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.