Hello Tiago, thank you very much for the suggestions. i'll try to find the way that best fit to my case. Cheers, Elia On Fri, Nov 27, 2009 at 9:29 AM, Tiago de Paula Peixoto <tiago@forked.de>wrote:
Hello Elia,
Elia Bruni wrote:
Hello list,
I am currently working with graph_tool to analyse text documents. let's say that in my graph each vertex is a word that appears in the text and each edge corresponds to a relationship between two words. Because of the fact that vertex is individuated only by its index i suppose to use a vertex property map (let's call it 'name', of type 'string') to put the word related to the vertex, assuring a bijective property of the "word <-> vertex index" function. Intuitively i'd like to do something like idx = g.vertex("example"). I cannot see how to implement it with the PropertyMaps because i can only have the function "vertex index -> word".
I cannot keep the "word -> vertex index" elsewhere because remove_vertex() is changing my indexes under my feet.
Does anybody of you have a suggestion?
There is no simple solution for this if you intend to modify the graph by removing vertices... You have basically two options:
1 - Don't remove the vertex, and instead just mask it out of the graph, with set_vertex_filter(). This way, all vertex objects remain valid, and you can store them as values of a dictionary.
2 - Use the find_vertex() function to find vertices with a given property map value. This is easy, but it is also slow, since every lookup takes O(V) time.
I hope this helps.
Cheers, Tiago
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