You could use lapply indeed of sapply: irisf[,index] <- lapply(irisf[,index], as.factor) str(irisf)
On Wed, Sep 9, 2009 at 8:06 AM, Petr PIKAL <petr.pi...@precheza.cz> wrote: > Dear all > > I have a simple problem which I thought is easy to solve but what I tried > did not work. I want to change character variables to factor in data > frame. It goes easily from factor to character, but I am stuck in how to > do backwards conversion. > > Here is an example > > irisf<-iris > irisf[,2]<-factor(irisf[,2]) # create second factor > > str(irisf) > 'data.frame': 150 obs. of 5 variables: > $ Sepal.Length: num 5.1 4.9 4.7 4.6 5 5.4 4.6 5 4.4 4.9 ... > $ Sepal.Width : Factor w/ 23 levels "2","2.2","2.3",..: 15 10 12 11 16 19 > 14 14 9 11 ... > $ Petal.Length: num 1.4 1.4 1.3 1.5 1.4 1.7 1.4 1.5 1.4 1.5 ... > $ Petal.Width : num 0.2 0.2 0.2 0.2 0.2 0.4 0.3 0.2 0.2 0.1 ... > $ Species : Factor w/ 3 levels "setosa","versicolor",..: 1 1 1 1 1 1 > 1 1 1 1 ... > index<-sapply(irisf, is.factor) > irisf[,index]<-sapply(irisf[,index], as.character) > > str(irisf) > 'data.frame': 150 obs. of 5 variables: > $ Sepal.Length: num 5.1 4.9 4.7 4.6 5 5.4 4.6 5 4.4 4.9 ... > $ Sepal.Width : chr "3.5" "3" "3.2" "3.1" ... > $ Petal.Length: num 1.4 1.4 1.3 1.5 1.4 1.7 1.4 1.5 1.4 1.5 ... > $ Petal.Width : num 0.2 0.2 0.2 0.2 0.2 0.4 0.3 0.2 0.2 0.1 ... > $ Species : chr "setosa" "setosa" "setosa" "setosa" ... > > I hoped that backwards conversion would be strightforward but... > > irisf[,index]<-sapply(irisf[,index], as.factor) > str(irisf) > 'data.frame': 150 obs. of 5 variables: > $ Sepal.Length: num 5.1 4.9 4.7 4.6 5 5.4 4.6 5 4.4 4.9 ... > $ Sepal.Width : chr "3.5" "3" "3.2" "3.1" ... > $ Petal.Length: num 1.4 1.4 1.3 1.5 1.4 1.7 1.4 1.5 1.4 1.5 ... > $ Petal.Width : num 0.2 0.2 0.2 0.2 0.2 0.4 0.3 0.2 0.2 0.1 ... > $ Species : chr "setosa" "setosa" "setosa" "setosa" ... > > I want to get both ch columns converted to factor but sapply produces > character variables (which is documented as it produces matrix or vector) > > > R.Version() > $platform > [1] "i386-pc-mingw32" > > $arch > [1] "i386" > > $os > [1] "mingw32" > > $system > [1] "i386, mingw32" > > $status > [1] "Under development (unstable)" > > $major > [1] "2" > > $minor > [1] "10.0" > > $year > [1] "2009" > > $month > [1] "07" > > $day > [1] "15" > > $`svn rev` > [1] "48932" > > $language > [1] "R" > > $version.string > [1] "R version 2.10.0 Under development (unstable) (2009-07-15 r48932)" > > Regards > Petr > > ______________________________________________ > 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. > -- Henrique Dallazuanna Curitiba-Paraná-Brasil 25° 25' 40" S 49° 16' 22" O [[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.
