Change edge thickness according to a column of a dataframe containing relations between actors

user_1306892 0
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This code plots a graph from dataframes of actors and relations.

library(igraph)
actors <- data.frame(name=c("Alice", "Bob", "Cecil", "David",
                            "Esmeralda"))
relations <- data.frame(from=c("Bob", "Cecil", "Cecil", "David",
                               "David", "Esmeralda"),
                        to=c("Alice", "Bob", "Alice", "Alice", "Bob", "Alice"),
                        friendship=c(4,15,5,2,11,1))
g <- graph_from_data_frame(relations, directed=TRUE, vertices=actors)

plot(g)

The result is:

enter image description here

I would like to change the thickness (not the length) of the arcs based on the value of relations$friendship.

igraph plot r
2 Answers

Try

plot(g,edge.width = E(g)$friendship, edge.arrow.size = E(g)$friendship)

enter image description here

Note that, the first value of E(g)$friendship is assigned to edge.arrow.size, instead of a vector. Maybe the improved feature will be added to future igraph version.

arrow.size The size of the arrows. Currently this is a constant, so it is the same for every edge. If a vector is submitted then only the first element is used, ie. if this is taken from an edge attribute then only the attribute of the first edge is used for all arrows. This will likely change in the future.

The default value is 1.

arrow.width The width of the arrows. Currently this is a constant, so it is the same for every edge. If a vector is submitted then only the first element is used, ie. if this is taken from an edge attribute then only the attribute of the first edge is used for all arrows. This will likely change in the future.

This argument is currently only used by plot.igraph.

The default value is 1, which gives the same width as before this option appeared in igraph.

user_121587570

This can be achieved very simply. First your code:

library(igraph)

actors <- data.frame(name=c("Alice", "Bob", "Cecil", "David",
                            "Esmeralda"))
relations <- data.frame(from=c("Bob", "Cecil", "Cecil", "David",
                               "David", "Esmeralda"),
                        to=c("Alice", "Bob", "Alice", "Alice", "Bob", "Alice"),
                        friendship=c(4,15,5,2,11,1))
g <- graph_from_data_frame(relations, directed=TRUE, vertices=actors)

Now let's create a graph with a thickness of 2, line color black and line type 2.

plot(g, edge.width = 2, edge.color = "black", edge.lty = 2)

enter image description here

Of course, you can change it as you like

plot(g, edge.width = 5, edge.color = "black", edge.lty = 1)

enter image description here

Hope that's what you meant.

Small update

Finally, you may want to find the coordinates of the elements. You can do it this way:

coords = layout_nicely(g)
coords[5,]=c(20, 20)
coords

output

         [,1]     [,2]
[1,] 15.21285 18.97650
[2,] 15.18511 20.08411
[3,] 14.21575 19.70269
[4,] 16.17453 19.75255
[5,] 20.00000 20.00000

Plot

plot(g, layout=coords, edge.width = 5, edge.color = "black", edge.lty = 1)

enter image description here

You can also set other cutout attributes

plot(g, vertex.size = 20, vertex.color = "red", vertex.shape = "square", 
     edge.width = 3, edge.color = "black", edge.lty = 3, 
     edge.label = relations$friendship, edge.curved = TRUE)

enter image description here

Also note that any of these parameters can also come from a vector. So there is no obstacle for the thickness to come from the variable friendship, for example.

plot(g, vertex.size = 20, vertex.color = "red", 
     vertex.shape = c("square","circle","square","circle","rectangle"), 
     edge.width = relations$friendship, edge.color = "black", edge.lty = c(1,2,3,1,2,3), 
     edge.label = 10:20, edge.curved = TRUE)

enter image description here

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