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## Re: [igraph] a problem with simplify()

 From: Simone Gabbriellini Subject: Re: [igraph] a problem with simplify() Date: Thu, 21 Oct 2010 19:40:14 +0200

```with as.vector() both gives me 0-based indexing.

> as.vector(V(g))
[1]   0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17
18  19  20  21  22  23  24  25
[27]  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43
44  45  46  47  48  49  50  51

> as.vector(E(g))
[1]   0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17
18  19  20
[22]  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38
39  40  41

I must have a not so recent 0.6.

best,
simo

Il giorno 21/ott/2010, alle ore 19.34, Gábor Csárdi ha scritto:

> On Thu, Oct 21, 2010 at 7:21 PM, Simone Gabbriellini
>> Thanks Tamas, Gabor
>>
>> actually, I should have the 1-based vertex indexing. BTW, the edge indexing
>> is 0-based, right?
>
> No. Either both vertex and edge ids are indexed from zero (0.5 branch)
> or both of them are indexed from one (recent 0.6 branch).
>
>>> V(g)
>> Vertex sequence:
>>  [1] "user138" "user300" "user301" "user290" "user93"  "user145" "user223"
>> "user96"  "user148" "user154"
>>  [11] "user152" "user467" "user104" "user317" "user111" "user143" "user292"
>> "user91"  "user31"  "user90"
>
> This is misleading, try
>
> as.vector(V(g))
>
> Gabor
>
>>
>>> E(g)
>> Edge sequence:
>>
>> [0]   user85  -> user85
>> [1]   user33  -> user33
>>
>>
>> best,
>> simone
>>
>> Il giorno 21/ott/2010, alle ore 19.06, Tamas Nepusz ha scritto:
>>
>>>> Definitely, because your code does not take into account that edges are
>>>> reindexed after every deletion. I'd go for delete.edges(g, seq(0,
>>>> ecount(g)-1)[is.loop(g)])
>>> Or, even better: delete.edges(g, which(is.loop(g))-1) if your igraph
>>> version uses 0-based indexing. Note that  the R interface of igraph 0.6 has
>>> recently switched to 1-based indexing, so if you installed igraph 0.6 in
>>> the last few days, you don't have to subtract 1.
>>>
>>> --
>>> T.
>>>
>>>
>>> _______________________________________________
>>> igraph-help mailing list
>>> http://lists.nongnu.org/mailman/listinfo/igraph-help
>>
>>
>> _______________________________________________
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>>
>
>
>
> --
> Gabor Csardi <address@hidden>     UNIL DGM
>
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