[R] Diagonal Submatrices Extraction

Bruno C. bruno.c at inwind.it
Thu Jul 26 18:31:01 CEST 2007

Yes you are right ... an example is mandatory.

So ... I have a matrix of 0 with just a single 1 per row and per column
I need to extract all maximal 'diagonal' submatrices

Let's say I have the following matrix

  A B C D E
a 0 1 0 0 0
b 1 0 0 0 0
c 0 0 1 0 0
d 0 0 0 1 0
e 0 0 0 0 1

well I would like to get, for this example, the two following submatrices
  A B                 C D E
a 0 1               c 1 0 0
b 1 0               d 0 1 0
                    e 0 0 1
Of course some of the extracted submatrices will have in some situations dim=c(1,1) ...

Thanks in advance
> Hi :  I think you need to give an example because I don't understand
> below and my guess is that, since noone else replied,
> I don't think they understood it either. I don't mean to be rude. I've
> just noticed  from being on the list
> That, if something is not clear, people won't even tell you. They just
> won't respond. The list is great
> But people don't want to spend time trying to figure out what you want.
> An example and possibly code is really
> helpful in getting responses.
> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Bruno C.
> Sent: Thursday, July 26, 2007 4:47 AM
> To: R-help
> Subject: [R] Submatrices Extraction
> Hello,
> Given a submatrix containing 0 or 1
> I need to extract the indexes of all the diagonal submatrices so one of
> the two diagonals must contains only 1 for each submatrix ...
> Any help?
> Thanks in advance
> Bruno
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