[R] vector-factor operation
maj at stats.waikato.ac.nz
Fri Apr 14 07:46:12 CEST 2006
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)
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.
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
Phone +64 7 838 4773 wk Home +64 7 825 0441 Mobile 021 1395 862
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