multicore by(), like mclapply?
On Tue, Oct 11, 2011 at 7:54 AM, ivo welch <ivo.welch at gmail.com> wrote:
hi josh---thx. ?I had a different version of this, and discarded it because I think it was very slow. ?the reason is that on each application, your version has to scan my (very long) data vector. ?(I have many thousand different cases, too.) ?I presume that by() has one scan through the vector that makes all splits.
by.data.frame() is basically a wrapper for tapply(), and the key line in tapply() is ans <- lapply(split(X, group), FUN, ...) which should be easy to adapt for mclapply.
Thomas Lumley Professor of Biostatistics University of Auckland