Thanks a lot for the explanations. I am going to give it a try in the next few days.
On Mon, Apr 15, 2013 at 1:09 AM, Tamas Nepusz <nta...@gmail.com> wrote: > Hi, > > > Let's say the vertexes are from 1 to N, > igraph vertex and edge indices are zero-based (which is the standard > convention in C anyway so I guess this did not strike you as a surprise > ;)). > > > the edges, but I don't understand what is the format that igraph accepts. > > For instance, one way would be to put all the edges in a huge array of > pairs > > (X, Y) where there is an edge from X to Y. The array would contain: 0, > 1, 0, > > 2, 1, 3, 1, 4 etc where (0, 1), (0, 2), (1, 3), (1, 4) etc are all > edges. > This is the format that igraph requires. Use an igraph_vector_t to store > the > edge list and then call igraph_create to construct your graph: > > http://igraph.sourceforge.net/doc/html/ch09s01.html#igraph_create > > An alternative way you could use is an adjacency list where you will > basically have 80 million vectors, and the ith vector stores the neighbors > of vertex i. The constructor to use is igraph_adjlist: > > http://igraph.sourceforge.net/doc/html/ch09s01.html#igraph_adjlist > > igraph_adjlist requires you to use our igraph_adjlist_t data structure, > though. You have to construct an empty adjacency list first with > igraph_adjlist_init_empty -- this also created all the 80 million vectors > for you. You can then get the i-th vector using igraph_adjlist_get and add > new neighbors to it using igraph_vector_push_back. Once you set up the > adjacency list, you can call igraph_adjlist to turn that into an igraph_t > (which is an indexed edge list by the way, but this is an implementation > detail that you shouldn't care about). Finally, you can throw the > igraph_adjlist_t away by calling igraph_adjlist_destroy. Relevant links > from > the documentation: > > http://igraph.sourceforge.net/doc/html/igraph-Adjlists.html > http://igraph.sourceforge.net/doc/html/igraph-Vectors.html > > -- > T. > > _______________________________________________ > igraph-help mailing list > igraph-help@nongnu.org > https://lists.nongnu.org/mailman/listinfo/igraph-help >
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