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

Robin Hankin r.hankin at noc.soton.ac.uk
Wed Sep 6 10:42:11 CEST 2006


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
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting- 
> guide.html
> and provide commented, minimal, self-contained, reproducible code.

--
Robin Hankin
Uncertainty Analyst
National Oceanography Centre, Southampton
European Way, Southampton SO14 3ZH, UK
  tel  023-8059-7743



More information about the R-help mailing list