On 27.04.2015 22:23, Krister wrote:
> Thanks for the quick response Thiago!
>
> In this code all the edges and vertices are created by graph-tool and the result is something much faster...
>    is this the best I can do?
>
> It's somewhat annoying to have to keep track of the vertices that will be created like this:
>
> def graph_tool_create_all_at_once():
>   """ Create a graph_tool graph given a list of pairs. """
>   G = Graph(directed=False)
>   objectTOi = {}
>   vertexpairs = []
>   counter = 0
>   for o1,o2 in get_pairs_of_ints():
>     if(o1 in objectTOi):
>       u = objectTOi[o1]
>     else:
>       u = counter
>       counter += 1
>       objectTOi[o1] = u
>     if(o2 in objectTOi):
>       v = objectTOi[o2]
>     else:
>       v = counter
>       counter += 1
>       objectTOi[o2] = v
>
>     vertexpairs.append((u,v))
>
>   G.add_edge_list(vertexpairs)

Yes, it is possible to improve this. If your o1 and o2 objects are
always ints (as I gather from get_pairs_of_ints()), then you don't need
these dictionaries at all. The G.add_edge_list() will create missing
nodes as necessary. So you only need to do:

   G.add_edge_list(list(get_pairs_of_ints()))

This will be much faster. However it requires your ints to be within
some reasonable range, since missing ints without edges will also be
created. But you are better off guaranteeing this is the case when you
generate the ints in the first place.

Best,
Tiago

--
Tiago de Paula Peixoto <tiago@skewed.de>

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