Thanks again, Dennis and Petr!
The solution using the plyr package was perfect:
ddply(data, .(id, mod1), summarize, es = mean(es), mod2 = head(mod2, 1))
Take care,
AC
On Thu, Jan 28, 2010 at 11:26 PM, Petr PIKAL <petr.pi...@precheza.cz> wrote:
> Hi
>
> r-help-boun...@r-project.org napsal dne 28.01.2010 17:40:01:
>
> > Thank you, Dennis and Petr.
> >
> > One more question: when aggregating to one es per id, how would I go
> about
> > keeping the other variables in the data.frame (e.g., keeping the value
> for
> > the first row of the other variables, such as mod2) e.g.:
> >
> > # Dennis provided this example (notice how mod2 is removed from the
> output):
> >
> > > with(x, aggregate(list(es = es), by = list(id = id, mod1 = mod1),
> mean))
> > id mod1 es
> > 1 3 1 0.20
> > 2 1 2 0.30
> > 3 2 4 0.15
> >
> > # How can I get this output (taking the first row of the other variable
> in
> > the data.frame):
>
> If I remember it correctly in my suggestion I used something like
>
> aggregate(x[,-columns.mod1 and mod2], by = x[, columns.mod1 and mod2,
> mean)
>
> Which shall use mod2 as aggregating variable.
>
> Does it result in output you wanted?
>
> Regards
> Petr
>
>
> >
> > id es mod1 mod2
> >
> > 1 .30 2 wai
> > 2 .15 4 other
> > 3 .20 1 itas
> >
> >
> > Thank you,
> >
> > AC
> >
> >
> > On Thu, Jan 28, 2010 at 1:29 AM, Petr PIKAL <petr.pi...@precheza.cz>
> wrote:
> >
> > > HI
> > >
> > > r-help-boun...@r-project.org napsal dne 28.01.2010 04:35:29:
> > >
> > > > > Hi All,
> > > > >
> > > > > I'm conducting a meta-analysis and have taken a data.frame with
> > > multiple
> > > > > rows per
> > > > > study (for each effect size) and performed a weighted average of
> > > effect
> > > > > size for
> > > > > each study. This results in a reduced # of rows. I am particularly
> > > > > interested in
> > > > > simply reducing the additional variables in the data.frame to the
> > > first row
> > > > > of the
> > > > > corresponding id variable. For example:
> > > > >
> > > > > id<-c(1,2,2,3,3,3)
> > > > > es<-c(.3,.1,.3,.1,.2,.3)
> > > > > mod1<-c(2,4,4,1,1,1)
> > > > > mod2<-c("wai","other","calpas","wai","itas","other")
> > > > > data<-as.data.frame(cbind(id,es,mod1,mod2))
> > >
> > > Do not use cbind. Its output is a matrix and in this case character
> > > matrix. Resulting data frame will consist from factors as you can
> check by
> > >
> > >
> > > str(data)
> > >
> > > data<-data.frame(id=id,es=es,mod1=mod1,mod2=mod2)
> > >
> > >
> > > > >
> > > > > data
> > > > >
> > > > > id es mod1 mod2
> > > > > 1 1 0.3 2 wai
> > > > > 2 2 0.1 4 other
> > > > > 3 2 0.2 4 calpas
> > > > > 4 3 0.1 1 itas
> > > > > 5 3 0.2 1 wai
> > > > > 6 3 0.3 1 wai
> > > > >
> > > > > # I would like to reduce the entire data.frame like this:
> > >
> > > E.g. aggregate
> > >
> > > aggregate(data[, -(3:4)], data[,3:4], mean)
> > > mod1 mod2 id es
> > > 1 4 calpas 2 0.3
> > > 2 1 itas 3 0.2
> > > 3 1 other 3 0.3
> > > 4 4 other 2 0.1
> > > 5 1 wai 3 0.1
> > > 6 2 wai 1 0.3
> > >
> > > doBy or tapply or ddply from plyr library or ....
> > >
> > > Regards
> > > Petr
> > >
> > > > >
> > > > > id es mod1 mod2
> > > > >
> > > > > 1 .30 2 wai
> > > > > 2 .15 4 other
> > > > > 3 .20 1 itas
> > > > >
> > > > > # If possible, I would also like the option of this (collapsing on
> id
> > > and
> > > > > mod2):
> > > > >
> > > > > id es mod1 mod2
> > > > > 1 .30 2 wai
> > > > > 2 0.1 4 other
> > > > > 2 0.2 4 calpas
> > > > > 3 0.1 1 itas
> > > > > 3 0.25 1 wai
> > > > >
> > > > > Any help is much appreciated!
> > > > >
> > > > > AC Del Re
> > > > >
> > > >
> > > > [[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.
> > >
> > >
> >
> > [[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.
>
>
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