Hi, First post here. Grateful for any help you can give. I have data which looks like this:
id time x 1 12:01 5 1 12:02 14 1 12:03 6 1 12:04 3 2 12:01 98 2 12:02 23 2 12:03 1 2 12:04 4 3 12:01 5 3 12:02 65 3 12:03 23 3 12:04 23 But I want to add a column which is the cumulative sum of X, but only by id. I've used cumsum before, but not in this way. So the result should be something like: id time x cumsum 1 12:01 5 5 1 12:02 14 19 1 12:03 6 25 1 12:04 3 28 2 12:01 98 98 2 12:02 23 121 2 12:03 1 122 2 12:04 4 126 3 12:01 5 5 3 12:02 65 70 3 12:03 23 93 3 12:04 23 116 Any ideas please? -- View this message in context: http://r.789695.n4.nabble.com/Using-cumsum-with-group-by-tp4650457.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.
