Re: [R] how to speed up this for loop?

From: Nordlund, Dan (DSHS/RDA) <NordlDJ_at_dshs.wa.gov>
Date: Tue, 22 Jul 2008 12:18:42 -0700

> -----Original Message-----
> From: r-help-bounces_at_r-project.org
> [mailto:r-help-bounces_at_r-project.org] On Behalf Of Nordlund,
> Dan (DSHS/RDA)
> Sent: Tuesday, July 22, 2008 10:31 AM
> To: r-help_at_r-project.org
> Subject: Re: [R] how to speed up this for loop?
>
> > -----Original Message-----
> > From: r-help-bounces_at_r-project.org
> > [mailto:r-help-bounces_at_r-project.org] On Behalf Of Rheannon
> > Sent: Tuesday, July 22, 2008 9:09 AM
> > To: r-help_at_r-project.org
> > Subject: Re: [R] how to speed up this for loop?
> >
> >
<<<snip>>>

> > #******This is the loop that I would like to speed up************
> >
> > #sum values 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])}}
> >
>
> Using sum for a matrix name was very confusing to my eyes
> trying to differentiate square brackets from parentheses.
> You may have even confused yourself. However, does this get
> you close to what you want?
>
> #sum values between FN and LN, excluding positive values
> for(i in 1:R){
> sum[i] <- sum(Temp[i,Temp[I,FN[i]:LN[i]]>0]) }
>
I hope it was obvious, but there is an upper case 'I' in the summation that should be lower case.

 for(i in 1:R){
   sum[i] <- sum(Temp[i,Temp[i,FN[i]:LN[i]]>0]) }

Dan

Daniel J. Nordlund
Washington State Department of Social and Health Services Planning, Performance, and Accountability Research and Data Analysis Division
Olympia, WA 98504-5204    



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