[R] matrix indexing (igraph ?)

[Gábor Csárdi]

This is not an igraph issue, I believe. You need to go over your
indices and update the matrix, i.e.

for (i in seq_along(t.list)) { temp[t.list[i], c.list[i]] <-
temp[t.list[i], c.list[i]] + 1 }

Best,
Gabor

On Tue, Aug 2, 2011 at 4:50 PM, Robinson, David G <drobin at sandia.gov> wrote:
> I realize that matrix indexing has been addressed in various flavors, but I'm stumped and didn't find anything in the archives.  It's not clear if it is an igraph issue or a more general problem. Thanks in advance for your patience.
>
> I am using igraph to read a gml file (http://www-personal.umich.edu/~mejn/netdata/football.zip
> ). The gml file contains vertex attributes (conference and team) that are provided as character/integer values.
>
> I would like to build a matrix of dimension (length.team, length.conference) where the elements are zero except for 1's at the location of index [team, conference].
>
> Here is a snippet of code that hopefully captures what I am trying to do:
>
> original<-read.graph("./Data/football/football.gml", format="gml")
> conf.list<- get.vertex.attribute(original, 'value', index=V(original))+1
> team.list<- get.vertex.attribute(original, 'id', index=V(original))+1
> temp<- matrix(0,115,12)
> temp[team.list, conf.list]<-1
>
> Unfortunately, temp[] is filled with 1's.
>
> However, if I try:
> c.list=c(1,3,5)
> t.list=c(2,4,6)
> temp[t.list,c.list]<-1
>
> then things work as I would expect.  FWIW - I have tried as.integer(get.vertex.attribute(...)) with no luck.
>
> Thanks for any suggestions.
>
>
>
>
> *****************************************************
>> original<-read.graph("./Data/football/football.gml", format="gml")
>> conf.list<- get.vertex.attribute(original, 'value', index=V(original))+1
>> team.list<- get.vertex.attribute(original, 'id', index=V(original))+1
>> conf.list
>  [1]  8  1  3  4  8  4  3  9  9  8  4 11  7  3  7  3  8 10  7  2 10  9  9  8 11  1  7 10 12  2  2  7  3  1  7  2  6
>  [38]  1  7  3  4  8  6  7  5  1 12  3  5 12 11  9  4 12  7  2 10  5 12 11  3  7 10 11  3 10  5 12  9 11 10  7  4 12
>  [75]  4  5 10  9  9  2  6  4  6 12  4  7  5 10 12  1  6  5  5  8  2 10 10 11  4  7  3  2  4  1  8  1  3  4  9  1  5
> [112]  9  5 10 12
>> team.list
>  [1]   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  26  27
>  [28]  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54
>  [55]  55  56  57  58  59  60  61  62  63  64  65  66  67  68  69  70  71  72  73  74  75  76  77  78  79  80  81
>  [82]  82  83  84  85  86  87  88  89  90  91  92  93  94  95  96  97  98  99 100 101 102 103 104 105 106 107 108
> [109] 109 110 111 112 113 114 115
>> length(conf.list)
> [1] 115
>> length(team.list)
> [1] 115
>> temp<- matrix(0,115,12)
>> r<-c(1,3,5)
>> col<- c(2,4,6)
>> temp[r,col]<-1
>> temp[1:10,]
>      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12]
>  [1,]    0    1    0    1    0    1    0    0    0     0     0     0
>  [2,]    0    0    0    0    0    0    0    0    0     0     0     0
>  [3,]    0    1    0    1    0    1    0    0    0     0     0     0
>  [4,]    0    0    0    0    0    0    0    0    0     0     0     0
>  [5,]    0    1    0    1    0    1    0    0    0     0     0     0
>  [6,]    0    0    0    0    0    0    0    0    0     0     0     0
>  [7,]    0    0    0    0    0    0    0    0    0     0     0     0
>  [8,]    0    0    0    0    0    0    0    0    0     0     0     0
>  [9,]    0    0    0    0    0    0    0    0    0     0     0     0
> [10,]    0    0    0    0    0    0    0    0    0     0     0     0
>> temp[team.list,conf.list]<- 1
>> temp[1:10,]
>      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12]
>  [1,]    1    1    1    1    1    1    1    1    1     1     1     1
>  [2,]    1    1    1    1    1    1    1    1    1     1     1     1
>  [3,]    1    1    1    1    1    1    1    1    1     1     1     1
>  [4,]    1    1    1    1    1    1    1    1    1     1     1     1
>  [5,]    1    1    1    1    1    1    1    1    1     1     1     1
>  [6,]    1    1    1    1    1    1    1    1    1     1     1     1
>  [7,]    1    1    1    1    1    1    1    1    1     1     1     1
>  [8,]    1    1    1    1    1    1    1    1    1     1     1     1
>  [9,]    1    1    1    1    1    1    1    1    1     1     1     1
> [10,]    1    1    1    1    1    1    1    1    1     1     1     1
>>
>> ---------------------------------------------
>
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-- 
Gabor Csardi <csardi at rmki.kfki.hu>     MTA KFKI RMKI