[R] vector-factor operation

[Murray Jorgensen]

I found myself wanting to average a vector [vec] within each level of a 
factor [Fac], returning a vector of the same length as vec. After a 
while I realised that

lm1 <- lm(vec ~ Fac)
fitted(lm1)

did what I want.

But there must be another way to do this, and it would be good to be 
able to apply other functions than mean() in this way.

Cheers, Murray
-- 
Dr Murray Jorgensen      http://www.stats.waikato.ac.nz/Staff/maj.html
Department of Statistics, University of Waikato, Hamilton, New Zealand
Email: maj at waikato.ac.nz                                Fax 7 838 4155
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