CODEWITHSUNDEEP
rsizeigraphedges
Benoît
Benoît

Reputation: 1

Change edge size in igraph

I want to plot a simple star graph in which the size of the edges depends on a score representing a difference of perception between the central node (e.g.,a leader) and the other nodes (e.g., its employees).

I succeeded in modifying the colors, the size of the node, the width of the edges but not the size of the latter.

How would you do?

library(igraph)
nodes <- read.csv("exemple_nodes.csv", header=T, as.is=T)
links <- read.csv("exemple_edges.csv", header=T, as.is=T)
st <- graph_from_data_frame(d=links, vertices=nodes, directed=T)
plot(st, vertex.color=V(st)$perception.type)

Upvotes: 0

Views: 699

Answers (2)

G5W
G5W

Reputation: 37641

I think that what you want is to position the vertices so that you can control the length of the edges. If that is not what you want, then please explain what you mean by the "size" of the edges.

You do not provide your data so that we cannot use exactly your graph. I will use a generic star graph as an example. In order to control the placement of the vertices, you need to use the layout parameter. The basic function layout_as_star will place the first vertex at the center and the other vertices equally spaced around it at the same distance. Because this layout function places the center vertex at (0,0) and the remaining nodes on a unit circle around the center, it is easy to adjust it so that the distance of the outer vertices is controlled by a parameter. Just multiply the coordinates by the parameter and it will proportionally change the distance. I just make something up for the distances, but you can use your parameter.

## Make up perception parameter
set.seed(271828)
Perception = sample(4, 9, replace=T)
Perception
[1] 2 3 4 4 1 4 2 2 1

Now there is one weight for every outer vertex, but we need a weight for the central vertex. We don't want it to move so we use a weight of 1.

Weight = c(1, Perception)
LO = layout_as_star(S10)
LO = LO*Weight
plot(S10, layout=LO)

Graph with weighted edges

Upvotes: 1

Cl&#233;ment LVD
Cl&#233;ment LVD

Reputation: 702

With the ggraph package and one of the geom_edge_ func' (e.g., geom_edge_arc, geom_edge_diagonal), in order to use the edge_width parameter, depending on a numeric value associated with the edges, in the edges-list (hereafter "value"). For example:

  ggraph::ggraph(st) +
  
    ggraph::geom_edge_diagonal(aes(edge_width = as.numeric(value)) )

In addition, ggraph allow you to specify other edges-parameters inside the geom_edge_ func', for example edge_alpha = as.numeric(value).

Upvotes: 1

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