I have a data frame with three columns, x, y, and a. I want to create a matrix from these values such that for matrix m: m[x,y] == a
Obviously, I can go row by row through the data frame and insert the value a at the correct x,y location in the matrix. I can make that slightly more efficient (perhaps), by doing something like this: > for (each.x in unique(df$x)) m[each.x, df$y[df$x == each.x]] <- df$a[df$x == > each.x] But I feel that there must be a more efficient, or at least more elegant way to do this. -- Gene ______________________________________________ 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.
