Using loop for applying function on matrix

You could also use:

? sapply(seq_len(ncol(mdat)),function(i) mdat[,i]*100/x[i])
#????????? [,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
A.K.

----- Original Message -----
From: Suparna Mitra <suparna.mitra.sm at gmail.com>
To: Pascal Oettli <kridox at ymail.com>
Cc: r-help at r-project.org
Sent: Tuesday, May 21, 2013 5:19 AM
Subject: Re: [R] Using loop for applying function on matrix

Thanks for your reply Pascal.
? I am presently using it with sweep. But here in the question I just gave
one simple example. In reality I need several functions to run. Thus I
was wondering, if without sweep, I can use loop. Also want to learn how to
do this using loop.
Any help will be really great,
Thanks,
Mitra

Dr. Suparna Mitra
Department of Molecular and Clinical Pharmacology
Institute of Translational Medicine University of Liverpool
Block A: Waterhouse Buildings
1-5 Brownlow Street
Liverpool
L69 3GL

Tel.? +44 (0)151 795 5414
M: +44 (0) 7523228621
Internal ext: 55401

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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and provide commented, minimal, self-contained, reproducible code.