Hi,

On Sep 11, 2009, at 6:35 PM, Edward Chen wrote:

example code:
P = function(whichday,columns){
y = which(pvalue[,whichday]<Pvaluetest, arr.ind=TRUE)
dayarb = raw_urine[y,day1_ind]
daystand = raw_urine[y,columns]
meandayxx = geometricmeanRow(dayarb)
meandayyy = geometricmeanRow(daystand)
diff = meandayyy - meandayxx
for(i in 1:nrow(diff)){
if(diff[i]>0){
#diffbig = meandayxx<meandayyy
x_index[i] = which(diff[i]>0)
x[i] = raw_urine[x_index[i],1]
dayx[i]= raw_urine[x_index[i],day1_ind]
dayy[i] = raw_urine[x_index[i],columns]
jpeg("test 1.jpg",width=800, height = 800)
matplot(x[i],dayx[i],lwd = 3,pch=1,col = "black",xlim=xbound, ylim=ybound)
matpoints(x[i],dayy[i],lwd=3,pch=1,col="red")
dev.off()
return(length(y),length(x_index),diffbig)}
else{
xx_index[i] = which(diff[i]<0, arr.ind=TRUE)
xx[i] = raw_urine[xx_index[i],1]
dayxx[i] = raw_urine[xx_index[i],day1_ind]
dayyy[i] = raw_urine[xx_index[i],columns]
jpeg("test 2.jpg",width=800, height = 800)
matplot(xx[i],dayxx[i],lwd = 3,pch=1,col = "black",xlim=xbound, ylim=ybound)
matpoints(xx[i],dayyy[i],lwd=3,pch=1,col="red")
dev.off()
return(length(xx_index))}}}

I ran this code and I got "Error in 1:nrow(diff) : NA/NaN argument". I this
my problem is with the way I define the i index with the rest of the
functions.
Basically I want to run for every row of the matrix that is called the
"diff". without the for loop, I don't know how to make it work but with it, I have a lot of bugs in there that hopefully someone can just point out a
general direction.

Sorry, I can't put the brainpower into figuring out what the code means, but it sounds like you want to run a given function over each row of your matrix, yes?

Look at the ``apply`` function, with MARGIN set to 1. Here I'm just calling the ``mean`` function over every row of my matrix:

R> m <- matrix(1:100, 10, 10)
R> apply(m, 1, mean)
 [1] 46 47 48 49 50 51 52 53 54 55

Substitute your own function for ``mean``

-steve

--
Steve Lianoglou
Graduate Student: Computational Systems Biology
  |  Memorial Sloan-Kettering Cancer Center
  |  Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact

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