Hello Tamas, and thanks for your answer. I was thinking of something like that, since the networks are lattices and this case is mentionned in the documentation. I also had noticed the "nobigint" parameter for the "betweenness" functions, however it does not exist for the "edge.betweenness" functions. Best, Vincent
> Hello, > > The negative values are most likely due to integer overflows (i.e. the> > betweenness score would be too large and the underlying variable in> which > igraph computes the betweenness score overflows). You can get> around this by > passing nobigint=FALSE to the edge betweenness call -> it will make igraph > use "big integers", which can hold arbitrarily> large numbers at the expense > of being somewhat slower. > > As for the NaNs, it could be a bug, but let's see first whether the > issue persists with nobigint=FALSE. If so, let us know and try to post > a small example on which we could reproduce the issue with NaNs. > > T. > > > > On Sat, Sep 12, 2015 at 3:08 PM, Vincent Labatut > <address@hidden> wrote: >>* Hello,* >> >>* I am processing the edge-betweenness of various networks using R igraph* >>* version 7.1. Those are spatial networks (each node has a (x,y) position) >>and* >>* I am using the "weight" option of the "edge.betweenness" function to take* >>* the spatial distances into account. This spatial distance is stored in an* >>* edge attribute called "dist".* >> >>* Here is the command I use:* >>* edge.betweenness(graph=g, weights=E(g)$dist)* >> >>* However, for some of my networks, I get negative values, or even NaN. Here* >>* are two examples, under the graphml format:* >>* http://dx.doi.org/10.6084/m9.figshare.1540708 >><http://dx.doi.org/10.6084/m9.figshare.1540708>* >>* - scale=32.graphml* >>* - scale=41.graphml* >> >>* For the first one, the first values returned by "edge.betweenness" are:* >>* [1] 1904887544.08 1904887544.08 1896303182.39 1951787568.72 >>1203043060.76* >>* [6] 1270869072.68 622780616.09 667964773.27 279064394.68 >>309184936.21* >>* [11] 135403467.81 155266075.94 51600202.02 60120695.31 >>21113003.39* >>* [16] 24783603.89 6275147.30 6937885.52 1347425.01 >>1002544.99* >>* [21] 150574.42 -327097.77 -711849.38 -1430744.36 >>-246214.20* >>* [26] -602827.15 -230344.97 -484630.12 -297768.08 >>-492364.06* >> >>* For the second one, all the returned values are NaN.* >> >>* Note that all these weights are positive by definition. They even are* >>* non-zero since no two nodes hold the same position, by construction. I also* >>* checked this programmatically. Moreover, there are no multiple links, also* >>* by construction (and I checked with "has.multiple").* >> >>* I was wondering if the negative or NaN values I get are due to me misusing* >>* the function, or if this is a bug in igraph.* >> >>* Thanks,* >>* Vincent Labatut* >> >>* _______________________________________________* >>* igraph-help mailing list* >>* address@hidden* >>* https://lists.nongnu.org/mailman/listinfo/igraph-help >><https://lists.nongnu.org/mailman/listinfo/igraph-help>* >> On Sat, Sep 12, 2015 at 3:08 PM, Vincent Labatut <[email protected]> wrote: > Hello, > > I am processing the edge-betweenness of various networks using R igraph > version 7.1. Those are spatial networks (each node has a (x,y) position) > and I am using the "weight" option of the "edge.betweenness" function to > take the spatial distances into account. This spatial distance is stored in > an edge attribute called "dist". > > Here is the command I use: > edge.betweenness(graph=g, weights=E(g)$dist) > > However, for some of my networks, I get negative values, or even NaN. Here > are two examples, under the graphml format: > http://dx.doi.org/10.6084/m9.figshare.1540708 > - scale=32.graphml > - scale=41.graphml > > For the first one, the first values returned by "edge.betweenness" are: > [1] 1904887544.08 1904887544.08 1896303182.39 1951787568.72 > 1203043060.76 > [6] 1270869072.68 622780616.09 667964773.27 279064394.68 > 309184936.21 > [11] 135403467.81 155266075.94 51600202.02 60120695.31 > 21113003.39 > [16] 24783603.89 6275147.30 6937885.52 1347425.01 > 1002544.99 > [21] 150574.42 -327097.77 -711849.38 -1430744.36 > -246214.20 > [26] -602827.15 -230344.97 -484630.12 -297768.08 > -492364.06 > > For the second one, all the returned values are NaN. > > Note that all these weights are positive by definition. They even are > non-zero since no two nodes hold the same position, by construction. I also > checked this programmatically. Moreover, there are no multiple links, also > by construction (and I checked with "has.multiple"). > > I was wondering if the negative or NaN values I get are due to me misusing > the function, or if this is a bug in igraph. > > Thanks, > Vincent Labatut >
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