Date: Wed, 17 Jan 2001 04:04:31 -0800 (PST) From: Samir Mishra <sqmishra at excite.com> Thanks in advance for any help I can get on this. I'm trying to change variable names between 2 systems - R and old SPSS, Oracle. I'm using the grep() and gsub() commands but I'm getting the following result -
test.dat <- c("a", "b.c", "d.e.f", "p_q,r")
test.dat
[1] "a" "b.c" "d.e.f" "p_q,r"
grep(",", test.dat, value = TRUE, extended = FALSE)
[1] "p_q,r"
grep("_", test.dat, value = TRUE, extended = FALSE)
[1] "p_q,r"
#NOT WHAT I WANT, I EXPECT TO GET ONLY ELEMENTS 2 & 3 RETURNED
grep(".", test.dat, value = TRUE, extended = FALSE)
[1] "a" "b.c" "d.e.f" "p_q,r"
Try
grep("\\.", test.dat, value = TRUE)
[1] "b.c" "d.e.f"
And similarly, with gsub(), I get -
gsub(",", "_", test.dat, extended = FALSE)
[1] "a" "b.c" "d.e.f" "p_q_r"
gsub("_", ".", test.dat, extended = FALSE)
[1] "a" "b.c" "d.e.f" "p.q,r"
#NOT WHAT I WANT
gsub(".", "_", test.dat, extended = FALSE) #NOT WHAT I WANT
[1] "_" "___" "_____" "_____"
But
gsub("\\.", "_", test.dat, extended = FALSE)
[1] "a" "b_c" "d_e_f" "p_q,r"
Am I doing something wrong?
`.' is a special character in a regexp. You have to escape it by `\', and that needs to be escaped in R. Perhaps we need to say more on the help page, but I am reluctant to try to define the meaning of `regular expression' there ....
Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272860 (secr) Oxford OX1 3TG, UK Fax: +44 1865 272595 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._