_edge_betweenness()
,estimate_closeness()
(#852).
Bug fixes

identical_graphs()
now correctly detects identical graphs without node or edge attributes (#757).
Internal
Change ownership rules of attribute objects (#870).
R_SEXP_to_igraph()
andR_SEXP_to_igraph_copy()
getigraph_t
object from external pointer (#865).Remove
ETIME()
call from Fortran code, already in CRAN version 1.5.0.1 (#858).Ensure that
_GNU_SOURCE
is always defined (#877).Fix
make clean
(#860).Fix generation of code for functions with
VERTEX_COLOR
outarguments (#850).Use
lquadmath
inMakevars.win
, for compatibility with alternative R distributions such as Microsoft R Open (#855).getRversion()
uses strings.
Documentation
Add cffr file and a GHA workflow that updates it automatically (#873).
Undeprecate
neighborhood()
(#851).Remove redundant reference to AUTHORS from DESCRIPTION.
Refactoring
 Breaking change: start deprecation of
estimate_betweenness()
,estimate_edge_betweenness()
,estimate_closeness()
(#852).
igraph 1.5.0
CRAN release: 20230616
Breaking changes
The internal format of graph objects has changed in a mostly backwardcompatible way, to prepare for upgrading the C core to 0.10. Details are described at https://github.com/igraph/rigraph/wiki/Theigraphobjectformat. Accessing graph objects that have been created with an older igraph version give a clean error message with instructions (#832). The new format cannot be read by igraph 1.4.3 or older, the following error is raised when trying to do so:
This graph was created by an old(er) igraph version.
Call upgrade_graph() on it to use with the current igraph version
For now we convert it on the fly...
Error in is_directed(object) :
REAL() can only be applied to a 'numeric', not a 'NULL'
The only supported remedy is to upgrade the igraph package to version 1.5.0 or later.
graph_version()
now returns an integer scalar (#832, #847), 4
as of igraph 1.5.0 (#835).
Features
Vertex and edge sequences are converted to numeric vectors when used in attributes (#808).
New
largest_component()
returns the largest connected component (#786, @ngmaclaren).
Bug fixes
 Fix error message in
make_graph()
whensimplify = ...
is used with a nonformula (#834).
Testing
Add more tests for
graph_from_literal()
(#826).Reenable serialization test and tests for
dyad_census()
, stabilize tests (#809, #822, #823).
Documentation
The documentation for the R package is now hosted at https://r.igraph.org/ (#780).
Fix use of deprecated functions in examples, e.g., replace
gsize()
byecount()
(#827).Fix typos in
?eigen_centrality
docs (@JJ).Add DOI to CITATION (#773).
igraph 1.4.3
CRAN release: 20230522
Documentation
 Mention limitation of Pajek reader (#776).
igraph 1.4.2
CRAN release: 20230407
Breaking changes
Remove
igraph.eigen.default()
andeigen_defaults
, introduce internaleigen_defaults()
as a function (#741).Remove broken
nexus*()
functions (#705), andsrand()
(#701).
C core
Update C core.
ARPACKbased calculations are now interruptible.
shortest_paths()
andall_shortest_paths()
no longer crash when an invalidfrom
vertex is passed and weights are being used.
See diff for details.
Bug fixes
as_long_data_frame()
now correctly processes vertex attributes and works with graphs without vertex attributes (#748).as.hclust(hrg.fit(g))
works again (#721).
Documentation
The documentation is now available at https://igraph.org/ (#743).
Reorganize function reference (#662).
Replace
graph()
withmake_graph()
in examples (#738).Add docs for
as.hclust.igraphHRG()
(#733).Merged man page of
hub_score()
andauthority_score()
(#698).Refactor contributors listing (#647).
Improve “family” titles (#679).
Improve docs of ego/neighborhood functions.
Improve
transitivity()
docs.
igraph 1.4.1
CRAN release: 20230224
Bug fixes
console()
now works again and provides a Tcl/Tk based UI where igraph can post status messages and progress info (#664).Fix errors when printing long vertex names (#677, @ahmohamed).
Fix regression that broke builds on some systems (e.g., GCC version 5 or earlier), introduced in igraph 1.4.0 (#670, #671).
fit_hrg()
does not crash any more when called with a graph that has less than three vertices.
Internal
Fix warning about
yyget_leng()
returning wrong type when using LTO (#676).Don’t mention C++11 or C++17 for best compatibility with both newest R and older compilers, while still requesting a C++ compiler for linking.
Don’t ignore
build/
when building the package because the vignette index is built there.Skip plot test entirely on Rdevel.
Avoid submodules for building igraph (#674).
Makevars cleanup (#671).
Add Zenodo configuration file.
igraph 1.4.0
CRAN release: 20230210
Breaking changes
 Breaking change: Allow change of attribute type when setting attribute for all vertices or edges; only attributes of length 1 or the length of the target set allowed (#633).
Added

tkplot()
gained apalette
argument and it is now using the same palette asplot()
by default, for sake of consistency. 
plot.igraph()
gained aloop.size
argument that can be used to scale the common radius of the loop edges.
Fixed
 The default maximum number of iterations for ARPACK has been increased to 3000 to match that of the igraph C core.
 Rare convergence problems have been corrected in
cluster_leading_eigen()
.  All ARPACKbased functions now respect random seeds set in R when generating a random starting vector.

igraph_version()
returned an invalid value in 1.3.4, this is now corrected.  The value of
par(xpd=...)
is now restored after plotting a graph.  Fixed a bug in
as.dendrogram.communities()
for large dendrograms, thanks to @pkharchenko (see PR #292).  Fixed two bugs in
graph_from_incidence_matrix()
that prevented the creation of directed graphs withmode="all"
from dense or sparse matrices. 
dfs()
accidentally returned zerobased root vertex indices in the result object; this is now fixed and the indices are now 1based. 
as_graphnel()
does not duplicate loop edges any more. 
as_graphnel()
now checks that the input graph has no multiedges. Multiedges are not supported by the graphNEL class. 
convex_hull()
now returns the vertices of the convex hull with 1based indexing.  Some
rgl.*()
function calls in the codebase were replaced with equivalent*3d()
function calls in preparation for upcoming deprecations inrgl
(see PR #619) 
plot.igraph()
does not use theframe=...
partial argument any more when callingplot.default()
. The defaultNULL
value offrame.plot
is now also handled correctly. 
hub_score()
andauthority_score()
considered selfloops only once on the diagonal of the adjacency matrix of undirected graphs, thus the result was not identical to that obtained byeigen_centrality()
on loopy undirected graphs. This is now corrected. 
distances()
no longer ignores themode
parameter whenalgorithm='johnson'
.
