Visualisation iGraph and label alignment

Question

The code

library(igraph)

g <- graph.tree(n = 2 ^ 3 - 1, children = 2)
node_labels <- c("", "Group A", "Group B", "(1)Text", "(2)I am a longer text", "(3)I am a long long long text", "(4)X")
lay = layout.reingold.tilford(g)  

plot(g,
     vertex.size = 4,                  # node size
     vertex.color = '#C4D8E2',          # node color
     vertex.label = node_labels,        # node labels
     vertex.label.dist = 5,             # node label size
     vertex.label.font = 2,             # node label type (bold)
     vertex.label.degree=0.0,
     margin=c(0,0,0,0),
     layout=-lay[, 2:1]
)

gives me a graph with labels. How can align the labels 1 .. 4, that they are left aligned, right beside the circle and not center aligned? No 3 is correct from my point of view. Switching to ggraph would be an alternative, but here rotating of labels did not work.

score 1 · Answer 1 · answered Jul 01 '18 at 11:23

Here the code with the calculation:

library(igraph)

g <- graph.tree(n = 2 ^ 3 - 1, children = 2)
node_labels <- c("", "Group A", "Group B", "(1)Text", "(2)I am a longer text", "(3)I am a long long long text", "(4)X")
lay = layout.reingold.tilford(g)  

t1 <- sapply(as.vector( node_labels), FUN = strwidth,units='in')
t2 <- (t1 - min(t1))/ (max(t1) - min(t1))*3+0.9


plot(g,
     vertex.size = 4,                  # node size
     vertex.color = '#C4D8E2',          # node color
     vertex.label = node_labels,        # node labels
     vertex.label.dist = t2,             # node label size
     vertex.label.font = 2,             # node label type (bold)
     vertex.label.degree=0.0,
     margin=c(0,0,0,0),
     layout=-lay[, 2:1]
)

It is a littlbe bit better, but I can't do it perfectly.

score 0 · Answer 2 · answered Jun 29 '18 at 14:13

0

If you can manually change the distance for each label like below -

plot(g,
     vertex.size = 4,                  
     vertex.color = '#C4D8E2',          
     vertex.label = node_labels,        
     vertex.label.dist = c(0,0,0,0,8,12,0), # vector of distance
     vertex.label.font = 2,            
     vertex.label.degree=0.0,
     margin=c(0,0,0,0),
     layout=-lay[, 2:1]
)

Or you might want to have a function created to get those length from each vertex. This I am leaving on you to improvise.

t1 <- sapply(node_labels, FUN = nchar)
t2 <- (t1 - min(t1))/ (max(t1) - min(t1))
t2 <- t2*12


plot(g,
     vertex.size = 4,                  
     vertex.color = '#C4D8E2',          
     vertex.label = node_labels,        
     vertex.label.dist = t2, # vector of distance
     vertex.label.font = 2,            
     vertex.label.degree=0.0,
     margin=c(0,0,0,0),
     layout=-lay[, 2:1]
)

answered Jun 29 '18 at 14:13

Vikash Kumar

348
1
9

Hi Vikash, I will go for the function, but I think this will be depend on the font that is used. I have to find something for determining the length of the strings. – xyx Jun 29 '18 at 15:37
True, depends on font. Font will be global for all labels. You can consider using alternative solution which I have provided where I count the characters and use to get vector of distance. You can change multiplication -> t2*12 by either increasing t2*15 or decrease t2*6. Hope this helps! – Vikash Kumar Jun 30 '18 at 07:07
That is really weird. I do not get it to work. I tried to calculate the width of the string, but it do not work perfecty. – xyx Jul 01 '18 at 11:21

Visualisation iGraph and label alignment

2 Answers2