On Thu, 2006-02-09 at 09:22 +0100, Christoph Buser wrote: > Dear Frederico > > From your example it is not clear to me what you like to obtain: > Please have a look on the slightly changed example here (I > changed two values to show a potentially undesired side effect of > your coding. > > > test <- data.frame(rbind(c(3,3,10,21,0), c(2,3,11,12,0), c(3,4,12,23,0), > c(3,5,13,24,0))) > names(test) <- c("x","y","p","d","su") > test > > >> x y p d su > >> 1 3 3 10 21 0 > >> 2 2 3 11 12 0 > >> 3 3 4 12 23 0 > >> 4 3 5 13 24 0 > > j <- 3 > test[test[,1] == j, 5] <- test[test[,1] == j,2] + test[test[,2] == j,1] > > >> > > Warning message: > >> longer object length > >> is not a multiple of shorter object length in: > >> test[test[, 1] == j, 2] + test[test[, 2] == j, 1] > > Your code example produces now a warning for the adapted > data frame "test", since one tries to add two vectors of length 2 > and 3, respectively. The result is based on recycling of the > smaller vector. In your example there was no warning since the > second column had only one entry. > The result with the adapted data frame is: > > test > >> x y p d su > >> 1 3 3 10 21 6 > >> 2 2 3 11 12 0 > >> 3 3 4 12 23 6 > >> 4 3 5 13 24 8 > > Is that kind of recycling desired in your application. Otherwise > you should be careful with the coding example above.
Recycling was and is integral part of my plan. Cheers, Federico -- Federico C. F. Calboli Department of Epidemiology and Public Health Imperial College, St Mary's Campus Norfolk Place, London W2 1PG Tel +44 (0)20 7594 1602 Fax (+44) 020 7594 3193 f.calboli [.a.t] imperial.ac.uk f.calboli [.a.t] gmail.com ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html