| To: | s-news@lists.biostat.wustl.edu |
|---|---|
| Subject: | tapply() on columns of matrix |
| From: | "Eric Turkheimer" <ent3c@virginia.edu> |
| Date: | Tue, 19 Dec 2006 09:14:55 -0500 |
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I have a matrix with three columns. I would like to compute the covariance between the first two, separately according to values of the third. The best I can figure out is to split the matrix up into a list using split(), and then use sapply(). I was wondering if there was a more direct way. A little more generally, how can you use tapply to evaluate bivariate functions?
Thanks, Eric -- Eric Turkheimer, PhD Department of Psychology University of Virginia PO Box 400400 Charlottesville, VA 22904-4400 434-982-4732 434-982-4766 (FAX) |
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