R: largest.cliques bug when graph is directed

[Gábor Csárdi]

Christos Hatzis <christos.hatzis@***> reported this:

There is a problem with the largest clique computation in the recent version
of igraph.

library(igraph)
adj <- matrix(1, nrow=11, ncol=11) - diag(11)
g <- graph.adjacency(adj)
largest.cliques(g)
# [[1]]
# [1] 10 8 1
#
# [[2]]
# [1] 9 7 1
#
# [[3]]
# [1] 8 7 1
#
# Warning message:
# In largest.cliques(g) :
# At cliques.c:958 :directionality of edges is ignored for directed graphs

>> sessionInfo()
> R version 2.15.2 (2012-10-26)
> Platform: x86_64-w64-mingw32/x64 (64-bit)
>
> locale:
> [1] LC_COLLATE=English_United States.1252 LC_CTYPE=English_United
> States.1252
> [3] LC_MONETARY=English_United States.1252 LC_NUMERIC=C
>
> [5] LC_TIME=English_United States.1252
>
> attached base packages:
> [1] stats graphics grDevices utils datasets methods base
>
> other attached packages:
> [1] igraph_0.6-3
>
> ----------------------------------------------------------
>
> An older version of igraph gave the correct answer
>
>> library(igraph)
>> adj <- matrix(1, nrow=11, ncol=11) - diag(11)
>> g <- graph.adjacency(adj)
>> largest.cliques(g)
> [[1]]
> [1] 0 1 2 3 4 5 6 7 8 9 10
>
> Warning message:
> In largest.cliques(g) :
> At cliques.c:801 :directionality of edges is ignored for directed graphs
>
>> sessionInfo()
> R version 2.12.2 (2011-02-25)
> Platform: x86_64-pc-mingw32/x64 (64-bit)
>
> locale:
> [1] LC_COLLATE=English_United States.1252 LC_CTYPE=English_United
> States.1252
> [3] LC_MONETARY=English_United States.1252 LC_NUMERIC=C
>
> [5] LC_TIME=English_United States.1252
>
> attached base packages:
> [1] stats graphics grDevices utils datasets methods base
>
> other attached packages:
> [1] igraph_0.5.5-3

[Gábor Csárdi (gabor.csardi)]

Fixed in revisions #2992 (0.6-main) and #3036 (0.7-main).

[Gábor Csárdi (gabor.csardi)]

Although it might be worth checking the other clique finding functions as well.....

[Gábor Csárdi (gabor.csardi)]

The development of igraph has moved to github, so please do not comment on this bug here. You are of course welcome to comment on github, here:
https://github.com/igraph/igraph/issues/122