
From:  Gábor Csárdi 
Subject:  Re: [igraph] accessing edge attributes via vertex indices? 
Date:  Thu, 9 Jan 2014 09:53:29 0500 
This is related to my previous question about combining vertex attributes (thanks Tamas for the insight in figuring that out), but relates to operations on edges.I have an undirected graph gA, with no loops and no multiple edges. Each edge of the graph has a vector of attributes, e.g. E(gA)$weight . I would like to be able to find the attributes of the edge that connects two specific vertices. Something similar would happen in the following very simplified R code snippet:sum<0for (i in 1:vcount(gA) {for (j in 1: vcount(gA) {sum < sum+ E(gA)[from(i) & to(j)]$weight}}A couple of issues arise: Ideally, I would like to only do this when an edge exists between i and j exist, but I cannot seem to find a logic statement that returns either TRUE/FALSE. The second issue occurs when i=j where the result of E(gA)[from(i) & to(j)] is multiple values.I think that the problem boils down to the question: given two vertices, can I determine if an edge exists between them and, if so, what is the index of the edge between them?Thanks again for all the help,David
_______________________________________________
igraphhelp mailing list
address@hidden
https://lists.nongnu.org/mailman/listinfo/igraphhelp
[Prev in Thread]  Current Thread  [Next in Thread] 