Hi,
Sorry, I forgot, I am working in Python.
> 1. Find all vertices with degree 1 and store their IDs in a list. (Use
> igraph_degree in C, degree() in R, Graph.degree() in Python)
Got it. This is easy.
> 2. Find all the edges connecting these vertices.
> Graph.es.select(_within=vertices) in Python.
Aha. I'll try this. Did not know about "_within"
> 3. Delete the selected edges. (the delete() method of whatever was returned
> by Graph.es.select(...) in Python).
Ok great. I'll let you know if I get it to work.
> layout = g.layout("fr")
> g.vs["x"], g.vs["y"] = zip(*layout)
Thanks! That helps me out a lot!
Best,
Ryanne
On Thursday, 15 November 2012 at 16:24, Tamás Nepusz wrote:
> Hi,
>
> You did not mention whether you are working with igraph in C, R or Python so
> I can give you only some generic ideas:
>
> > I want to filter a graph that I made. If a vertex has a degree 1 and is
> > connected to another vertex who has also got degree 1 -> delete both
> > vertices (and also the corresponding edge).
> >
> > But if a vertex has a degree 1 and is connected to a vertex with degree > 1
> > do not delete the vertex.
> 1. Find all vertices with degree 1 and store their IDs in a list. (Use
> igraph_degree in C, degree() in R, Graph.degree() in Python)
>
> 2. Find all the edges connecting these vertices. (Use igraph_es_fromto in C,
> E(g)[vertices %--% vertices] in R, or Graph.es.select(_within=vertices) in
> Python.
>
> 3. Delete the selected edges. (Use igraph_delete_edges in C, delete.edges in
> R, or the delete() method of whatever was returned by Graph.es.select(...) in
> Python).
>
> > Second,
> > I want to layout the graph but I want to add the coordinates as attributes
> > to the nodes instead of plotting it as an image file. How to go about this?
> > I cannot find any examples.
> >
>
> The layout algorithms in igraph (e.g., layout.fruchterman.reingold in R)
> simply return a matrix. Just assign these to the vertices as attributes.
>
> In R:
>
> layout <- layout.fruchterman.reingold(g)
> V(g)$x <- layout[,1]
> V(g)$y <- layout[,2]
>
> In Python:
>
> layout = g.layout("fr")
> g.vs["x"], g.vs["y"] = zip(*layout)
>
> --
> T.
>
>
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>
>
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