You're right. I don't use regexps in R very much. In most other languages, a single \ is needed. The R parser is different and I forgot. Thanks for the heads up.
On Tue, Oct 14, 2014 at 10:01 AM, Ivan Calandra <ivan.calan...@univ-reims.fr> wrote: > Shouldn't it be > grep("\\.at$",colnames(df)) > with double back slash? > > Ivan > > -- > Ivan Calandra > University of Reims Champagne-Ardenne > GEGENA² - EA 3795 > CREA - 2 esplanade Roland Garros > 51100 Reims, France > +33(0)3 26 77 36 89 > ivan.calan...@univ-reims.fr > https://www.researchgate.net/profile/Ivan_Calandra > > Le 14/10/14 16:38, John McKown a écrit : >> >> On Tue, Oct 14, 2014 at 9:23 AM, Kate Ignatius <kate.ignat...@gmail.com> >> wrote: >>> >>> I'm having an issue with grep: >>> >>> I have numerous columns that end with .at... when I use grep like so: >>> >>> df[,grep(".at",colnames(df))] >>> >>> it works fine. When I have one column that ends with .at, it does not >>> work. Why is that? As this is loop with varying number of columns >>> ending in .at I would like some code that would work with 1 to n >>> number of columns. >>> >>> Is there something more optimal than grep? >>> >>> Thanks! >> >> I can't answer your direct question. But do you realize that your code >> does not match your words? The grep show does not _only_ match columns >> who name end with the characters '.at'. It matches all column names >> which contain any character followed by the characters "at". To do the >> match with only columns whose names end with the characters ".at", you >> need: grep("\.at$",colnames(df)). >> >> You might want to post an example which fails. Just to be complete, be >> sure to use the dput() function so that it is easy for members of the >> group to cut'n'paste to get your data into our own R workspace. >> > > ______________________________________________ > 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. -- There is nothing more pleasant than traveling and meeting new people! Genghis Khan Maranatha! <>< John McKown ______________________________________________ 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.