[igraph] changing vertex shape according to vertex characteristics

[Meenakshi Parameshwaran]

Dear all,

I am new to igraph and to R. I have a simple problem I hope you can help with. i am trying to visualise a classroom network and I want the vertices to have different colours by ethnic minority/majority background, and different shapes by gender. The colours work ok, but I can't make the shapes change.

#set color of vertex attribute according to ethmin

V(graph1)$color <- ifelse(ethmin4 == 1, "red", "blue")

V(graph1)$color

#set shape of vertex attribute according to gender

V(graph1)$shape <- ifelse(female4 == 1, "circle", "square")

V(graph1)$shape

myLayout <- layout.fruchterman.reingold(graph1)

plot.igraph(graph1,

            vertex.color = V(graph1)$color,

            vertex.shape = V(graph1)$shape,

            vertex.size = 15,

            edge.color = "black",

            edge.arrow.size = 0.05,

            layout = myLayout

)

But this doesn't work, and I get the following error:

Error in igraph.check.shapes(params("vertex", "shape")) : 

  Bad vertex shape(s): NA.

When I type V(graph1)$shape, I get the following so I think that has loaded correctly. And I think my shape names are correct.

 [1] "square" "circle" "square" "square" "circle" "square" "circle" "square" "circle" "square"

[11] "circle" "circle" "square" "square" "circle" "circle" "circle" NA       "square" "circle"

[21] "square"

Any ideas?

Thanks very much,

Meena

[Tamás Nepusz]

> #set shape of vertex attribute according to gender
> V(graph1)$shape <- ifelse(female4 == 1, "circle", "square")

If you have an NA value somewhere in the female4 vector, this will introduce NA values in the shape vector as well. E.g.:

> female4 <- c(1, 0, NA)

> ifelse(female4 == 1, "circle", "square")

[1] "circle" "square" NA

So, the solution is to get rid of the NA values from your female4 vector.

--
T.
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[Meenakshi Parameshwaran]

Dear Tamas,

Thanks for your advice here. I had NA values in my ethmin4 vector as well, but this did not seem to affect the colouring of the vertices. But I guess it affects the shapes. So I will try this and see.

Many thanks,

Meena

[Tamás Nepusz]

> Thanks for your advice here. I had NA values in my ethmin4 vector as well, but this did not seem to affect the colouring of the vertices. But I guess it affects the shapes. So I will try this and see.

Maybe the colors are not affected because igraph manages to interpret "NA" as a color; I don't know the details but maybe it is interpreted as "no fill color". However, there is no similar interpretation for "NA" as a shape.

--
Tamas