On Aug 12, 2010, at 2:11 PM, Toby Gass wrote: > Dear helpeRs, > > I have a dataframe (14947 x 27) containing measurements collected > every 5 seconds at several different sampling locations. If one > measurement at a given location is less than zero on a given day, I > would like to delete all measurements from that location on that day. > > Here is a toy example: > > toy <- data.frame(CH = rep(3:5,3), DAY = c(rep(4,5), rep(5,4)), > SLOPE = c(seq(0.2,0.6, .1),seq(0.2, -0.1, -0.1))) > > In this example, row 9 has a negative measurement for Chamber 5, so I > would like to delete row 6, which is the same Chamber on the same > day, but not row 3, which is the same chamber on a different day. In > the full dataframe, there are, of course, many more days. > > Is there a handy R way to do this? > > Thank you for the assistance. > > Toby
Not fully tested, but here is one possibility: > toy CH DAY SLOPE 1 3 4 0.2 2 4 4 0.3 3 5 4 0.4 4 3 4 0.5 5 4 4 0.6 6 5 5 0.2 7 3 5 0.1 8 4 5 0.0 9 5 5 -0.1 > subset(toy, ave(SLOPE, CH, DAY, FUN = function(x) any(x < 0)) == 0) CH DAY SLOPE 1 3 4 0.2 2 4 4 0.3 3 5 4 0.4 4 3 4 0.5 5 4 4 0.6 7 3 5 0.1 8 4 5 0.0 See ?ave and ?subset HTH, Marc Schwartz ______________________________________________ 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.
