Hi Dennis,
Thanks for the idea, but the order of the rowSums does not
necessarily correspond to the order of rows that maximizes the "rank"
of the matrix.
Ex:
> a[1:9]<-c(1,1,30,50,1,1,1,20,1)
> a
[,1] [,2] [,3]
[1,] 1 50 1
[2,] 1 1 20
[3,] 30 1 1
> a[order(rowSums(a)),]
[,1] [,2] [,3]
[1,] 1 1 20
[2,] 30 1 1
[3,] 1 50 1
In this case, I would like to rearrange the original matrix into:
[,1] [,2] [,3]
[1,] 30 1 1
[2,] 1 50 1
[3,] 1 1 20
Best,
Jonathan
On Sat, Apr 24, 2010 at 1:24 AM, Dennis Murphy <djmu...@gmail.com> wrote:
> Hi:
>
> How about this? Calling your matrix a,
>
> a[order(rowSums(a)), ]
> [,1] [,2] [,3]
> [1,] 9 1 2
> [2,] 2 11 1
> [3,] 3 4 13
>
> HTH,
> Dennis
>
>
> On Fri, Apr 23, 2010 at 1:10 PM, Jonathan <jonsle...@gmail.com> wrote:
>>
>> Hi r-help community,
>> This question isn't so much a syntax/coding one, but here goes:
>>
>> Let's say I have matrix of arbitrary dimensions and I'd like to
>> reorder the rows in such a way that I could maximize the sum of the
>> entries along the diagonal.
>>
>> For example, for this 3x3 matrix:
>>
>>
>> [,1] [,2] [,3]
>> [1,] 3 4 13
>> [2,] 9 1 2
>> [3,] 2 11 1
>>
>> rearranging the rows to maximize the sum along the diagonal would
>> produce this matrix:
>>
>> [,1] [,2] [,3]
>> [1,] 9 1 2
>> [2,] 2 11 1
>> [3,] 3 4 13
>>
>>
>> I've been experimenting with some scripts of my own, but I figured I'd
>> ask if one of you R-ninjas might know of an existing function (or
>> algorithm I could look up and then code) that can do this somewhat
>> efficiently (or even just correctly!).
>>
>> Best,
>> Jonathan
>>
>> ______________________________________________
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>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>
>
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