Hi Duncan,
I only know about sub() and gsub(). There is no way to have pattern be a regular expression and replacement be a fixed string. Backslash is the only special character in replacement. If you need a reference, see this file: https://github.com/wch/r-source/blob/04650eddd6d844963b6d7aac02bd8d13cbf440d4/src/main/grep.c particularly functions R_pcre_string_adj and wstring_adj. So just double the backslashes in replacement and you'll be good to go. On Thu, Apr 11, 2024, 12:36 Duncan Murdoch <murdoch.dun...@gmail.com> wrote: > I noticed this issue in stringr::str_replace, but it also affects sub() > in base R. > > If the pattern in a call to one of these needs to be a regular > expression, then backslashes in the replacement text are treated specially. > > For example, > > gsub("a|b", "\\", "abcdef") > > gives "def", not "\\\\def" as I wanted. To get the latter, I need to > escape the replacement backslashes, e.g. > > gsub("a|b", "\\\\", "abcdef") > > which gives "\\\\cdef". > > I have two questions: > > 1. Is there a variant on sub or str_replace which allows the pattern to > be declared as a regular expression, but the replacement to be declared > as fixed? > > 2. To get what I want, I can double the backslashes in the replacement > text. This would do that: > > replacement <- gsub("\\\\", "\\\\\\\\", replacement) > > Are there any other special characters to worry about besides backslashes? > > Duncan Murdoch > > ______________________________________________ > 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.
