Here is a more elegant solution using the plyr package.
my.data <- expand.grid(Thesis = 1:3, Day = c(0, 14), Run = 1:10)
my.data$A <- rpois(nrow(my.data), 10)
my.data$B <- rpois(nrow(my.data), 10)
my.data$C <- rpois(nrow(my.data), 10)
library(plyr)
ddply(my.data, .(Thesis, Day), function(x){
Baseline <- unlist(x[1, c("A", "B", "C")])
data.frame(t(apply(x[-1, c("A", "B", "C")], 1, function(z){z -
Baseline})))
})
Best regards,
Thierry
----------------------------------------------------------------------------
ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek
team Biometrie & Kwaliteitszorg
Gaverstraat 4
9500 Geraardsbergen
Belgium
Research Institute for Nature and Forest
team Biometrics & Quality Assurance
Gaverstraat 4
9500 Geraardsbergen
Belgium
tel. + 32 54/436 185
thierry.onkel...@inbo.be
www.inbo.be
To call in the statistician after the experiment is done may be no more than
asking him to perform a post-mortem examination: he may be able to say what the
experiment died of.
~ Sir Ronald Aylmer Fisher
The plural of anecdote is not data.
~ Roger Brinner
The combination of some data and an aching desire for an answer does not ensure
that a reasonable answer can be extracted from a given body of data.
~ John Tukey
> -----Oorspronkelijk bericht-----
> Van: r-help-boun...@r-project.org
> [mailto:r-help-boun...@r-project.org] Namens K. Elo
> Verzonden: vrijdag 14 januari 2011 14:52
> Aan: r-help@r-project.org
> Onderwerp: Re: [R] test
>
> Dear Romezo,
>
> a solution maybe not that elegant and effective, but seems to work:
>
> test_calculate<-function() {
> tarrow<-1
> TARGET<-data.frame("Thesis"=0, "Day"=0,"A"=0,"B"=0,"C"=0)
> for (i in c(unique(my.data$Thesis))) {
> for (j in c(unique(my.data$Day[ my.data$Thesis==i ]))) {
> TEMPDF<-subset(my.data, Thesis==i & Day==j)
> for (k in c(1:(nrow(TEMPDF)-1))) {
> for (l in c((k+1):nrow(TEMPDF))) {
> TARGET[tarrow,]<-cbind(i,j,(TEMPDF[k,3]-TEMPDF[l,3]),
> (TEMPDF[k,4]-TEMPDF[l,4]), (TEMPDF[k,5]-TEMPDF[l,5]))
> tarrow<-tarrow+1
> }
> }
> }
> }
> print(TARGET)
> }
>
> (Please note: my.data is your original data frame)
>
> Kind regards,
> Kimmo
>
> ______________________________________________
> R-help@r-project.org mailing list
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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
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