pufftissue pufftissue <pufftissue <at> gmail.com> writes: > > What I am getting is indeed: > > 7200 23955 34563 8934 > 16.39977 10.03896 11.234 14.02 > > I'd like the final output to be: > > subject_id hr_Stand_Deviation > 7200 16.39977 > 23955 10.03896 > 34563 11.234 > 8934 14.02 >
The hard way could go like that; I personally got used to it, but I admit it is one of the thinks that are unusually difficult in R. dat = data.frame(SUBJECT_ID=sample(letters[1:5],100,TRUE),HR=rnorm(100)) sd.list = with(dat, tapply(HR, SUBJECT_ID, sd)) data.frame(SUBJECT_ID=rownames(sd.list),sd=sd.list) I think Hadley Wickham tried to make life easier with the plyr package, so I thought something like the below would work out of the box. However, there must be something wrong with the syntax, the result is only "approximately" correct. Dieter library(plyr) daply(dat,.(SUBJECT_ID),sd) ddply(dat,.(SUBJECT_ID),sd) ______________________________________________ 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.
