There are & and | operators in the R language. There is an | operator in regular expressions. There is NOT any & operator in regular expressions. grep("ConfoMap&GuineaPigs", mydata, value=TRUE) looks for elements of mydata containing the literal string 'ConfoMap&GuineaPigs'.
> foo <- c("a","b","cab","back") > foo[grepl("a",foo) & grepl("b",foo)] [1] "cab" "back" grepl returns a TRUE/FALSE vector. On Thu, 20 Aug 2020 at 02:53, Ivan Calandra <calan...@rgzm.de> wrote: > Dear useRs, > > I feel really stupid, but I cannot understand why "&" doesn't work as I > expect, while "|" does. > > I have the following vector: > mydata <- c("SSFA-ConfoMap_GuineaPigs_NMPfilled.csv", > "SSFA-ConfoMap_Lithics_NMPfilled.csv", > "SSFA-ConfoMap_Sheeps_NMPfilled.csv", "SSFA-Toothfrax_GuineaPigs.xlsx", > "SSFA-Toothfrax_Lithics.xlsx", "SSFA-Toothfrax_Sheeps.xlsx") > and I want to find the values that include both "ConfoMap" and > "GuineaPigs". > > If I do: > grep("ConfoMap&GuineaPigs", mydata, value=TRUE) > it returns an empty vector, character(0). > > But if I do: > grep("ConfoMap|GuineaPigs", mydata, value=TRUE) > it returns all the elements that include either "ConfoMap" or > "GuineaPigs", as I would expect. > > So what is wrong with my "&" construct? How can I return the elements > that include both parts? > > Thank you for your help! > Ivan > > -- > Dr. Ivan Calandra > TraCEr, laboratory for Traceology and Controlled Experiments > MONREPOS Archaeological Research Centre and > Museum for Human Behavioural Evolution > Schloss Monrepos > 56567 Neuwied, Germany > +49 (0) 2631 9772-243 > https://www.researchgate.net/profile/Ivan_Calandra > > ______________________________________________ > 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. > [[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.