[R] efficient way to reduce running time

[Dennis Murphy]

Hi:

Could you please provide a reproducible example? In your code,
  (i) n is undefined;
  (ii) logbp is undefined.
A description of what you want to do and/or a reproducible example
with an expected outcome would be useful.

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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

Dennis

On Tue, Aug 2, 2011 at 4:05 AM, Kathie <kathryn.lord2000 at gmail.com> wrote:
> Dear R users,
>
> Would you plz tell me how to avoid this "for" loop blow??
>
> I think there might be a better way to reduce running time.
>
> ----------------------------------------------------------------------------------------------
> ## y1 and y2 are n*1 vectors
>
>        for (k in 1:n){
>                ymax <- max( y1[k], y2[k] )
>
>                i <- 0:ymax
>
>                sums<- -lgamma(y1[k]-i+1)-lgamma(i+1)-lgamma(y2[k]-i+1)
>
>                maxsums <- max(sums)
>
>                sums <- sums - maxsums
>
>                lsum <- log( sum(exp(sums)) ) + maxsums
>
>                logbp[k] <- y1[k]  + y2[k]  + lsum
>        }
>
> ------------------------------------------------------------------------------------
>
> Any suggestion will be greatly appreciated.
>
> Regards,
>
> Kathryn Lord
>
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