Hi Jean-Patrick,
I think a faster way could be using the degree_property_map associated to
the graph:
kp = T.degree_property_map('out')
and filter it using your favorite function (the first that comes to my mind
is. np.equal(kp.a, np.ones(T.num_vertices(),dtype=np.int)) ).
You can then use the resulting array to select the vertices to inspect. I
expect an equality between N integers to be faster than N append.
Best,
Giuseppe
Il giorno mer 7 ott 2015 alle ore 00:04 jean-patrick <
[email protected]> ha scritto:
> Hello,
>
> Is there an obvious way to collect vertices of degree 1 for reading the
> property of their edge?
>
> The following code succeed in doing the job on a tiny scale, but I am sure
> this not the way to do:
>
> /import graph_tool.all as gt
> #from graph_tool import topology
>
> ## Make a graph
>
> T = gt.Graph(directed = False)
> edge_weights = T.new_edge_property('double')
> T.properties[("e","weight")] = edge_weights
>
> T.add_vertex(n=5)
>
> e_1 = T.add_edge(0,1)
> e_2 = T.add_edge(1,2)
> e_3 = T.add_edge(0,0)
> e_4 = T.add_edge(1,3)
>
> edge_weights[e_1]= 2
> edge_weights[e_2]= 6
> edge_weights[e_3]= 1
> edge_weights[e_4]= 3
>
> ## Get the vertices of degree 1 in a dictionary (keys= vertices degree,
> values=vertices)
>
> from collections import defaultdict
> deg_dic = defaultdict(list)
>
> for v in T.vertices():
> degree = v.out_degree()
> deg_dic[degree].append(v)
>
> ## Read the weight of the bounded edge
>
> print 'vertices of degree 1:'
> for d1 in deg_dic[1]:
> weight_of_bound_edge = [edge_weights[e] for e in d1.out_edges()]
> print 'vertex',d1,' weight of out edge:', weight_of_bound_edge/
>
> By the way, the objective is to count the vertices of degree 1 as a
> function
> of the pruning steps. Is there sucha a function in graph-tool?
>
> Best regards
>
> Jean-Patrick
>
>
>
>
>
>
> --
> View this message in context:
> http://main-discussion-list-for-the-graph-tool-project.982480.n3.nabble.com/A-more-simple-way-to-filter-vertices-of-degree-1-an-the-property-weight-of-their-edge-tp4026295.html
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