Saving a graph in Pajek with color attributes

[Richard O. Legendi]

I tried to save a simple graph in Pajek format with defined color values, but I get the following error message:

    > g <- graph.ring(10)
    > V(g)$color <- "red"
    > write.graph(g, format="pajek", file="C:\\tmp\\test.net")
    Error in write.graph.pajek(graph, file, ...) :
      At rinterface.c:761 : No such attribute, Invalid value
    Error during wrapup:
    >

I found the list archives, and found some hints to update to the most recent version of igraph. I've just updated to igraph_0.5.5-3 rj_0.5.5-4, but still no change.

I've also tried some alternatives like using set.vertex.attribute and ' and ` characters to define the color values, but wasn't able to make it work.

Based on the documentation I found in ?read.graph, there are two tables stating that the color values should work (if I got it right).

My sessionInfo() output:

> sessionInfo()
R version 2.12.1 (2010-12-16)
Platform: x86_64-pc-mingw32/x64 (64-bit)

locale:
[1] LC_COLLATE=Hungarian_Hungary.1250 LC_CTYPE=Hungarian_Hungary.1250
[3] LC_MONETARY=Hungarian_Hungary.1250 LC_NUMERIC=C
[5] LC_TIME=Hungarian_Hungary.1250

attached base packages:
[1] stats graphics grDevices utils datasets methods base

other attached packages:
[1] igraph_0.5.5-3 rj_0.5.5-4

loaded via a namespace (and not attached):
[1] tools_2.12.1

Tamás Nepusz pointed out at the igraph mailing list that I may have stumbled upon a bug, because the code is even worse on Mac OS X:

> library(igraph)
g <> g <- graph.ring(10)
> V(g)$color <- "red"
> V(g)$color
 [1] "red" "red" "red" "red" "red" "red" "red" "red" "red" "red"
> write.graph(g, format="pajek", file="test.net")
 *** caught segfault ***
address 0x8, cause 'memory not mapped'

Traceback:
 1: .Call("R_igraph_write_graph_pajek", graph, file, PACKAGE = "igraph")
 2: write.graph.pajek(graph, file, ...)
 3: write.graph(g, format = "pajek", file = "test.net")

He said that this is 0.6 (not 0.5.x), and it looks like the bug has been around for a while.

[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/446