Hi Ari,

Try this instead

with(foo, tapply(V2, trust, mean, na.rm = TRUE))

See ?tapply and ?with for more information.

HTH,
Jorge


On Wed, Aug 24, 2011 at 2:51 PM, amalka <> wrote:

> Hello,
>
> I am a new user of R, and I'd be grateful if someone could help me with the
> following:
>
> I would like to compute the mean of variable "trust" in dataframe "foo",
> but
> separately for each level of variable V2.  That is, I'd like to compute the
> mean of trust at each level of V2.
>
> I have done this:
>
> > tmp <- by(foo, foo$V2, function(x) mean(foo$trust, na.rm=T))
> >tmp
>
> Doing this does indeed give me a mean for variable trust at each level of
> V2
> - but the problem is that I get the exact same mean for each level of V2.
> The means are not the really the same across levels of V2, but instead of
> getting the mean for each level of V2 I get the overall mean for the
> variable in the dataframe listed over and over for each level of V2.
>
> I have been attempting to figure this out for a while now, but I just can't
> seem to figure it out.
>
> Thanks for your time!
> Ari
>
> --
> View this message in context:
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> Sent from the R help mailing list archive at Nabble.com.
>
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