[R] mApply instead of by ???

[Frank E Harrell Jr]

Marten Winter wrote:

Now that's a brief note.  mApply in the Hmisc package may have large 
speed advantages over by for large datasets.  Also look at the summarize 
function in Hmisc, which uses mApply.

-- 
Frank E Harrell Jr   Professor and Chair           School of Medicine
                      Department of Biostatistics   Vanderbilt University