Hi,
Sorry, forgot to mail back.
> 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.
> Graph.es.select(_within=vertices) in Python.
> 3. Delete the selected edges. (the delete() method of whatever was returned
> by Graph.es.select(...) in Python).
This worked perfectly. In addition I would suggest the following steps. For me
the vertices were not deleted automatically when deleting the corresponding
edges.
4. Re-calculate the degree of each vertex after deleting the edges
5. Delete the vertices that have degree = 0
Thanks again for your help.
Best,
Ryanne
On Thursday, 15 November 2012 at 16:30, Ryanne Turenhout wrote:
> 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.
> >
> >
> > _______________________________________________
> > igraph-help mailing list
> > [email protected] (mailto:[email protected])
> > https://lists.nongnu.org/mailman/listinfo/igraph-help
> >
> >
> >
>
>
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