I do not understand what you want. If aps is constant
over each class then the mean for each class is equal
to any value of aps.
Using your example you can do
tapply(icu1$aps, icu1$d, mean)
but it does not give you anything new. Can you
explain the problem a bit more?
--- sigalit mangut-leiba <[EMAIL PROTECTED]> wrote:
> hello,
> i want to compute the mean of a variable ("aps") for
> every class
> (1,2, and 3).
> every id have a few obs., "aps" and class are
> constant over id.
> like this:
> id aps class
> 1 11 2
> 1 11 2
> 1 11 2
> 1 11 2
> 1 11 2
> 2 8 3
> 2 8 3
> 2 8 3
> 3 12 2
> 3 12 2
> .
> .
>
> i tried:
>
> tapply(icu1$aps_st, icu1$hidclass, function(z)
> mean(unique(z)))
>
> but it's counting every row and not every id.
>
> thank you,
>
> Sigalit.
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