[R] minimum from matrix

[Dimitris Rizopoulos]

try this:

apply(a, 2, function(x) min(x[x > 0]))


I hope it helps.

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: <oarabile at stams.strath.ac.uk>
To: <r-help at stat.math.ethz.ch>
Sent: Tuesday, May 08, 2007 10:50 AM
Subject: [R] minimum from matrix


>
>
> 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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> and provide commented, minimal, self-contained, reproducible code.
> 


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