On 25.09.2015 15:51, Christopher Morris wrote:
> Hi,
>
> given a graph G and a subgraph S of G (computed using GraphView). What is the best way to check if a vertex v in V(G) is also in V(S).
>
> Is there are better way than iterating over all vertices in S?
Yes, if you try to obtain a vertex in filtered graph via its index, a
ValueError exception will be raised if this vertex is being filtered
out. For example:
>>> g = Graph()
>>> g.add_vertex(2)
>>> u = GraphView(g, vfilt=lambda v: int(v) < 1)
>>> u.vertex(1)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/count0/.local/lib/python3.4/site-packages/graph_tool/__init__.py", line 1683, in vertex
raise ValueError("Invalid vertex index: %d" % int(i))
ValueError: Invalid vertex index: 1
Hence you could do:
def vertex_belongs(v, g):
try:
g.vertex(int(v))
return True
except ValueError:
return False
Best,
Tiago
--
Tiago de Paula Peixoto <tiago@skewed.de>
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