[R] What is the matrix version of min()

[Robin Hankin]

Tong

you need to use apply().  The second argument specifies whether
you want to work with rows or columns.  The point of this is that
min() and max() operate on vectors and give a single value,
and you want to "apply" this function to all rows or all columns:

 > a <- matrix(rnorm(30),5,6)
 > apply(a,2,max)
[1] 2.6413241 0.9842076 1.7989560 0.6999855 2.0542201 0.1162821
 > apply(a,1,max)
[1] 1.1771370 0.9811693 2.6413241 0.9842076 2.0542201
 >

HTH

rksh


On 6 Sep 2006, at 09:37, Tong Wang wrote:

> Hi,
>     Is there a function which operates on a matrix and return a  
> vector of min/max of each rol/col ?
> say,  X=  2,  1
>                 3,  4
> min.col(X)=c(2,1)
>
> thanks a lot.
>
> tong
>
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--
Robin Hankin
Uncertainty Analyst
National Oceanography Centre, Southampton
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