[R] Using loop for applying function on matrix

[Pascal Oettli]

Hi,

?sweep

mdat <- 
matrix(c(1,11,2,10,5,2,12,3,9,6,3,13,4,8,7,4,10,5,9,8,5,10,6,10,4),5,5)
x <- c(14,15,10,11,18)

sweep(mdat*100, 2, x, FUN='/')
           [,1]     [,2] [,3]     [,4]     [,5]
[1,]  7.142857 13.33333   30 36.36364 27.77778
[2,] 78.571429 80.00000  130 90.90909 55.55556
[3,] 14.285714 20.00000   40 45.45455 33.33333
[4,] 71.428571 60.00000   80 81.81818 55.55556
[5,] 35.714286 40.00000   70 72.72727 22.22222

Hope this helps,
Pascal


On 05/21/2013 04:16 PM, Suparna Mitra wrote:
> Hello R Experts,
>    I need a bit of help in using loop.
> I have a matrix onto which I need to use several functions.
>
> In a simplified form suppose my matrix is
>> mdat
>       [,1] [,2] [,3] [,4] [,5]
> [1,]    1    2    3    4    5
> [2,]   11   12   13   10   10
> [3,]    2    3    4    5    6
> [4,]   10    9    8    9   10
> [5,]    5    6    7    8    4
>
> And I have one vector
>> x
> [1] 14 15 10 11 18
>
> Now suppose in simple form I want to create a matrix in which each col
> value will be divided with consecutive no from vector x. For example
>
> column 1 of new vector will be C1=mdat[,1]*100/x[1]
>
>> C1
> [1]  7.142857 78.571429 14.285714 71.428571 35.714286
>
> Now how can I use the loop to have the complete vector at a time?
> I tried something like this, but in vain.
> for(i in 1:5) {
> Data=(mdat[,i]*100/x[i], add=T)
> }
>
> Any help will be really great.
> Thanks,
> Mitra
>
> 	[[alternative HTML version deleted]]
>
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