[R] Data.frame manipulation

[Petr PIKAL]

Hi

r-help-bounces at 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.pikal at precheza.cz> 
wrote:
> 
> > HI
> >
> > r-help-bounces at 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 at 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 at r-project.org mailing list
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http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.