Hi, I'd like to divide each element of a matrix by a specific value per column. These specific values are stored in a list. For example:
> x <- c(1,2,3,4,5) > y <- matrix(c(1:30), nrow = 6) Now I want to divide each element in y[,1] by x[1], y[,2] by x[2] etc. I have tried this > my_function <- function(data, ind) data/ind > apply(y, 2, my_function, x) [,1] [,2] [,3] [,4] [,5] [1,] 1 7.0 13.0 19.0 25.0 [2,] 1 4.0 7.0 10.0 13.0 [3,] 1 3.0 5.0 7.0 9.0 [4,] 1 2.5 4.0 5.5 7.0 [5,] 1 2.2 3.4 4.6 5.8 [6,] 6 12.0 18.0 24.0 30.0 Warning messages: 1: In data/ind : longer object length is not a multiple of shorter object length 2: In data/ind : longer object length is not a multiple of shorter object length 3: In data/ind : longer object length is not a multiple of shorter object length 4: In data/ind : longer object length is not a multiple of shorter object length 5: In data/ind : longer object length is not a multiple of shorter object length but as you can see it is applying them by row rather than column. Any ideas how to do this? Is there a variable within 'apply' that can be used to determine which column of y is being processed? thanks for any help adam > sessionInfo() R version 2.11.1 (2010-05-31) x86_64-apple-darwin9.8.0 locale: [1] en_GB.UTF-8/en_GB.UTF-8/C/C/en_GB.UTF-8/en_GB.UTF-8 attached base packages: [1] stats graphics grDevices utils datasets methods base ______________________________________________ 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.