Carl: "Almost anything you can do in a for() loop can be done easier and
faster with vectorization.-- "

That is false: while this is certainly true for a great many basic
vectorized operations, it is certainly false for most other things --
simulations are a typical example. Note that __ply type operations in base
R, plyr , and other packages are (generally) _not_vectorized; they are
"disguised" loops. Explicit for() loops are often just as fast or even a
bit faster, though many of us prefer what we consider the more transparent
functional style code of the __ply's.

Cheers,
Bert

Bert Gunter
Genentech Nonclinical Biostatistics

Internal Contact Info:
Phone: 467-7374
Website:
http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm

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