Hi Bob, On Wed, Jul 3, 2013 at 7:29 AM, Bob Pap <[email protected]> wrote:
> Hi Tamás, Thanks for the clarification on the treatment of weights in > short distance calculation (the bigger, the further/'lower-value'), and > flow-related and community detection algorithms (the bigger the more > capacity/similar). This is very helpful. I should also assume that any > algorithm using the shortest-paths (e.g. betweenness and/or related > algorithms, possibly also in the community-detection bunch) also weighs > bigger=lower-value? I may need to recheck carefully my calculations and > their interpretation. > > Maybe this information could at some stage be inserted in the help pages - > I have been perplexed in the different calculations, and would be good to > know looking at the documentation. Many thanks! > fair point, I'll add a github issue for this. On the other hand, you can just create a small graph with 4 vertices to see how the weights work in various functions. It is always good to try your analysis on small graphs where you already know the correct results, irrespectively of what any given piece of software is telling you it is doing. Gabor > > Bob > > Kindly, > Bob Pap > > > On 3 July 2013 12:10, Tamás Nepusz <[email protected]> wrote: > >> Hi, >> >> Weights are treated as distances during shortest path calculations -- >> this is what "makes sense" in that domain because you can simply add the >> distances of individual edges in order to get the distance of the whole >> path and you cannot do the same thing if weights were considered as >> similarities. On the other hand, weights are treated as "capacities" in >> flow-related igraph functions and they are treated as "similarity" scores >> in community detection. >> >> -- >> T. >> >> On 3 Jul 2013, at 12:05, Bob Pap <[email protected]> wrote: >> >> > Dear all, >> > I have a brief question on the treatment of weights in calculating >> shortest paths. Are weights considered 'distances' or the opposite - i.e. >> if the weights are flows and I would consider to vertices close to each >> other if the weight is large, is shortest path doing the opposite? I would >> think that weights are treated in the same way throughout, making the >> question particularly relevant. >> > >> > Many thanks for solving this small (but important!) point. >> > Kindly, >> > Bob Pap >> > _______________________________________________ >> > igraph-help mailing list >> > [email protected] >> > https://lists.nongnu.org/mailman/listinfo/igraph-help >> >> >> _______________________________________________ >> igraph-help mailing list >> [email protected] >> https://lists.nongnu.org/mailman/listinfo/igraph-help >> > > > _______________________________________________ > igraph-help mailing list > [email protected] > https://lists.nongnu.org/mailman/listinfo/igraph-help > >
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