Hi all, I apologize for this probably stupid question, but I really can't figure it out. I have a dataframe like this:
group <- c(rep('A', 8), rep('B', 15), rep('C', 6)) time <- c(rep(seq(1:4), 2), rep(seq(1:5), 3), rep(seq(1:3), 2)) value <- runif (29, 1, 10) dfx <- data.frame (group, time, value) I want to calculate mean and standard deviation for all values that belong to the same group and the same time and end up with a dataframe with the columns time, group, mean and sd that contains the calculated values for every group at every time point only once (12). What is the most elegant way to do this? Oh, and I would like to avoid renaming columns (like the _X1/_X2 created by casting with multiple functions), if possible. I am sure that this is pretty basic, but I have already wasted a ridiculous amount of time on this. Thanks, Kai [[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.