Re: [igraph] Help with write_svg function

[Tamas Nepusz]

On Tue, Apr 13, 2010 at 05:33:25PM +0200, Domenico Conti wrote:
> Hi, I use the following code:
> 
> outFolder = self.mainView.outputFolderText.GetLabelText()
> 
> fileName = outFolder+os.sep+"GRAPH_"+self.fileName+".svg"
> 
> soglia = int(self.mainView.thresholdText.GetValue())
> 
> graph.layout("kamada_kawai")
> 
> graph.es["edge_color"]=[["red", "black"][value>soglia] for value in 
> graph.es["iFlow"]]
> 
> for vertex in graph.vs:
> 
> vertex["vertex_color"] = "green"
> 
> visualStyle = {}
> 
> visualStyle["margin"] = 20
> 
> visualStyle["layout"] = "kamada_kawai"
> 
> visualStyle["edge_color"] = [["red", "black"][value>soglia] for value in 
> graph.es["iFlow"]]
> 
> visualStyle["vertex_color"] = "green"
> 
> graph.write_svg(fileName, layout="kamada_kawai")
> 
> but when I open svg file I can see that my visualStyle are not applied to my 
> graph. Why?
Well, first, because you did not pass it to graph.write_svg; second,
because visualStyle["vertex_color"] must contain as many entries as the
number of vertices in your graph (even if all vertices must have the
same color). So, I'd do this:

visualStyle["vertex_color"] = ["green"] * graph.vcount()
graph.write_svg(fileName, **visualStyle)

Also note that the write_svg method is sort of deprecated; it was meant
to be used in earlier igraph versions when we did not have a proper
plotting support using Cairo. You should use plot(graph, fileName,
**visualStyle) instead, it will automatically know to use the SVG format
because of the file extension. Don't use write_svg unless you cannot
install the Python bindings of Cairo.

-- 
Tamas