Deprecated

automorphisms()
was renamed tocount_automorphisms()
; the old name is still available, but it is deprecated.
Other
 Documentation improvements.
 The Github repository was now moved to a singlebranch setup where the package can be built from the
main
branch directly.  Added igraph extended tutorial as an R vignette (#587).
 igraph now has a homepage based on
pkgdown
thanks to @maelle (see #645). This will eventually become the official homepage.
igraph 1.3.5
CRAN release: 20220922
Added:

mark.groups=...
argument ofplot.igraph()
now acceptscommunities
objects
Fixed:
Negative degree exponents are not allowed any more in
sample_pa()
andsample_aging_pa()
.Package updated to be compatible with Matrix 1.5.
Other:
 Documentation improvements and fixes.
igraph 1.3.4
CRAN release: 20220719
Added:

sample_asym_pref()
now returns the generated types of the vertices in the vertex attributes namedouttype
andintype
.
Fixed:
layout_nicely()
does not recurse infinitely any more if it is assigned to thelayout
attribute of a graphlayout_nicely()
now ignores edge weights when there are nonpositive edge weights. This is needed because igraph 1.3.3 started validating edge weights inlayout_with_fr()
andlayout_with_drl()
, resulting in errors whenlayout_nicely()
was used on weighted graphs with negative weights. Sincelayout_nicely()
is the default layout algorithm forplot()
, most users were not even aware that they were using the FR or DrL layouts behind the scenes. Now the policy is thatlayout_nicely()
attempts to get the job done without errors if possible, even if that means that edge weights must be ignored. A warning is printed if this is the case.
igraph 1.3.3
CRAN release: 20220714
Added:
reverse_edges()
reverses specific or all edges in a graph.Singlebracket indexing of
V()
andE()
resolves attribute names in the indexing expressions by default (for instance,E(g)[weight > x]
matches edges with a weight larger than a threshold). This can be problematic if the attribute masks one of the variables in the local evaluation context. We now have a pronoun called.env
(similarly torlang::.env
) that allows you to force attribute name lookup to the calling environment. For sake of completeness, we also provide.data
(similarly torlang::.data
) to force attribute name lookup to the vertex / edge attributes only. These pronouns are automatically injected into the environment where the indexing expression is evaluated.
Deprecated:
 Names of functions that can be used inside a
V()
orE()
indexing start with a dot since igraph 1.1.1; however, the old dotless names did not print a deprecation warning so this may have gone unnoticed for years. We are introducting a deprecation warning fornei()
,innei()
,outnei()
,inc()
,from()
andto()
inside singlebracket indexing of vertex and edge sequences and will remove the old variants soon.
igraph 1.3.2
CRAN release: 20220613
The C core is updated to 0.9.9, fixing a range of bugs.
Fixed:
 The length of sizezero
communities
objects is now reported correctly. 
layout_with_kk()
would fail to produce reasonable results with the default initial coordinates. This has been corrected, however, this function no longer produces precisely the same output for a given graph as before. To restore the previous behaviour, uselayout_with_kk(g, coord=layout_in_circle(g))
in 2D orlayout_with_kk(g, dim=3, coord=layout_on_sphere(g))
in 3D.  Indexing an
igraph.vs
object withv[x, na_ok=T]
now correctly handles thena_ok
argument in all cases; previous versions ignored it whenx
was a single number.
Other:
 Documentation improvements and fixes.
igraph 1.3.1
CRAN release: 20220420
Fixed:

graph_from_adjacency_matrix()
now works with sparse matrices even if the cell values in the sparse matrix are unspecified.  Fixed crash in
cluster_walktrap()
whenmodularity=FALSE
andmembership=FALSE
. 
cluster_walktrap()
no longer accepts invalid weight vectors. 
cluster_walktrap()
no longer returns a modularity vector of invalid length for disconnected graphs. This also fixes some rare failures of this function on weighted disconnected graphs. 
edge_attr()
does not ignore itsindex=...
argument any more. 
automorphisms()
,automorphism_group()
andcanonical_permutation()
now allow all possible values supported by the C core in thesh
argument. Earlier versions supported only"fm"
.  The
vertex.frame.width
plotting parameter now allows zero and negative values; these will simply remove the outline of the corresponding vertex.  The documentation of the
sh
argument of the BLISS isomorphism algorithm inisomorphic()
was fixed; earlier versions incorrectly referred tosh1
andsh2
. 
dominator_tree()
now conforms to its documentation with respect to thedom
component of the result: it contains the indices of the dominator vertices for each vertex and1
for the root of the dominator tree.  Mentions of the
"power"
algorithm ofpage_rank()
have been removed from the documentation, as this method is no longer available.  Several other documentation fixes to bring the docs up to date with new behaviours in igraph 1.3.
igraph 1.3.0
CRAN release: 20220401
The C core is updated to 0.9.7, fixing a range of bugs and introducing a number of new functions.
Added:

has_eulerian_path()
andhas_eulerian_cycle()
decides whether there is an Eulerian path or cycle in the graph. 
eulerian_path()
andeulerian_cycle()
returns the edges and vertices in an Eulerian path or cycle in the graph. 
any_loop()
checks whether a graph contains at least one loop edge. 
is_tree()
checks whether a graph is a tree and also finds a possible root 
to_prufer()
converts a tree graph into its Prufer sequence 
make_from_prufer()
creates a tree graph from its Prufer sequence 
sample_tree()
to sample labelled trees uniformly at random 
sample_spanning_tree()
to sample spanning trees of an undirected graph uniformly at random 
automorphisms()
andcanonical_permutation()
now supports vertex colors 
random_edge_walk()
to record the edges traversed during a random walk 
harmonic_centrality()
calculates the harmonic centrality of vertices, optionally with a cutoff on path lengths 
mean_distance()
now supports edge weights and it can also return the number of unconnected vertex pairs whendetails=TRUE
is passed as an argument 
greedy_vertex_coloring()
finds vertex colorings based on a simple greedy algorithm. 
