[R] minimum from matrix

[Gabor Csardi]

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