@r-project.org [mailto:r-help-boun...@r-project.org] On
Behalf Of Jonathan
Sent: Monday, April 26, 2010 2:53 PM
To: Dennis Murphy
Cc: r-help
Subject: Re: [R] reordering of matrix rows to maximize the sum of the
diagonal
Hi Dennis,
Thanks for the idea, but the order of the rowSums does not
nece
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,]1 501
[2,]11 20
[3,] 3011
> a[order(rowSum
Hi:
How about this? Calling your matrix a,
a[order(rowSums(a)), ]
[,1] [,2] [,3]
[1,]912
[2,]2 111
[3,]34 13
HTH,
Dennis
On Fri, Apr 23, 2010 at 1:10 PM, Jonathan wrote:
> Hi r-help community,
>This question isn't so much a syntax/coding one, but here
Hi Dimitris,
This code is very helpful, although I note that the columns are not
preserved, ie if
> M <- matrix(sample(13, 9, TRUE), 3, 3)
produces:
> M
[,1] [,2] [,3]
[1,] 1392
[2,] 101 12
[3,] 1167
then
> n <- ncol(M)
> ind <- apply(M, 2, which.max)
> maxs
David, I'm not entirely sure at first glance (guess this is part of
the problem!), but after a little searching around, it does look like
this can be addressed using the "Hungarian algorithm," which reorders
the rows of a (square) matrix to minimize the sum of the elements
along the diagonal (the t
one way is:
M <- matrix(sample(13, 9, TRUE), 3, 3)
n <- ncol(M)
ind <- apply(M, 2, which.max)
maxs <- M[cbind(ind, 1:n)]
diags <- diag(M)
diag(M) <- M[cbind(ind, 1:n)]
M[cbind(ind, 1:n)] <- diags
M
I hope it helps.
Best,
Dimitris
On 4/23/2010 10:10 PM, Jonathan wrote:
Hi r-help community,
Can you specify how you would re-order this matrix:
matrix(1:16, 4,4)
> apply(mtx, 2, which.max)
[1] 4 4 4 4
--
David.
On Apr 23, 2010, at 4:10 PM, Jonathan 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 dim
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] [,
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