bridges()
finds the bridges (cutedges) of a graph  The frame width of circle, rectangle and square vertex shapes can now be adjusted on plots with the
frame.width
vertex attribute or thevertex.frame.width
keyword argument, thanks to @simoncarrignon . See PR #500 for more details. 
automorphism_group()
returns a possible (not necessarily minimal) generating set of the automorphism group of a graph. 
global_efficiency()
calculates the global efficiency of the graph. 
local_efficiency()
calculates the local efficiency of each vertex in a graph. 
average_local_efficiency()
calculates the average local efficiency across the set of vertices in a graph. 
rewire(each_edge(...))
now supports rewiring only one endpoint of each edge. 
realize_degseq()
generates graphs from degree sequences in a deterministic manner. It is also available asmake_(degseq(..., deterministic=TRUE))
. 
clique_size_counts()
counts cliques of different sizes without storing them all. 
feedback_arc_set()
finds a minimumweight feedback arc set in a graph, either with an exact integer programming algorithm or with a lineartime approximation. 
make_bipartite_graph()
now handles vertices with names. 
shortest_paths()
now supports graphs with negative edge weights. 
min_cut()
now supports st mincuts even ifvalue.only=FALSE
. 
as.matrix()
now supports converting an igraph graph to an adjacency or edge list matrix representation. Seeas.matrix.igraph()
for more details. This function was migrated fromintergraph
; thanks to Michal Bojanowski.
Fixed:

is_connected()
now returns FALSE for the null graph  Calling
length()
on a graph now returns the number of vertices to make it consistent with indexing the graph with[[
. 
diameter()
now corrently returns infinity for disconnected graphs whenunconnected=FALSE
. Previous versions returned the number of vertices plus one, which was clearly invalid for weighted graphs. 
mean_distance()
now correctly treats the path length between disconnected vertices as infinite whenunconnected=FALSE
. Previous versions used the number of vertices plus one, adding a bias towards this number, even if the graph was weighted and the number of vertices plus one was not a path length that could safely have been considered as being longer than any “valid” path. 
layout_with_sugiyama()
now handles the case of exactly one extra virtual node correctly; fixes #85 
bfs()
anddfs()
callback functions now correctly receive 1based vertex indices and ranks; it used to be zerobased in earlier versions  Accidentally returning a nonlogical value from a
bfs()
ordfs()
callback does not crash R any more  Calling
print()
on a graph with a smallmax.lines
value (smaller than the number of lines needed to print the attribute list and the header) does not raise an error any more; fixes #179 
as_adjacency_matrix(edges=TRUE, sparse=TRUE)
now consistently returns the last edge ID for each cell in the matrix instead of summing them.  Using the
+
and
operators with apath()
object consisting of two vertices is now handled correctly; fixes #355 
topo_sort()
now throws an error if the input graph is not acyclic instead of returning an incorrect partial ordering.  Weighted transitivity calculations (i.e.
transitivity(mode="barrat")
now throw an error for multigraphs; the implementation does not work correctly for multigraphs and earlier versions did not warn about this.
Changed:
 The
neimode
argument ofbfs()
anddfs()
was renamed tomode
for sake of consistency with other functions. The old argument name is deprecated and will be removed in 1.4.0. 
bfs()
anddfs()
callback functions now correctly receive 1based vertex indices and ranks; it used to be zerobased in earlier versions. (This is actually a bugfix so it’s also mentioned in the “Fixed” section). 
closeness()
,betweenness()
andedge_betweenness()
now all take acutoff
argument on their own.estimate_closeness()
,estimate_betweenness()
andestimate_edge_betweenness()
became aliases, with identical signature. They are not deprecated but their implementation might change in future versions to provide proper estimation schemes instead of a simple cutoffbased approximation. If you explicitly need cutoffs and you want your results to be reproducible with future versions, usecloseness()
,betweenness()
andedge_betweenness()
in your code with acutoff
argument. 
closeness()
now only considers reachable vertices during the calculation; in other words, closeness centrality is now calculated on a percomponent basis for disconnected graphs. Earlier versions considered all vertices.
Deprecated:
 Using
cutoff=0
forcloseness()
,betweenness()
andedge_betweenness()
is deprecated; if you want exact scores, use a negative cutoff.cutoff=0
will be interpreted literally from igraph 1.4.0. 
centr_degree_tmax()
now prints a warning when it is invoked without an explicitloops
argument.loops
will be mandatory from igraph 1.4.0.  The
nexus_list()
,nexus_info()
,nexus_get()
andnexus_search()
functions now return an error informing the user that the Nexus graph repository has been taken offline (actually, several years ago). These functions will be removed in 1.4.0.  The
edges
argument ofas_adjacency_matrix()
is deprecated; it will be removed in igraph 1.4.0.
Removed:
 The deprecated
page_rank_old()
function and the deprecatedpower
method ofpage_rank()
were removed.
igraph 1.2.10
CRAN release: 20211215
Dec 14, 2021
Fixed:
 The macOS versions of
igraph
were accidentally built without GraphML support on CRAN; this should now be fixed.
igraph 1.2.7
CRAN release: 20211015
Oct 15, 2021
The C core is updated to 0.8.5, fixing a range of bugs and introducing a number of new functions.
Added:
Fixed:

make_lattice()
correctly roundslength
to the nearest integer while printing a warning (#115). 
make_empty_graph(NULL)
now prints an error instead of producing an invalid graph (#404). 
make_graph(c())
now produces an empty graph instead of printing a misleading error message (#431).  Printing a graph where some edges have NA as the names of both endpoints does not produce a misleading error message any more (#410).
 The
types
argument of functions related to bipartite graphs now prints a warning when the types are coerced to booleans (#476).  Betweenness normalisation no longer overflows (#442).

layout_with_sugiyama()
returns a layout of type matrix even if there is only one vertex in the graph (#408).  Plotting a null graph (i.e. a graph with no vertices) does not throw an error any more (#387).
