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.