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.
> 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
>> - 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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