More concisely, ddply(Orange, .(Tree), transform, scaled = scale(age))
HTH, baptiste On 4 October 2011 11:24, <john.morrongie...@csiro.au> wrote: > That works a treat Thierry, thanks! I wasn't aware of the plyr package but I > like what it does- I'll put it to use work in the future. > > Regards > > John > > -----Original Message----- > From: ONKELINX, Thierry [mailto:thierry.onkel...@inbo.be] > Sent: Monday, 3 October 2011 6:36 PM > To: Morrongiello, John (CMAR, Hobart); r-help@r-project.org > Subject: RE: [R] new standardised variable based on group membership > > Dear John, > > You need to combine scale with a grouping function. > > data(Orange) > library(plyr) > Orange <- ddply(Orange, .(Tree), function(x){ > x$ddplyAge <- scale(x$age)[, 1] > x > }) > > Orange$aveAge <- ave(Orange$age, by = Orange$Tree, FUN = scale) > > all.equal(Orange$ddplyAge, Orange$aveAge) > > Best regards, > > Thierry > > >> -----Oorspronkelijk bericht----- >> Van: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] >> Namens john.morrongie...@csiro.au >> Verzonden: maandag 3 oktober 2011 7:34 >> Aan: r-help@r-project.org >> Onderwerp: [R] new standardised variable based on group membership >> >> Hi >> I have a data comprised of repeated measures of growth (5-15 records per >> individual) for 580 fish (similar to Orange dataset from nlme library). I >> would like >> to standardise these growth measures (yi – ŷ/sd) using mean and standard >> deviation unique to each fish. Can someone suggest a function that would help >> me do this? I’ve had a look at scale and sweep but can’t find a worked >> example >> that does what I’m after >> >> Cheers >> >> John >> >> >> [[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.
