Hi Martin, On Fri, Jan 20, 2012 at 12:04 PM, Martin Batholdy <[email protected]> wrote: > Hi, > > > I am currently trying to z-transform (that is subtracting the mean and divide > by the standard deviation) multiple columns of a data.frame at the same time. > > > My first approach was: > > x <- data.frame(c(0:10), c(10:20)) > (x - colMeans(x)) / apply(x, 2, sd) > > > This is obviously not working. > > Is there a convenient way to z-transform each column separately (so in this > case, each column represents an independent variable that should be > z-transformed)
The `scale` function essentially does this except it divides by the sample standard deviation. Punch `scale.default` into your R session to see the code if you want to see how one way you could write the code yourself. HTH, -steve -- Steve Lianoglou Graduate Student: Computational Systems Biology | Memorial Sloan-Kettering Cancer Center | Weill Medical College of Cornell University Contact Info: http://cbio.mskcc.org/~lianos/contact ______________________________________________ [email protected] 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.
