[R] possible bug with largest.cliques in igraph_0.6-3

[Christos Hatzis]

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

	
Thanks.

Christos Hatzis, Ph.D.
Nuvera Biosciences, Inc.
999 Broadway, Suite 301
Saugus, MA 01906