Re: [igraph] Understanding the output of stMinCuts

[Tom Wright]

Sorry for the earlier posting,
I'm not sure that the zero weight values are the whole problem. I have
linked another graph (dropbox, graphml format) with a very similar
(although larger) structure with no zero weights that demonstrates the
same problem.

https://db.tt/7s6nRtj0

#this following line might not work and the file will have to be
manually downloaded
g<-read.graph('https://db.tt/7s6nRtj0',format='graphml')

cuts<-stMincut(g,s,t)

On Tue, 2014-06-03 at 22:47 +0200, Gábor Csárdi wrote:
> Actually, the graph would do, I don't really need the code that
> generates it. 
> 
> 
> Anyway, it seems that this is a bug in igraph, it does not handle
> edges with zero weights. A workaround is to replace zero weights with
> something small:
> 
> 
> E(g)$weight <- ifelse(E(g)$weight == 0, 1e-10, E(g)$weight)
> 
> 
> and the output seems to make more sense. I created a bug report for
> this:
> https://github.com/igraph/igraph/issues/628
> 
> 
> 
> Gabor
> 
> 
> 
> 
> 
> 
> On Tue, Jun 3, 2014 at 10:31 PM, Tom Wright <address@hidden> wrote:
>         Hi Gábor,
>         
>         Thank you for taking a look at this.
>         I've posted an example: http://pastebin.com/aUi9vkyk
>         
>         
>         
>         On Tue, 2014-06-03 at 21:58 +0200, Gábor Csárdi wrote:
>         > Please provide a reproducible example.
>         > See
>         
> http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example
>         >
>         >
>         > Thanks, Gabor
>         >
>         >
>         > On Tue, Jun 3, 2014 at 7:02 PM, Tom Wright
>         <address@hidden> wrote:
>         >         Hi,
>         >         This is probably a gap in my knowledge but can
>         someone please
>         >         help me
>         >         understand the output I am getting from the
>         stMincuts
>         >         function?
>         >
>         >         With the example attached I don't understand why cut
>         $cuts[[1]]
>         >         is empty.
>         >
>         >         The graph I am using is pictured in the attachment,
>         all edges
>         >         to
>         >         vertices s & t have value 1, all other edges have
>         value 1000.
>         >
>         >         Thanks,
>         >         Tom
>         >
>         >         > cut<-stMincuts(g,'s','t')
>         >         > cut
>         >         $value
>         >         [1] 5
>         >
>         >         $cuts
>         >         $cuts[[1]]
>         >         numeric(0)
>         >
>         >         $cuts[[2]]
>         >          [1]  89  90  91  92  93  94  95  96  97  98  99 100
>         101 102
>         >         103
>         >
>         >
>         >         $partition1s
>         >         $partition1s[[1]]
>         >         [1] 30 24 18 12  6
>         >
>         >         $partition1s[[2]]
>         >          [1] 30 24 18 12  6 31 29 28 27 26 25 23 22 21 20 19
>         17 16 15
>         >         14 13 11
>         >         10  9  8  7  5  4  3  2  1
>         >
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