On Apr 25, 2012, at 10:57 AM, Carly Huitema wrote:
Hello R-help list, I would really appreciate help with my factoring problem. My generated data is this: df <- expand.grid(T=seq(10,80, by=5), conc=rep(c(1, 3, 7), 2)) df$curve <- as.factor(rep(1:6, each=length(seq(10,80, by=5))))
df$counts <- 3*df$T/df$conc + rnorm(df$T,0,2) plot(counts~T, df) What I would like to do add a new column to the dataframe of zeroed data (say df$counts.zeroed). For each curve (designated by factor df$curve) I want to take the value in counts and subtract the minimum value for that curve.
translated to R that request would be something along these minimally tested lines:
df$counts.zeroed <- with( df, ave(counts, curve, FUN=function(x){ x- min(x) }) )
However, I don't really have an idea of how to approach this problem and haven't found anything in my searches. And just as a second question, my second line of code assigns the factors, but if there is a nicer way of doing this I would really appreciate knowing how.
There is a `gl` function that I think creates grouping factors, but I generally use `rep` because I understand it better.
Thanks for any help! Carly ______________________________________________ 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.
David Winsemius, MD West Hartford, CT ______________________________________________ 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.