Deprecated:
 The
membership
argument ofmodularity.matrix()
is now deprecated as the function never needed it anyway. 
modularity()
now prints a warning when it is applied on a directed graph because the implementation in igraph’s C core does not support directed graphs as of version 0.8.5. The warning will be turned into an error in the next minor (1.3.0) version of the R interface; the error will be removed later when the C core is updated to a version that supports modularity for directed networks. 
transitivity()
now prints a warning when its local variant (type="local"
) is called on a directed graph or a graph with multiple edges beecause the implementation in the C core of igraph does not work reliably in these cases as of version 0.8.5. The warning will be turned into an error in the next minor (1.3.0) version of the R interface; the error will be removed later when the C core is updated to a version that supports transitivity for networks with multiple edges.
Misc:
 Documentation improvements.
igraph 1.2.1
CRAN release: 20180310
 The GLPK library is optional, if it is not available, then the
cluster_optimal()
function does not work. Unfortunately we cannot bundle the GLPK library into igraph on CRAN any more, because CRAN maintainers forbid the pragmas in its source code.  Removed the NMF package dependency, and related functions.
 Fix compilation without libxml2
igraph 1.1.1
CRAN release: 20170716
Jul 13, 2017
 Graph id is printed in the header, and a
graph_id
function was added  Fix
edge_attr
for some index values  Fix a
bfs()
bug,restricted
argument was zerobased 
match_vertices
is exported now 
%>%
is reexported in a better way, to avoid interference with other packages 
ego_
functions default toorder = 1
now  New function
igraph_with_opt
to run code with temporary igraph options settings  Fix broken
sample_asym_pref
function  Fix
curve_multiple
to avoid warnings for graphs with selfloops.  The
NMF
package is only suggested now, it is not a hard dependency  Fix gen_uid.c _SVID_SOURCE issues
 Avoid drawing straight lines as Bezier curves
 Use the
pkgconfig
package for options. This allows setting options on a perpackage basis. E.g. a package using igraph can setreturn.vs.es
toFALSE
in its.onLoad()
function, and then igraph will return plain numeric vectors instead of vertex/edge sequences if called from this package. 
igraph_options()
returns the old values of the updated options, this is actually useful, returning the new values was not. 
with_igraph_opt()
function to temporarily change values of igraph options. 
get.edge()
is deprecated, useends()
instead. (This was already the case for igraph 1.0.0, but we forgot to add a NEWS point for it.)  Do not redefine
.Call()
, to make native calls faster.  Speed up special cases of indexing vertex sequences.
 Removed an
anyNA()
call, to be compatible with older R versions.  Fixed a fastgreedy community finding bug, https://github.com/igraph/igraph/issues/836
 Fixed
head_of()
andtail_of()
, they were mixed up.  Plot: make
label.dist
independent of label lengths, fixes #63.  Plot: no error for unknown graphical parameters.
 Import functions from base packages, to eliminate
R CMD check
NOTE
s.  Readd support for edge weights in FruchtermanReingold layout
 Check membership vector in
modularity()
.  Rename
str.igraph()
toprint_all()
.  Use the igraph version in exported graphs, instead of @VERSION@ #75.
 Functions that can be used inside a
V()
orE()
indexing now begin with a dot. Old names are deprecated. New names:.nei()
,.innei()
,.outnei()
,.inc()
,.from()
,.to()
. #22  Fix packages that convert graphs to graph::graphNEL: they don’t need to attach ‘graph’ manually any more.
 Fix a bugs in
layout_with_dh
,layout_with_gem
andlayout_with_sugiyama
. They crashed in some cases.
igraph 1.0.1
CRAN release: 20150626
June 26, 2015
Some minor updates:
 Documentation fixes.
 Do not require a C++11 compiler any more.
 Fedora, Solaris and Windows compilation fixes.
igraph 1.0.0
CRAN release: 20150624
June 21, 2015
Release notes
This is a new major version of igraph, and then why not call it 1.0.0. This does not mean that it is ready, it’ll never be ready.
The biggest changes in the release are  the new function names. Most functions were renamed to make them more consistent and readable. (Relax, old names can still be used, no need to update any code.)  Better operations for vertex and edge sequences. Most functions return proper vertex/edge sequences instead of numeric ids.  The versatile make_()
and make_graph()
functions to create graphs.
Major changes
 Many functions were renamed. Old names are not documented, but can still be used.
 A generic
make_graph()
function to create graphs.  A generic
layout_()
(not the underscore!) function to create graph layouts, see alsoadd_layout_()
.  The igraph data type has changed. You need to call
upgrade_graph()
on graphs created with previous igraph versions.  Vertex and edge sequence operations: union, intersection, etc.
 Vertex and edge sequences can only be used with the graphs they belong to. This is now strictly checked.
 Most functions that return a (sub)set of vertices or edges return vertex or edge sequences instead.
 Vertex and edge sequences have a
[[
operator now, for easy viewing of vertex/edge metadata.  Vertex and edge sequences are implemented as weak references. See also the
as_ids()
function to convert them to simple ids.  Vertex order can be specified for the circle layout now.
 DavidsonHarel layout algorithm
layout_with_dh()
.  GEM layout algorithm
layout_with_gem()
.  Neighborhood functions have a
mindist
parameter for the smallest distance to consider. 
all_simple_paths()
function to list all simple paths in a graph. 
triangles()
lists all triangles in a graph.  FruchtermanReingold and KamadaKawai layout algorithms rewritten from scratch. They are much faster and follow the original publications closely.
 Nicer printing of graphs, vertex and edge sequences.

local_scan()
function calculates scan statistics.  Embeddings:
embed_adjacency_matrix()
andembed_laplacian_matrix()
.  Product operator:
*
, the same graph multiple times. Can be also used asrep()
.  Better default colors, color palettes for vertices.
 Random walk on a graph:
random_walk()

adjacent_vertices()
andincident_edges()
functions, they are vectorized, as opposed toneighhors()
andincident()
.  Convert a graph to a long data frame with
as_long_data_frame()
.
igraph 0.7.1
CRAN release: 20140422
April 21, 2014
Release Notes
Some bug fixes, to make sure that the code included in ‘Statistical Analysis of Network Data with R’ works. See https://github.com/kolaczyk/sand
Detailed changes:
 Graph drawing: fix labels of curved edges, issue #181.
 Graph drawing: allow fixing edge labels at given positions, issue #181.
 Drop the ‘type’ vertex attribute after bipartite projection, the projections are not bipartite any more, issue #255.
