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Another idea would be
coef(lm(cbind(price, volume, yield) ~ as.factor(code) - 1,
mydat))
but
this is limited to the special case of the mean. Andy's idea is easier to
generalize.
One way or the other, the data need to be split into
groups. Here's one possible way:
sapply(split(mydata, mydata$code), colMeans)
Andy
A friend of mine has a data
set
With variables
:
code price volume
yield
where code is an integer and can
take on
say 20 different
values.
He wants the means of price,
volume, yield
But within each code
value.
Obviously, he can break it up by
each code and then
take the means but he was
hoping
there was a
quicker
way to do this ?
Thanks.
mark
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