# [R] Using different function (parameters) with apply

Berend Hasselman bhh at xs4all.nl
Thu Apr 18 09:23:27 CEST 2013

```On 18-04-2013, at 07:20, Sachinthaka Abeywardana <sachin.abeywardana at gmail.com> wrote:

> Hi All,
>
> I have the following problem (read the commented bit below):
>
> a<-matrix(1:9,nrow=3)
>
>
> a
>
>     [,1] [,2] [,3]
> [1,]    1    4    7
> [2,]    2    5    8
> [3,]    3    6    9
>
>
> div<-1:3
>
> apply(a,2,function(x)x/div) ##want to divide each column by div-
> instead each row is divided##
>
>
>     [,1] [,2] [,3]
> [1,]    1  4.0    7
> [2,]    1  2.5    4
> [3,]    1  2.0    3
>

column 1 is c(1,2,3) and divided by your vector div gives the first column c(1/1,2/2,3/3) = c(1,1,1) and that is correct.
column 3 is c(7,8,9) and divided by vector div gives c(7/1, 8/2 , 9/3) = c(7,4,3). Also correct.

> apply(a,1,function(x)x/div) ##Changing Margin from 2 to 1 does
> something completele weird##         [,1]     [,2] [,3]
> [1,] 1.000000 2.000000    3
> [2,] 2.000000 2.500000    3
> [3,] 2.333333 2.666667    3
>

You are dividing each row by vector div). The result for row 1 is the first column and so forth.
Probably if you did t(…) you would get what you want/expect.

> Any thoughts?
>