 Print logical attributes in header properly (i.e. encoded by
l
, notx
, which is for complex attributes. Issue #578.  Add a constructor for
communities
objects, seecreate.communities()
. Issue #547.  Better error handling in the GraphML parser.
 GraphML reader is a bit more lenient now; makes it possible to read GraphML files saved from yWorks apps.
 Fixed a bug in
constaint()
, issue #580.  Bipartite projection now detects invalid edges instead of giving a cryptic error, issue #543.
 Fixed the
simplify
argument ofgraph.formula()
, which was broken, issue #586.  The function
crossing()
adds better names to the result, fixes issue #587.  The
sir()
function gives an error if the input graph is not simple, fixes issue #582.  Calling igraph functions from igraph callbacks is not allowed now, fixes issue #571.
igraph 0.7.0
CRAN release: 20140205
February 4, 2014
Release Notes
There are a bunch of new features in the library itself, and other important changes in the life of the project. Thanks everyone for sending code and reporting bugs!
igraph @ github
igraph’s development has moved from Launchpad to github. This has actually happened several month ago, but never announced officially. The place for reporting bugs is at https://github.com/igraph/igraph/issues.
New homepage
igraph’s homepage is now hosted at http://igraph.org, and it is brand new. We wanted to make it easier to use and modern.
Better nightly downloads
You can download nightly builds from igraph at http://igraph.org/nightly. Source and binary R packages (for windows and OSX), are all built.
New features and bug fixes
 Added a demo for hierarchical random graphs, invoke it via
demo(hrg)
.  Make attribute prefixes optional when writing a GraphML file.
 Added function
mod.matrix()
.  Support edge weights in leading eigenvector community detection.
 Added the LAD library for checking (sub)graph isomorphism, version 1.
 Logical attributes.
 Added
layout.bipartite()
function, a simple twocolumn layout for bipartite graphs.  Support incidence matrices in bipartite Pajek files.
 Pajek files in matrix format are now directed by default, unless they are bipartite.
 Support weighted (and signed) networks in Pajek when file is in matrix format.
 Fixed a bug in
barabasi.game()
, algorithm psumtreemultiple just froze.  Function
layout.mds()
by default returns a layout matrix now.  Added support for Boolean attributes in the GraphML and GML readers and writer.
 Change MDS layout coordinates, first dim is according to first eigenvalue, etc.

plot.communities()
(plot.igraph()
, really) draws a border around the marked groups by default.  printing graphs now converts the
name
graph attribute to character  Convenience functions to query and set all attributes at once:
vertex.attriubutes()
,graph.attributes()
andedge.attributes()
.  Function
graph.disjoint.union()
handles attributes now.  Rewrite
graph.union()
to handle attributes properly. 
rewire()
: now supports the generation and destruction of loops.  ErdosRenyi type bipartite random graphs:
bipartite.random.game()
.  Support the new options (predecessors and inbound_edges) of
get_shortest_paths()
, reorganized the output ofget.shortest.paths()
completely.  Added
graphlets()
and related functions.  Fix modularity values of multilevel community if there are no merges at all.
 Fixed bug when deleting edges with FALSE in the matrix notation.
 Fix
bonpow()
andalpha.centrality()
and make sure that the sparse solver is called. 
tkplot()
news: enable setting coordinates from the command line viatkplot.setcoords()
and access to the canvas viatkplot.canvas()
.  Fixed a potential crash in
igraph_edge_connectivity()
, because of an uninitialized variable in the C code.  Avoiding overflow in
closeness()
and related functions.  Check for NAs after converting ‘type’ to logical in
bipartite.projection()
. 
graphNEL
conversion functions only load the ‘graph’ package if it was not loaded before and they load it at the end of the search path, to minimize conflicts.  Fixed a bug when creating graphs from adjacency matrices, we now convert them to double, in case they are integers.
 Fixed an invalid memory read (and a potential crash) in the infomap community detection.
 Fixed a memory leak in the functions with attribute combinations.
 Removed some memory leaks from the SCG functions.
 Fixed some memory leaks in the ray tracer.
 Fixed memory leak in
graph.bfs()
andgraph.dfs()
.  Fix a bug in triad census that set the first element of the result to NaN.
 Fixed a crash in
is.chordal()
.  Fixed a bug in weighted modularity calculation, sum of the weights was truncated to an integer.
 Fixed a bug in weighted multilevel communtiies, the maximum weight was rounded to an integer.
 Fixed a bug in
centralization.closeness.tmax()
.  Reimplement pushrelabel maximum flow with gap heuristics.
 Maximum flow functions now return some statistics about the push relabel algorithm steps.
 Function
arpack()
now gives error message if unknown options are given.  Fixed missing whitespace in Pajek writer when the ID attribute was numeric.
 Fixed a bug that caused the GML reader to crash when the ID attribute was nonnumeric.
 Fixed issue #500, potential segfault if the two graphs in BLISS differ in the number of vertices or edges.
 Added
igraphtest()
function.  Fix dyad census instability, sometimes incorrect results were reported.
 Dyad census detects integer overflow now and gives a warning.
 Function
add.edges()
does not allow now zeros in the vertex set.  Added a function to count the number of adjacent triangles:
adjacent.triangles()
.  Added
graph.eigen()
function, eigenproblems on adjacency matrices.  Added some workarounds for functions that create a lot of graphs,
decompose.graph()
andgraph.neighborhood()
use it. Fixes issue #508.  Added weights support for
optimal.community()
, closes #511.  Faster maximal clique finding.
 Added a function to count maximum cliques.
 Set operations: union, intersection, disjoint, union, difference, compose now work based on vertex names (if they are present) and keep attributes, closes #20.
 Removed functions
graph.intersection.by.name()
,graph.union.by.name()
,graph.difference.by.name()
.  The
+
operator on graphs now callsgraph.union()
if both argument graphs are named, and callsgraph.disjoint.union()
otherwise.  Added function
igraph.version()
.  Generate graphs from a stochastic block model:
sbm.game()
.  Do not suggest the stats, XML, jpeg and png packages any more.
