wake_wake - 1 year ago 115
R Question

# igraph in R, how to select edges based on incident vertex attributes?

I am looking for a way to subgraph edges based on a vertex attribute score of at least one of the vertices that are incident on that edge.

Is there an easy way to do so?

Any suggestions?

This question is missing a reproducible example or any example data of any kind. I'm going to take a risk and answer based on what I can guess Is being asked. First, I'll create a sample graph and assign arbitrary "prop" values to each vertex. I'll color them assuming i'm interested in `prop>=3` and plot them.

``````library(igraph)

gg <- graph.atlas(711)
V(gg)\$name <- 1:7
V(gg)\$prop <- c(1,2,2,3,3,1,1)
V(gg)\$color <- ifelse(V(gg)\$prop>=3, "orange","yellow")
plot(gg)
``````

Now, I can find all the edges connected to a vertex with `prop>=3` with

``````E(gg)[inc(V(gg)[prop>=3])]
# Edge sequence:
#
# [3]  4 -- 3
# [4]  5 -- 4
# [5]  6 -- 5
# [10] 5 -- 3
``````

And if I like I can extract those to a sub-graph with

``````g2 <- subgraph.edges(gg, E(gg)[inc(V(gg)[prop>=3])])
plot(g2)
``````

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