Hi
sorry I did not read your reply as thoroughly. But generally matrices are
quite often exchanged for data frames. Also if you have list with mixture
of numeric and nonumeric data such approach results in nonumeric output as
matrix can have values only of one type. I would therefore generally
prefer
> dd=do.call('data.frame',aa)
> dd
AA BB
c1 113.0000 123.00
c2 76.0000 5.00
c3 0.8945 1.00
c4 0.8850 0.99
> t(dd)
c1 c2 c3 c4
AA 113 76 0.8945 0.885
BB 123 5 1.0000 0.990
approach
Regards
Petr
r-help-boun...@r-project.org napsal dne 29.04.2010 08:44:10:
> 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]]
>
> ______________________________________________
> 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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