Hi: One (of many) ways is to use the aggregate() function in base R:
df <- data.frame(g = rep(LETTERS[1:5], each = 5), y = rnorm(25)) aggregate(y ~ g, data = df, FUN = sum) g y 1 A -1.3165949 2 B 1.9850015 3 C -0.6460323 4 D -1.6459293 5 E 6.7001807 HTH, Dennis On Sun, Feb 13, 2011 at 8:32 PM, Jonathan Salerno <jdsale...@ucdavis.edu>wrote: > This is a seemingly simple problem, but I'm unable to make any progress. I > have a large dataset, within it there is a column of location names, some > of > which repeat; the adjacent column lists values for each location name. I > need to sum the values which correspond to the same location name, > returning > a matrix of the columns containing the location name and the corresponding > sum of values. Thanks very much for any assistance. > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. > [[alternative HTML version deleted]] ______________________________________________ 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.
