CODEWITHSUNDEEP
rigraph
timothyjgraham
timothyjgraham

Reputation: 1232

How to remove outgoing edges from all vertices not equal to "x"

I have a directed graph 'g' with 115 nodes and 1098 edges. It is a hyperlink graph (i.e. nodes are websites and edges represent existence of a hyperlink).

I want to remove all the outbound edges from all vertices that are not from a particular node of interest (id=7). I am trying to create a graph representing only the outlinks from a particular website (i.e. which websites it links to).

I have tried various attempts at using the delete.edges function, but I am very confused about how to achieve this.

I have also tried: 

g[1:6,] <- FALSE

followed by:

g[8:1098,] <- FALSE

But this doesn't work either.

Upvotes: 0

Views: 327

Answers (1)

Gabor Csardi
Gabor Csardi

Reputation: 10825

I am not sure why your code does not work, it would be great to have a reproducible example, with data. I suspect that your graph has vertex names and you are mixing up the vertex names and the numeric vertex ids. Anyway, the simplest way is probably:

library(igraph)
links <- cbind(from=c( 2, 3, 7, 7, 7),
                 to=c(10,11,12,13,14))
g <- graph.edgelist(links)

str(g)
# IGRAPH D--- 14 5 -- 
# + edges:
# [1] 2->10 3->11 7->12 7->13 7->14

g[-7,] <- FALSE

str(g)
# IGRAPH D--- 14 3 -- 
# + edges:
# [1] 7->12 7->13 7->14

Upvotes: 1

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