Comment 1 for bug 1082221

Thanks for your report!

I think this happens, if the symbolic names are not of type character for one argument and character for the other. E.g.

library(igraph)
verts <- data.frame(id=c("1001", "100000", "200000"))
dat <- data.frame(from=c(1001, 100000, 200000), to=c(100000, 200000, 100000))
g <- graph.data.frame(dat, vertices=verts)

An easy workaround is to convert everything to character. But I'll add the options(scipen) to graph.data.frame anyway.