 Fixed a
set.vertex/edge.attribute
bug that changed both graph objects, after copying (#533)  Fixed a bug in
barabasi.game
that caused crashes.  We use PRPACK to calculate PageRank scores see https://github.com/dgleich/prpack
 Added
'which
argument tobipartite.projection
(#307).  Add
normalized
argument to closeness functions, fixes issue #3.  R: better handling of complex attributes,
[[
on vertex/edge sets, fixes #231.  Implement the
start
argument inhrg.fit
(#225).  Set root vertex in ReingoldTilford layout, solves #473.
 Fix betweenness normalization for directed graphs.
 Fixed a bug in
graph.density
that resulted in incorrect values for undirected graphs with loops  Fixed a bug when many graphs were created in one C call (e.g. by
graph.decompose
), causing #550.  Fixed sparse
graph.adjacency
bugs for graphs with one edge, and graphs with zero edges.  Fixed a bug that made BellmanFord shortest paths calculations fail.
 Fixed a
graph.adjacency
bug for undirected, weighted graphs and sparse matrices. 
main
,sub
,xlab
andylab
are proper graphics parameters now (#555). 
graph.data.frame
coerces arguments to data frame (#557).  Fixed a minimum cut bug for weighted undirected graphs (#564).
 Functions for simulating epidemics (SIR model) on networks, see the
sir
function.  Fixed argument ordering in
graph.mincut
and related functions.  Avoid copying attributes in query functions and print (#573), these functions are much faster now for graphs with many vertices/edges and attributes.
 Speed up writing GML and GraphML files, if some attributes are integer. It was reallyreally slow.
 Fix multiple root vertices in
graph.bfs
(#575).
igraph 0.6.6
CRAN release: 20131028
Released Oct 28, 2013
Some bugs fixed:
 Fixed a potential crash in the infomap.community() function.
 Various fixed for the operators that work on vertex names (#136).
 Fixed an example in the arpack() manual page.
 arpack() now gives error message if unknown options are supplied (#492).
 Better arpack() error messages.
 Fixed missing whitespace in Pajek writer when ID attribute was numeric.
 Fixed dyad census instability, sometimes incorrect results were reported (#496).
 Fixed a bug that caused the GML reader to crash when the ID attribute was nonnumeric
 Fixed a potential segfault if the two graphs in BLISS differ in the number of vertices or edges (#500).
 Added the igraphtest() function to run tests from R (#485).
 Dyad census detects integer overflow now and gives a warning (#497).
 R: add.edges() does not allow now zeros in the vertex set (#503).
 Add C++ namespace to the files that didn’t have one. Fixes some incompatibility with other packages (e.g. rgl) and mysterious crashes (#523).
 Fixed a bug that caused a side effect in set.vertex.attributes(), set.edge.attributes() and set.graph.attributes() (#533).
 Fixed a bug in degree.distribution() and cluster.distribution() (#257).
igraph 0.6.52
CRAN release: 20130523
Released May 16, 2013
Worked two CRAN check problems, and a gfortran bug (string bound checking does not work if code is called from C and without string length arguments at the “right” place).
Otherwise identical to 0.6.51.
igraph 0.6.51
CRAN release: 20130228
Released February 27, 2013
Fixing an annoying bug, that broke two other packages on CRAN:
 Setting graph attributes failed sometimes, if the attributes were lists or other complex objects.
igraph 0.6.5
CRAN release: 20130225
Released February 24, 2013
This is a minor release, to fix some very annoying bugs in 0.6.4:
 igraph should now work well with older R versions.
 Eliminate gap between vertex and edge when plotting an edge without an arrow. Fixes #1118448.
 Fixed an outofbounds array indexing error in the DrL layout, that potentially caused crashes.
 Fixed a crash in weighted betweenness calculation.
 Plotting: fixed a bug that caused misplaced arrows at rectangle vertex shapes.
igraph 0.6.4
CRAN release: 20130204
Released February 2, 2013
The version number is not a mistake, we jump to 0.6.4 from 0.6, for technical reasons. This version was actually never really released, but some R packages of this version were uploaded to CRAN, so we include this version in this NEW file.
New features and bug fixes
Added a vertex shape API for defining new vertex shapes, and also a couple of new vertex shapes.
Added the get.data.frame() function, opposite of graph.data.frame().
Added bipartite support to the Pajek reader and writer, closes bug #1042298.
degree.sequence.game() has a new method now: “simple_no_multiple”.
Added the is.degree.sequence() and is.graphical.degree.sequence() functions.
rewire() has a new method: “loops”, that can create loop edges.
Walktrap community detection now handles isolates.
layout.mds() returns a layout matrix now.
layout.mds() uses LAPACK instead of ARPACK.
Handle the ‘~’ character in write.graph and read.graph. Bug #1066986.
Added k.regular.game().
Use vertex names to plot if no labels are specified in the function call or as vertex attributes. Fixes issue #1085431.
power.law.fit() can now use a C implementation.
Fixed a bug in barabasi.game() when out.seq was an empty vector.
Fixed a bug that made functions with a progress bar fail if called from another package.
Fixed a bug when creating graphs from a weighted integer adjacency matrix via graph.adjacency(). Bug #1019624.
Fixed overflow issues in centralization calculations.
Fixed a minimal.st.separators() bug, some vertex sets were incorrectly reported as separators. Bug #1033045.
Fixed a bug that mishandled vertex colors in VF2 isomorphism functions. Bug #1032819.
Pajek exporter now always quotes strings, thanks to Elena Tea Russo.
Fixed a bug with handling small edge weights in shortest paths calculation in shortest.paths() (Dijkstra’s algorithm.) Thanks to Martin J Reed.
Weighted transitivity uses V(graph) as ‘vids’ if it is NULL.
Fixed a bug when ‘pie’ vertices were drawn together with other vertex shapes.
Speed up printing graphs.
Speed up attribute queries and other basic operations, by avoiding copying of the graph. Bug #1043616.
Fixed a bug in the NCV setting for ARPACK functions. It cannot be bigger than the matrix size.
layout.merge()’s DLA mode has better defaults now.
Fixed a bug in layout.mds() that resulted vertices on top of each other.
Fixed a bug in layout.spring(), it was not working properly.
Fixed layout.svd(), which was completely defunct.
Fixed a bug in layout.graphopt() that caused warnings and on some platforms crashes.
Fixed community.to.membership(). Bug #1022850.
