[R] minimum from matrix

[Schmitt, Corinna]

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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