How to plot a ellipse node with igraph?

问题

It seems no such questions has ever been asked in SO. However, the help page of igraph on customizing node shapes is rather vague. Can someone provide a complete example of customizing node shape in igraph?

回答1:

You do not say what language you use, so I am going to respond in R.

The shapes that are built-in can be listed with shapes(). Unfortunately, ellipse is not among them. The help page ?shapes gives a few examples of how to add additional node shapes - a triangle, a star and adding an image. The response below is a straightforward modification of the example code for adding a triangle. There are several functions for drawing ellipses. I used the one from the plotrix package.

library(igraph)
library(plotrix)

## Need a graph as an example
set.seed(1)
N10 = erdos.renyi.game(10, 0.31)

## Function for plotting an elliptical node
myellipse <- function(coords, v=NULL, params) {
  vertex.color <- params("vertex", "color")
  if (length(vertex.color) != 1 && !is.null(v)) {
    vertex.color <- vertex.color[v]
  }
  vertex.size <- 1/30 * params("vertex", "size")
  if (length(vertex.size) != 1 && !is.null(v)) {
    vertex.size <- vertex.size[v]
  }

  draw.ellipse(x=coords[,1], y=coords[,2],
    a = vertex.size, b=vertex.size/2, col=vertex.color)
}

## Register the shape with igraph
add_shape("ellipse", clip=shapes("circle")$clip,
                 plot=myellipse)

## Plot it, with different sizes and colors to illustrate
plot(N10, vertex.shape="ellipse", vertex.color=rainbow(vcount(N10)),
     vertex.size=(2:11)/2)

Et voila.

来源：https://stackoverflow.com/questions/48457824/how-to-plot-a-ellipse-node-with-igraph

标签

igraph