[R] For loop

Joshua Wiley jwiley.psych at gmail.com
Sun Oct 31 02:00:46 CET 2010


Hi,

In general, the way to speed up for loops in R is to avoid them.  It
looks like some of the operations could be vectorized (e.g., h[1,k] +
vv[j-1,k+1] looks like you could just add entire columns at once).  If
you provide sample data for all the variables in your loop, it will be
possible to give you more detailed feedback.

Cheers,

Josh

2010/10/30 20c <20c at email.it>:
> Hi all,
>
> how can i make the following loop faster?
>
> vv[20001,22]=v[20001,22]
> for(k in 21:1) {
>  for(j in 20001:2) {
>   vv[j-1,k+1]=min(xx[j-1]*v[j-1,k+1],vv[j,k+1])
>   v[j,k]=h[1,k]+vv[j-1,k+1]
>  }
> vv[20001,k]=v[20001,k]
> }
>
>
>
> Thanks
>
> Lorenzo
>
>
>
>
>
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-- 
Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles
http://www.joshuawiley.com/



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