Try using aggregate: aggregate(tb[-1], list(tb$Subject), FUN=median, na.rm = T)
On Tue, Jun 10, 2008 at 10:18 AM, Michal Figurski < [EMAIL PROTECTED]> wrote: > Hello everyone, > > I am new to R, I have been using SAS for a while. Not surprisingly, I find > R much better in graphics, which is publication ready right away. > > Recently, I have been trying to calculate some basic statistics using R. I > have a dataset of multiple rows per subject. For example: > > Subject Date Factor1 Factor2 Factor3 > P1 0.5 1 1 3 > P1 1 3 2 5 > P1 2 3 5 NA > ... > P2 0.5 1 6 4 > P2 1 2 NA 7 > P2 2 3 1 2 > ... > > I wanted to get the 'by subject' statistics of the factors. I used the > following code: a=by(dat1, dat1$Subject, mean, na.rm=TRUE) - this is for a > mean. > However, when I try that with a 'median', I get an error message. It is > strange to me, because with the 'summary' option, I get the median values > for all factors separately, among other information. What I need is just a > median, because I later need it for plotting. > I have read old posts on the archive, and I agree that the action of > 'median' is according to the documentation. However, I think this is a > serious inconvenience, and it should be changed to work in the same way as > mean, summary or sd options. > > Nevertheless, accepting the reality, I have a question to all: how to > obtain the by-subject medians of factors in such dataset? > > Thanks in advance, > > -- > Michal J. Figurski > HUP, Pathology & Laboratory Medicine > Xenobiotics Toxicokinetics Research Laboratory > 3400 Spruce St. 7 Maloney > Philadelphia, PA 19104 > > ______________________________________________ > 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.
