[R] standardizing one variable by dividing each value by the mean - but within levels of a factor

[Dimitri Liakhovitski]

Hello!

I have a data frame with a factor and a numeric variable:

x<-data.frame(factor=c("b","b","d","d","e","e"),values=c(1,2,10,20,100,200))

For each level of "factor" - I would like to divide each value of
"values" by the mean of "values" that corresponds to the level of
"factor"
In other words, I would like to get a new variable that is equal to:
1/1.5
2/1.5
10/15
20/15
100/150
200/150

I realize I could do it through tapply starting with:
factor.level.means<-tapply(x$values,x$factor,mean) ... etc.


But it seems clunky to me.
Is there a more elegant way of doing it?

Thanks a lot!


-- 
Dimitri Liakhovitski