Great, Thanks. Now I have many options. Steven from iPhone
> On Feb 13, 2023, at 10:52 AM, Andrew Simmons <akwsi...@gmail.com> wrote: > > What I meant is that that > > mydata[, !grepl("^yr", colnames(mydata)), drop = FALSE] > > and > > mydata[!grepl("^yr", colnames(mydata))] > > should be identical. Some people would prefer the first because the > indexing looks the same as matrix indexing, whereas some people would > prefer the second because it is more efficient. However, I would argue > it is exactly as efficient. You can see from the first few lines of > `[.data.frame` when the first index is missing and the second is > provided, it does almost the same thing as if only the first index > provided. > >> On Sun, Feb 12, 2023 at 9:38 PM Steven Yen <st...@ntu.edu.tw> wrote: >> >> x[“V2”] would retain columns of x headed by V2. What I need is the >> opposite——I need a data grime with those columns excluded. >> >> Steven from iPhone >> >> On Feb 13, 2023, at 9:33 AM, Rolf Turner <r.tur...@auckland.ac.nz> wrote: >> >> >> On Sun, 12 Feb 2023 14:57:36 -0800 >> Jeff Newmiller <jdnew...@dcn.davis.ca.us> wrote: >> >> x["V2"] >> >> >> is more efficient than using drop=FALSE, and perfectly normal syntax >> >> (data frames are lists of columns). >> >> >> <SNIP> >> [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.