[igraph] Character Vectors Containing Vertex Names

[Lorenzo Isella]

Dear All,
I have just updated my igraph installation.
When I looked at the news in the R interface, I read the following

> All functions that have vertex id input parameters, handle character vectors 
> containing vertex names now.

I remember (though I cannot find the precise email) that this was 
anticipated some months ago in a reply to an email of mine on this very 
mailing list.
In particular, I wonder if this could be useful to simplify a bit the 
procedure I follow when translating an edge list stored into a text 
file, where every node is given by a symbolic ID (just a number in this 
case, but it could be something else) into an igraph graph.

To fix the ideas, see the code snippet below followed by the 
corresponding input file.
Any thoughts are appreciated.
Cheers

Lorenzo


########################################################

library(igraph)
library(Cairo)


tab <- read.table("my_net.dat", header=FALSE)



g <- graph.data.frame(tab, dir=FALSE) #create graph where the numbers 
providing the visitor ID are

g <- simplify(g)

d <- get.diameter(g,weights=NA)




l <- layout.fruchterman.reingold(g)

l <- layout.norm(l, -1,1, -1,1)


CairoPDF("large_network.pdf")

plot(g, layout=l,
     vertex.label.dist=0.5,   vertex.color="#ff000033",
     vertex.frame.color="#ff000033", 
edge.color="#55555533",vertex.label=NA, vertex.size=4
     #, main=week[sel_day]
#as.expression(c(sprintf("Power = %.3f", power))) ,cex=1.2)
     #,ylab=as.expression(c(sprintf("Week %1d",k)))
     )



V(g)$id <- seq(vcount(g))-1
g2 <- subgraph(g, d)


plot(g2, layout=l[ V(g2)$id+1, ],
vertex.color="blue", vertex.frame.color="blue",
   edge.color="blue",vertex.label=NA, edge.width=2, vertex.size=4,
   add=TRUE, rescale=FALSE)



dev.off()


##################################


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