[R] minimum from matrix
Schmitt, Corinna
Corinna.Schmitt at igb.fraunhofer.de
Tue May 8 14:49:50 CEST 2007
Hallo,
I added one row:
> a=rbind(a,1:4)
> a
[,1] [,2] [,3] [,4]
[1,] 0 1 2 0
[2,] 2 3 0 4
[3,] 0 0 3 0
[4,] 0 3 5 0
[5,] 1 2 3 4
And how looks like the command for the minimum of the rows? The result should be minOfRows = 0 0 0 0 1
Thanks,
Corinna
-----Ursprüngliche Nachricht-----
Von: r-help-bounces at stat.math.ethz.ch [mailto:r-help-bounces at stat.math.ethz.ch] Im Auftrag von Gabor Csardi
Gesendet: Dienstag, 8. Mai 2007 14:03
An: oarabile at stams.strath.ac.uk
Cc: r-help at stat.math.ethz.ch
Betreff: Re: [R] minimum from matrix
apply(a, 2, function(x) min(x[x!=0]) )
should do it. Might need some improvement if all numbers in a column
can be zero, try it.
Gabor
On Tue, May 08, 2007 at 09:50:43AM +0100, oarabile at stams.strath.ac.uk wrote:
>
>
> I have a very large matrix with columns that have some of their
> entries as zero
>
>
> A small example if a=
>
> [,1] [,2] [,3] [,4]
> [,1] 0 2 0 0
> [,2] 1 3 0 3
> [,3] 2 0 3 5
> [,4] 0 4 0 0
>
> and what to get the minimum number from each column but that number
> should not be zero. If I use apply (a,2,min) I will get a vector of
> zeros as the minimum but what I want it for example from column 1 I
> should get 1 i.e for all the matrix I should get a vector (1,2,3,3). I
> wonder if someone can give an idea on how to go about it.
>
> thanks in advance for your help.
>
> Oarabile
>
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--
Csardi Gabor <csardi at rmki.kfki.hu> MTA RMKI, ELTE TTK
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