CODEWITHSUNDEEP
rigraph
user2030503
user2030503

Reputation: 3114

Union of igraph objects loses attributes

I have two igraph objects, which have different color attributes. Vertices "A" and "B" in first graph are colored red. Vertices "AA" and "BB" in second graph are colored green. After joining the two, the different colors are lost.

library(igraph)

graph.1= graph.data.frame(data.frame(start=c("a", "b"), end=c("A", "B")))
V(graph.1)[name%in% c("A", "B")]$color= "red"

graph.2= graph.data.frame(data.frame(start=c("a", "b"), end=c("AA", "BB")))
V(graph.2)[name%in% c("AA", "BB")]$color= "green"

graph= graph.union.by.name(graph.1, graph.2)

plot(graph)

enter image description here

How can I preserve the distinct colors when joining ?

Upvotes: 2

Views: 1225

Answers (1)

jlhoward
jlhoward

Reputation: 59415

igraph doesn't loose the colors, it stores them in $color_1 and $color_2. I think this is because in the general case there might be common vertices with different colors. What would you do then?

Try this:

V(graph)$color <- ifelse(is.na(V(graph)$color_1),
                         V(graph)$color_2,V(graph)$color_1)
plot(graph)

BTW: your code didn't run for me. I had to use:

graph <- graph.union(graph.1, graph.2, byname=T)

Upvotes: 5

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