Re: [R] Improving effeciency - better table()?

From: Marc Schwartz <MSchwartz_at_medanalytics.com>
Date: Tue 06 Jul 2004 - 23:11:08 EST

On Tue, 2004-07-06 at 07:56, Simon Cullen wrote:
> Hi,
>
> I've been running some simulations for a while and the performance of R
> has been great. However, I've recently changed the code to perform a sort
> of chi-square goodness-of-fit test. To get the observed values for each
> cell I've been using table() - specifically I've been using cut2 from
> Hmisc to divide up the range into a specified number of cells and then
> using table to count how many observations appear in each cell.
>
> > obs <- table(cut2(z.trun, cuts=breaks))
>
> Having done this I've found that the code takes much longer to run - up to
> 10x as long. Is there a more effecient way of doing this? Anyone have any
> thoughts?

It would appear that you might be attempting to do a Hosmer-Lemeshow type of GOF test.

If indeed that is the case, before making the above more efficient, you should spend some time reviewing the following posts by Frank Harrell on this subject:

http://maths.newcastle.edu.au/~rking/R/help/02b/4210.html

http://maths.newcastle.edu.au/~rking/R/help/02b/3111.html

HTH, Marc Schwartz



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