Hi split/sapply can be used besides other options
sapply(split(iris[,1:4], iris$Species), mean) Regards Petr r-help-boun...@r-project.org napsal dne 10.06.2010 00:43:29: > Hi there: > I have a question about generating mean value of a data.frame. Take > iris data for example, if I have a data.frame looking like the following: > --------------------- > Sepal.Length Sepal.Width Petal.Length Petal.Width Species > 1 5.1 3.5 1.4 > 0.2 setosa > 2 4.9 3.0 1.4 > 0.2 setosa > 3 4.7 3.2 1.3 > 0.2 setosa > . . . . > . . > . . . . > . . > . . . . > . . > ----------------------- > There are three different species in this table. I want to make a table and > calculate mean value for each specie as the following table: > > ----------------- > Sepal.Length Sepal.Width Petal.Length > Petal.Width > mean.setosa 5.006 3.428 1.462 > 0.246 > mean.versicolor 5.936 2.770 4.260 > 1.326 > mean.virginica 6.588 2.974 5.552 > 2.026 > ----------------- > Is there any short syntax can do it?? I mean shorter than the code I wrote > as following: > > attach(iris) > mean.setosa<-mean(iris[Species=="setosa", 1:4]) > mean.versicolor<-mean(iris[Species=="versicolor", 1:4]) > mean.virginica<-mean(iris[Species=="virginica", 1:4]) > data.mean<-rbind(mean.setosa, mean.versicolor, mean.virginica) > detach(iris) > ------------------ > > Thanks a million!!! > > > -- > ===================================== > Shih-Hsiung, Chou > System Administrator / PH.D Student at > Department of Industrial Manufacturing > and Systems Engineering > Kansas State University > > [[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. ______________________________________________ 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.
