This isn't going to be the most elegant, but it should work: ## Get the factors as characters
ff <- as.character(chemdata$site) ## Identify those that match what you want ff <- grepl(ff, "BC-") now use this logical vector to subset chemdata[ff, ] Can't test, but should be good to go assuming that "BC-" entirely identifies those sites you want. If you have other "BC-" things read through the ?regex documentation and I think it describes how to do selective wildcards Michael On Tue, Oct 4, 2011 at 2:39 PM, Rich Shepard <rshep...@appl-ecosys.com> wrote: > I have a data frame called chemdata with this structure: > >> str(chemdata) > > 'data.frame': 14886 obs. of 4 variables: > $ site : Factor w/ 148 levels "BC-0.5","BC-1",..: 104 145 126 115 114 > 128 124 2 3 3 ... > $ sampdate: Date, format: "1996-12-27" "1996-08-22" ... > $ param : Factor w/ 8 levels "As","Ca","Cl",..: 1 1 1 1 1 1 1 1 1 1 ... > $ quant : num 0.06 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 ... > > I've looked in the R Cookbook and Dalgaard's intro book without finding a > way to use wildcards (e.g., like "BC-*") or explicitly witing each site ID > when subdsetting a data frame.. > > I need to create subsets (as data frames) based on sites, but including > all sites on each stream. For example, using the initial site factor shown > above, I want a subset containing all data for sites "BC-0.5", "BC-1". > "BC-2", "BC-3", "BC-4", "BC-5", and "BC-6". > > Pointers appreciated, > > Rich > > ______________________________________________ > 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. > ______________________________________________ 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.
