On Mon, Feb 24, 2014 at 9:29 AM, [email protected] <[email protected]>wrote:
> Hi! > > Thanks for your kind reply. But I still have two question about the > function subcomponent( ): > > 1. Should not the result of " subcomponent(g, 4, "all")" be the union of > "subcomponent(g, 4, "in")" and "subcomponent(g, 4, "out")"? > No. Just calculate it by hand for your graph. > 2. The graph is a directed network with 10 vertices and 10 edges and the > vertice 0 is an isolated node. > Yes, because vertices are numbered from zero in an 'edgelist' file. > Even if 4 in the source code is 5 in the graph, the result of > subcomponent(g, 4, "out") is supposed to be NULL, because there is > no vertice could be reached from vertice 5 in graph. > You need to add one to the numbers in the file, to get the ids in R igraph. So when you write subcomponent(g, 4, "out") that belongs to vertex 3 in your file. Which does have an outgoing edge, so subcomponent(g, 4, "out") will be c(4, 3) I guess The result will never be NULL, anyway, as it always contains the vertex itself. G. > > Here is the graph: > 1 5 > 1 7 > 3 2 > 4 5 > 4 7 > 4 9 > 9 4 > 6 9 > 8 7 > 9 2 > > best > Xueming > > ------------------------------ > [email protected] > > *From:* Gábor Csárdi <[email protected]> > *Date:* 2014-02-23 23:42 > *To:* Help for igraph users <[email protected]> > *Subject:* Re: [igraph] Error in using the function subcomponent( ) > Hi! > > > On Sun, Feb 23, 2014 at 9:43 AM, [email protected] > <[email protected]>wrote: > >> Hello! >> >> I am trying to use the subcomponent() to find the in-component and >> out-component from a given vertice. >> Here is the source code and result: >> >> > g<-read.graph("input.txt", "edgelist") >> > > The "edgelist" file format is indexed from zero, so what is 4 in your file > will be 5 in your graph. > > Gabor > > >> > subcomponent(g, 4, "in") >> [1] 4 >> > subcomponent(g, 4, "out") >> [1] 4 3 >> > subcomponent(g, 4, "all") >> [1] 4 3 10 5 7 6 8 2 9 >> >> Here is the input file "input.txt" (a directed network with 10 nodes >> and 10 edges): >> 1 5 >> 1 7 >> 3 2 >> 4 5 >> 4 7 >> 4 9 >> 9 4 >> 6 9 >> 8 7 >> 9 2 >> >> But the actual result is should be: >> subcomponent(g, 4, "in"): 4 6 9 >> subcomponent(g, 4, "out"): 2 4 5 7 9 >> subcomponent(g, 4, "all"): 2 4 5 6 7 9 >> >> Why is the results computed by using the function subcomponent( ) >> different from the actual result? >> >> best >> Xueming >> >> ------------------------------ >> [email protected] >> >> _______________________________________________ >> 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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