numpy int64 cannot be used for indexing VertexSeq

[Subhasis Ray]

Though there is no reference to numpy in the igraph docs, it is common to use numpy with python-igraph. The integer type returned by many numpy functions on 64 bit systems is numpy.int64. When such numbers are used for indexing a VertexSeq in igraph, the error:
KeyError: 'Attribute does not exist'

appears. This causes hard-to-track bugs in the python script. Common use case is,

g = igraph.Graph()
# Add some vertices and edges to g
sp = g.shortest_paths()
# Now we want to find paths shorter than some cutoff
sources, targets = numpy.nonzero(numpy.array(sp) < cutoff)
# Now we want to print some attributes of those vertices
for source_index, target_index in zip(sources, targets):
    print g.vs[source_index]['name'], g.vs[targte_index]['name']

[Tamás Nepusz (ntamas)]

Fixed in https://github.com/igraph/igraph/commit/b0f66975ce215136a6e8b90c186795a43cf4443a

[Gábor Csárdi (gabor.csardi)]

The development of igraph has moved to github, so please do not comment on this bug here. You are of course welcome to comment on github, here:
https://github.com/igraph/igraph/issues/258