[R] Improving effeciency - better table()?

[Simon Cullen]

On Tue, 6 Jul 2004 09:02:26 -0400, Liaw, Andy <andy_liaw at merck.com> wrote:

> Since you didn't provide an example of what z.trun and breaks may look  
> like, most people can only guess.  Before asking how code can be made  
> more
> efficient, it might be more helpful to find out where in the code is  
> taking
> time.  Try:
>
> Rprof()
> obs <- table(cut2(z.trun, cuts=breaks))
> Rprof(NULL)
> summaryRprof()

Thanks, Andy. That helped to clear up some of my confusion. I have now  
eliminated the call to cut2 and table and replaced that with hist, as  
suggested by Roger Peng.

However I had changed much more code than I had initially realised and it  
seems that the other code is having a larger effect. I've attached the  
output of an experiment (a power test with 1000 iterations - code  
included) and it seems that the problem is getting the expected number of  
observations in each cell. I have to integrate the density that I am  
working with in order to do this as it isn't standard.

I know that, firstly, using a for() loop is bad but the problem didn't  
lend itself to vectorisation (I thought). Any help would be appreciated.

-- 
SC

Simon Cullen
Room 3030
Dept. Of Economics
Trinity College Dublin

Ph. (608)3477
Email cullens at tcd.ie