Fixed a graph.incidence() crash if it was called with a nonmatrix argument.
Fixed a get.shortest.paths bug, when output was set to “both”.
Motif finding functions return NA for isomorphism classes that are not motifs (i.e. not connected). Fixes bug #1050859.
Fixed get.adjacency() when attr is given, and the attribute has some complex type. Bug #1025799.
Fixed attribute name in graph.adjacency() for dense matrices. Bug #1066952.
Fixed erratic behavior of alpha.centrality().
Fixed igraph indexing, when attr is given. Bug #1073705.
Fixed a bug when calculating the largest cliques of a directed graph. Bug #1073800.
Fixed a bug in the maximal clique search, closes #1074402.
Warn for negative weights when calculating PageRank.
Fixed dense, unweighted graph.adjacency when diag=FALSE. Closes issue #1077425.
Fixed a bug in eccentricity() and radius(), the results were often simply wrong.
Fixed a bug in get.all.shortest.paths() when some edges had zero weight.
graph.data.frame() is more careful when vertex names are numbers, to avoid their scientific notation. Fixes issue #1082221.
Better check for NAs in vertex names. Fixes issue #1087215
Fixed a potential crash in the DrL layout generator.
Fixed a bug in the ReingoldTilford layout when the graph is directed and mode != ALL.
igraph 0.6
CRAN release: 20120614
Released June 11, 2012
See also the release notes at http://igraph.sf.net/relnotes0.6.html
R: Major new features
 Vertices and edges are numbered from 1 instead of 0. Note that this makes most of the old R igraph code incompatible with igraph 0.6. If you want to use your old code, please use the igraph0 package. See more at http://igraph.sf.net/relnotes0.6.html.
 The ‘[’ and ‘[[’ operators can now be used on igraph graphs, for ‘[’ the graph behaves as an adjacency matrix, for ‘[[’ is is treated as an adjacency list. It is also much simpler to manipulate the graph structure, i.e. add/remove edges and vertices, with some new operators. See more at ?graph.structure.
 In all functions that take a vector or list of vertices or edges, vertex/edge names can be given instead of the numeric ids.
 New package ‘igraphdata’, contains a number of data sets that can be used directly in igraph.
 Igraph now supports loading graphs from the Nexus online data repository, see nexus.get(), nexus.info(), nexus.list() and nexus.search().
 All the community structure finding algorithm return a ‘communities’ object now, which has a bunch of useful operations, see ?communities for details.
 Vertex and edge attributes are handled much better now. They are kept whenever possible, and can be combined via a flexible API. See ?attribute.combination.
 R now prints igraph graphs to the screen in a more structured and informative way. The output of summary() was also updated accordingly.
R: Other new features
 It is possible to mark vertex groups on plots, via shading. Communities and cohesive blocks are plotted using this by default.
 Some igraph demos are now available, see a list via ‘demo(package=“igraph”)’.
 igraph now tries to select the optimal layout algorithm, when plotting a graph.
 Added a simple console, using Tcl/Tk. It contains a text area for status messages and also a status bar. See igraph.console().
 Reimplemented igraph options support, see igraph.options() and getIgraphOpt().
 Igraph functions can now print status messages.
R: New or updated functions
Community detection
 The multilevel modularity optimization community structure detection algorithm by Blondel et al. was added, see multilevel.community().
 Distance between two community structures: compare.communities().
 Community structure via exact modularity optimization, optimal.community().
 Hierarchical random graphs and community finding, porting the code from Aaron Clauset. See hrg.game(), hrg.fit(), etc.
 Added the InfoMAP community finding method, thanks to Emmanuel Navarro for the code. See infomap.community().
Shortest paths
 Eccentricity (eccentricity()), and radius (radius()) calculations.
 Shortest path calculations with get.shortest.paths() can now return the edges along the shortest paths.
 get.all.shortest.paths() now supports edge weights.
Centrality
 Centralization scores for degree, closeness, betweenness and eigenvector centrality. See centralization.scores().
 Personalized PageRank scores, see page.rank().
 Subgraph centrality, subgraph.centrality().
 Authority (authority.score()) and hub (hub.score()) scores support edge weights now.
 Support edge weights in betweenness and closeness calculations.
 bonpow(), Bonacich’s power centrality and alpha.centrality(), Alpha centrality calculations now use sparse matrices by default.
 Eigenvector centrality calculation, evcent() now works for directed graphs.
 Betweenness calculation can now use arbitrarily large integers, this is required for some latticelike graphs to avoid overflow.
Input/output and file formats
 Support the DL file format in graph.read(). See http://www.analytictech.com/networks/dataentry.htm.
 Support writing the LEDA file format in write.graph().
Plotting and layouts
 Star layout: layout.star().
 Layout based on multidimensional scaling, layout.mds().
 New layouts layout.grid() and layout.grid.3d().
 Sugiyama layout algorithm for layered directed acyclic graphs, layout.sugiyama().
Graph generators
 New graph generators: static.fitness.game(), static.power.law.game().
 barabasi.game() was rewritten and it supports three algorithms now, the default algorithm does not generate multiple or loop edges. The graph generation process can now start from a supplied graph.
 The WattsStrogatz graph generator, igraph_watts_strogatz() can now create graphs without loop edges.
Others
 Added the Spectral Coarse Graining algorithm, see scg().
 The cohesive.blocks() function was rewritten in C, it is much faster now. It has a nicer API, too. See demo(“cohesive”).
 Added generic breadthfirst and depthfirst search implementations with many callbacks, graph.bfs() and graph_dfs().
 Support vertex and edge coloring in the VF2 (sub)graph isomorphism functions (graph.isomorphic.vf2(), graph.count.isomorphisms.vf2(), graph.get.isomorphisms.vf2(), graph.subisomorphic.vf2(), graph.count.subisomorphisms.vf2(), graph.get.subisomorphisms.vf2()).
 Assortativity coefficient, assortativity(), assortativity.nominal() and assortativity.degree().
 Vertex operators that work by vertex names: graph.intersection.by.name(), graph.union.by.name(), graph.difference.by.name(). Thanks to Magnus Torfason for contributing his code!
 Function to calculate a noninduced subgraph: subgraph.edges().
 More comprehensive maximum flow and minimum cut calculation, see functions graph.maxflow(), graph.mincut(), stCuts(), stMincuts().
