[R] how to assign a group mean to individual cases?

Gabor Grothendieck ggrothendieck at gmail.com
Tue Nov 13 01:01:48 CET 2007

Look at:


On Nov 12, 2007 5:01 PM, Casey Klofstad <klofstad at gmail.com> wrote:
> I need advice on how to create a variable that is the group mean of
> another variable.
> For example, I have a variable called x for which each row in the data
> set has a value. I also have a nominal variable called g that
> indicates which of 100 different groups each row belongs to.
> So, I want to create a new variable called w, which is the group mean
> of x for which ever group the row belongs to (as indicated by variable
> g). Ideally, I'd also like to take out each row's value of x before
> calculating the group mean assigned to that row.
> I've already tried the aggregate command. That gives me the group
> means, but does not allow me to assign them to each row in the data
> set.
> --
> Casey A. Klofstad
> University of Miami
> Department of Political Science
> Coral Gables, FL
> klofstad at gmail.com
> http://moya.bus.miami.edu/~cklofstad
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