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: > http://r.789695.n4.nabble.com/help-with-by-command-tp3766285p3766285.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.