On Aug 12, 2010, at 2:24 PM, Marc Schwartz wrote: > 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
This can actually be slightly shortened to: > subset(toy, !ave(SLOPE, CH, DAY, FUN = function(x) any(x < 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 HTH, Marc ______________________________________________ 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.
