[R] how to speed up this for loop?

bartjoosen bartjoosen at hotmail.com
Tue Jul 22 10:20:43 CEST 2008

I'm not sure if I understand correct, but maybe something like:

apply(dat,2,function(x) sum(x[x<0]))

Please do read the posting guide and post a small, working example!!!


Rheannon wrote:
> Could anyone tell me a better way to achieve the output of this for loop?
> It seems to run quite slow. I'm sure there must be a more consise way to
> sum from FN to LN, excluding positive values, for each row.
> #sum between FN and LN, excluding positive values
> for(i in 1:R){
> for(j in FN[i]:LN[i]){
> if(Temp[i,j]<0)
> sum[i] <- sum[i] + sum(Temp[i,j])}}
> Cheers, 
> R

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