 Check whether a directed graph is a DAG, is.dag().
 has.multiple() to decide whether a graph has multiple edges.
 Added a function to calculate a diversity score for the vertices, graph.diversity().
 Graph Laplacian calculation (graph.laplacian()) supports edge weights now.
 Biconnected component calculation, biconnected.components() now returns the components themselves.
 bipartite.projection() calculates multiplicity of edges.
 Maximum cardinality search: maximum.cardinality.search() and chordality test: is.chordal()
 Convex hull computation, convex.hull().
 Contract vertices, contract.vertices().
igraph 0.5.3
CRAN release: 20091122
Released November 22, 2009
Bugs corrected in the R interface
 Some small changes to make ‘R CMD check’ clean
 Fixed a bug in graph.incidence, the ‘directed’ and ‘mode’ arguments were not handled correctly
 Betweenness and edge betweenness functions work for graphs with many shortest paths now (up to the limit of long long int)
 When compiling the package, the configure script fails if there is no C compiler available
 igraph.from.graphNEL creates the right number of loop edges now
 Fixed a bug in bipartite.projection() that caused occasional crashes on some systems
igraph 0.5.2
CRAN release: 20090414
Released April 10, 2009
See also the release notes at http://igraph.sf.net/relnotes0.5.2.html
New in the R interface
 Added progress bar support to beweenness() and betweenness.estimate(), layout.drl()
 Speeded up betweenness estimation
 Speeded up are.connected()
 Johnson’s shortest paths algorithm added
 shortest.paths() has now an ‘algorithm’ argument to choose from the various implementations manually
 Always quote symbolic vertex names when printing graphs or edges
 Average nearest neighbor degree calculation, graph.knn()
 Weighted degree (also called strength) calculation, graph.strength()
 Some new functions to support bipartite graphs: graph.bipartite(), is.bipartite(), get.incidence(), graph.incidence(), bipartite.projection(), bipartite.projection.size()
 Support for plotting curved edges with plot.igraph() and tkplot()
 Added support for weighted graphs in alpha.centrality()
 Added the label propagation community detection algorithm by Raghavan et al., label.propagation.community()
 cohesive.blocks() now has a ‘cutsetHeuristic’ argument to choose between two cutset algorithms
 Added a function to “unfold” a tree, unfold.tree()
 New tkplot() arguments to change the drawing area
 Added a minimal GUI, invoke it with tkigraph()
 The DrL layout generator, layout.drl() has a three dimensional mode now.
Bugs corrected in the R interface
 Fixed a bug in VF2 graph isomorphism functions
 Fixed a bug when a sparse adjacency matrix was requested in get.adjacency() and the graph was named
 VL graph generator in degree.sequence.game() checks now that the sum of the degrees is even
 Many fixes for supporting various compilers, e.g. GCC 4.4 and Sun’s C compiler
 Fixed memory leaks in graph.automorphisms(), BellmanFord shortest.paths(), independent.vertex.sets()
 Fix a bug when a graph was imported from LGL and exported to NCOL format (#289596)
 cohesive.blocks() creates its temporary file in the session temporary directory
 write.graph() and read.graph() now give error messages when unknown arguments are given
 The GraphML reader checks the name of the attributes to avoid adding a duplicate ‘id’ attribute
 It is possible to change the ‘ncv’ ARPACK parameter for leading.eigenvector.community()
 Fixed a bug in path.length.hist(), ‘unconnected’ was wrong for unconnected and undirected graphs
 Better handling of attribute assingment via iterators, this is now also clarified in the manual
 Better error messages for unknown vertex shapes
 Make R package unload cleanly if unloadNamespace() is used
 Fixed a bug in plotting square shaped vertices (#325244)
 Fixed a bug in graph.adjacency() when the matrix is a sparse matrix of class “dgTMatrix”
igraph 0.5.1
CRAN release: 20080712
Released July 14, 2008
See also the release notes at http://igraph.sf.net/relnotes0.5.1.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 BelmannFord algorithm.
 Shortest path functions return ‘Inf’ for unreachable vertices.
 New function ‘is.mutual’ to find mutual edges in a directed graph.
 Added inverse logweighted 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 ReingoldTilford 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 (34 vertices) graphs.
 Corrected the random sampling implementation (igraph_random_sample), now it always generates unique numbers. This affects the Gnm ErdosRenyi 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 nonsymmetric 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 endofline 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
igraph 0.5
CRAN release: 20080213
Released February 14, 2008
See also the release notes at http://igraph.sf.net/relnotes0.5.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 FruchtermanReingold 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 ( , ,
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
igraph 0.4.5
CRAN release: 20071222
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):125  Biconnected components and articulation points.  R interface: better printing of attributes.  R interface: graph attributes can be used via ‘$’.
Bug fixed:  ErdosRenyi random graph generators rewritten.
igraph 0.4.4
CRAN release: 20071003
Released October 3, 2007
This release should work seamlessly with the new R 2.6.0 version. Some other bugs were also fixed:  A bug was fixed in the ErdosRenyi graph generator, which sometimes added an extra vertex.
igraph 0.4.3
CRAN release: 20070809
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.  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.
igraph 0.4.2
CRAN release: 20070606
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 ReingoldTilford 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
CRAN release: 20070523
Released May 23, 2007
This is a minor release, it corrects a number of bugs, mostly in the R package.
igraph 0.4
CRAN release: 20070521
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 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
is.loop and is.multiple were added
topological sorting
VF2 isomorphism algorithm
support for reading graphs from the Graph Database for isomorphism
graph.mincut can 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
functions for creating dendrograms 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
igraph 0.3.2
CRAN release: 20061214
Released Dec 19, 2006
This is a new major release, it contains many new things:
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 selfloop 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
 spinglassbased 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 ErdosRenyi graph generation corrected: it had problems with generating large directed graphs
 bug in constraint calculation corrected, it works well now
 fixed memory leaks in the GraphML reader
 error handling bug corrected in the GraphML reader
 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
CRAN release: 20060824
Released Aug 23, 2006
This is a bugfix release. Bugs fixed:  reciprocity corrected to avoid segfaults  some docs updates  various R package updates to make it conform to the CRAN rules
igraph 0.2
CRAN release: 20060823
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)  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 specifically 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.