[R] minimum of each row in a matrix
Vladimir Eremeev
wl2776 at gmail.com
Tue May 8 15:32:13 CEST 2007
Looks like you are reading manuals and these mailings insufficiently
carefully.
?apply says that if its second argument is 1, it gives you what you want.
Gabor Csardi has also written you this.
If you have several vectors, not a single matrix, you can use pmin:
pmin(a[1,],a[2,],a[3,],a[4,],a[5,])
However, this variant is inefficient in this particular case (lots of
typing, and hardcoded).
Schmitt, Corinna wrote:
>
> Hallo,
>
> I just followed the discussion of the title: minimum from matrix.
> I have a similar problem.
>
>> a=matrix(c(0,2, 0, 0, 1, 3, 0, 3, 2, 0, 3, 5, 0, 4, 0, 0),ncol=4)
>> 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
>>
>> minOfColumns=apply(a, 2, function(x) min(x[x!=0]) )
>> minOfColumns
> [1] 1 1 2 4
>> maxOfColumns=apply(a, 2, function(x) max(x) )
>> maxOfColumns
> [1] 2 3 5 4
>>
>
> How looks like the command for the minimum of the rows? I tried several
> possibilities with apply but did not get the wanted result. The result
> should be minOfRows = 0 0 0 0 1
>
>
--
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