Hi,
Thanks, actually I mentioned in the reply, you need to turn the matrix into
data frame in the end if use this method. e.g
>
df=data.frame(name=c('AA','BB','AA'),c1=c(23,123,203),c2=c(54,5,98),c3=c(0.999,1,0.79),c4=c(0.78,0.99,0.99))
> aa=by(df[,2:5],df$name,mean)
> dd=do.call('rbind',aa)
> df=data.frame(dd)
> df
c1 c2 c3 c4
AA 113 76 0.8945 0.885
BB 123 5 1.0000 0.990
Regards
Tengfei
On Thu, Apr 29, 2010 at 1:30 AM, Petr PIKAL <petr.pi...@precheza.cz> wrote:
> Hi
>
> r-help-boun...@r-project.org napsal dne 29.04.2010 08:11:41:
>
> > Hi
> >
> > you could try
> >
> > do.call('rbind',aa)
>
> No, No, No. rbind and cbind binds vectors as rows or columns of
> ***matrix***, result is not a data frame
>
> do.call("rbind",aa)
> X069rutil X102anatas
> 105 26.9 7.9
> 200 22.8 10.6
> 400 30.6 13.3
> 600 50.8 20.6
> 800 78.7 NA
> exp.df<-do.call("rbind",aa)
> str(exp.df)
> num [1:5, 1:2] 26.9 22.8 30.6 50.8 78.7 7.9 10.6 13.3 20.6 NA
> - attr(*, "dimnames")=List of 2
> ..$ : chr [1:5] "105" "200" "400" "600" ...
> ..$ : chr [1:2] "X069rutil" "X102anatas"
>
> If some object has rectangular shape and has column names it does not
> automatically mean that it is data frame
>
> Regards
> Petr
>
>
> >
>
> >
> > then turn the matrix into data frame
> >
> > regards
> >
> > Tengfei
> >
> > On Wed, Apr 28, 2010 at 10:56 PM, Yuan Jian <jayuan2...@yahoo.com>
> wrote:
> >
> > > Hello,
> > >
> > > I have a data.frame:
> > > name col1 col2 col3 col4
> > > AA 23 54 0.999 0.78
> > > BB 123 5 1 0.99
> > > AA 203 98 0.79 0.99
> > >
> > > I want to get mean value data.frame in terms of name:
> > >
> > > name col1 col2 col3 col4
> > >
> > > AA 113.0000 76.0000 0.8945 0.8850
> > >
> > > BB 123.00 5.00 1.00 0.99
> > >
> > > I tried to use by function:
> > >
> > > >aa<-by(test[,2:5], feature, mean)
> > > I found aa is "by" function.
> > > > class(aa)
> > > [1] "by"
> > >
> > > how can I transfer aa to a data frame?
> > >
> > > thanks
> > > YU
> > >
> > >
> > >
> > >
> > >
> > >
> > > [[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.
> > >
> > >
> >
> >
> > --
> > Tengfei Yin
> > MCDB PhD student
> > 1620 Howe Hall, 2274,
> > Iowa State University
> > Ames, IA,50011-2274
> > Homepage: www.tengfei.name
> >
> > [[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.
>
>
--
Tengfei Yin
MCDB PhD student
1620 Howe Hall, 2274,
Iowa State University
Ames, IA,50011-2274
Homepage: www.tengfei.name
[[alternative HTML version deleted]]
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