[R] minimum from matrix
Gabor Csardi
csardi at rmki.kfki.hu
Tue May 8 14:02:49 CEST 2007
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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