Vertex labels: positions depend on length

[satuhelske]

Could you add an argument to plot.igraph such that the user could decide to align the vertex labels and/or fix the distances from the labels to the corresponding vertices in vertical or horizontal direction? At the moment the vertex label positions vary according to the length of the label, but if the vertices are aligned, it would be nice to have the labels aligned as well. Thank you for a great package!

[satuhelske]

I'm again inquiring about the possibility to change label positions. For personal use the problem is of course easy to solve by modifying the plot.igraph function (by deleting log10(nchar(labels) + 1)). However, I use the igraph package for drawing graphs in my own package which I would like to add to CRAN. It would be much easier to be able to use the original igraph functions instead of using my own copy of the plot.igraph function and all internal functions used by it – I've understood that using the ::: operator is not allowed in packages available in CRAN.

Below is an example of the problem. In the first graph the vertex labels are of the same length and align nicely.

adjm <- matrix(c(0,1,0,1,
                 0,0,1,1,
                 0,0,0,1,
                 0,0,0,0), nrow=4, byrow=TRUE)

g1 <- graph.adjacency(adjm, mode="directed")

values <- lapply(1:4, function(x) sample(1:4,4))

plot(g1, layout=layout.grid(g1, width=4), 
     vertex.shape="pie", vertex.pie=values,
     vertex.pie.color=list(heat.colors(4)),
     edge.curved=TRUE,
     vertex.label=LETTERS[1:4], vertex.size=50,
     vertex.label.dist=5, vertex.label.degree=pi/2, 
     edge.label=1:5, rescale=FALSE, 
     xlim=c(-0.2,3.5), ylim=c(0,0.5))

In the second graph the labels are of different lengths. The requested distance is the same for all vertex labels, but the true distances vary, which does not look good.

plot(g1, layout=layout.grid(g1, width=4), 
     vertex.shape="pie", vertex.pie=values,
     vertex.pie.color=list(heat.colors(4)),
     edge.curved=TRUE,
     vertex.label=c("A", "AA", "AAAA", "AAAAAA"), vertex.size=50,
     vertex.label.dist=5, vertex.label.degree=pi/2, 
     edge.label=1:5, rescale=FALSE, 
     xlim=c(-0.2,3.5), ylim=c(0,0.5))

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