[R] grouped colSums without for loops?

[Hans Ekbrand]

On Tue, Mar 18, 2008 at 05:57:59AM -0500, jim holtman wrote:
> Is this what you want?
> 
> > lapply(split(d, d$foo), function(x) colSums(x[,-1]))

Yes! Thank you! the *apply functions seem very powerful, thanks again
for giving me a hint on how to use them.

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