Dear R-helpers,
I've been thinking about this for some time, maybe someone can help. I have a fairly large dataset with thousands of firms, call the a, b, c, etc.. such as [,1] [,2] [1,] "A" 0.5 [2,] "" 0.2 [3,] "" 0.3 [4,] "B" 0.1 [5,] "" 0.9 [6,] "C" 0.4 Or to put it differently two vectors such as y <- c("A", "", "", "B", "", "C") x <- c(0.5, 0.2, 0.3, 0.1, 0.9, 0.4) The empty lines "" always belong to the firm above. Now I want to collapse the dataset so that each firm (A,B, C, etc) has one line only, using summation. So what I would like is yNew <- c("A", "B", "C") xNew <- c(1, 1, 0.4) The problem I'm having is that each firm has a different number of entries for x, so some like C have just one and others have ten or more, so I have difficulty imagining how to use a loop in this case. I'd be greatful for any suggestions. Karina ______________________________________________ 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.