Dear R-helpers.
Can someone kindly tell me how to replace a single forward slash with double backward slash in a string? i.e., from "a/b" to "a\\b" Many thanks in advance. -Sean [[alternative HTML version deleted]] ______________________________________________ [hidden email] 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. |
On Dec 13, 2009, at 1:00 PM, Sean Zhang wrote: > Dear R-helpers. > > Can someone kindly tell me how to replace a single forward slash > with double > backward slash in a string? > > i.e., from "a/b" to "a\\b" > sub("/", "\\\\","a/b") #the backslashes need to be doubled because they are the escape character. [1] "a\\b" > > Many thanks in advance. > > -Sean > > [[alternative HTML version deleted]] > > ______________________________________________ > [hidden email] 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. David Winsemius, MD Heritage Laboratories West Hartford, CT ______________________________________________ [hidden email] 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. |
David Winsemius wrote:
> > On Dec 13, 2009, at 1:00 PM, Sean Zhang wrote: > >> Dear R-helpers. >> >> Can someone kindly tell me how to replace a single forward slash with >> double >> backward slash in a string? >> >> i.e., from "a/b" to "a\\b" > > > sub("/", "\\\\","a/b") > #the backslashes need to be doubled because they are the escape character. > [1] "a\\b" Bzzzt. Wrong answer. > nchar(sub("/", "\\\\","a/b") ) [1] 3 > cat(sub("/", "\\\\","a/b"),"\n") a\b > nchar(sub("/", "\\\\\\\\","a/b") ) [1] 4 > sub("/", "\\\\\\\\","a/b") [1] "a\\\\b" > cat(sub("/", "\\\\\\\\","a/b"),"\n") a\\b You are not the first... ;-) -- O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - ([hidden email]) FAX: (+45) 35327907 ______________________________________________ [hidden email] 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. |
Peter Dalgaard wrote:
> David Winsemius wrote: >> >> On Dec 13, 2009, at 1:00 PM, Sean Zhang wrote: >> >>> Dear R-helpers. >>> >>> Can someone kindly tell me how to replace a single forward slash with >>> double >>> backward slash in a string? >>> >>> i.e., from "a/b" to "a\\b" >> >> > sub("/", "\\\\","a/b") >> #the backslashes need to be doubled because they are the escape >> character. >> [1] "a\\b" > > Bzzzt. Wrong answer. ... unless of course, Sean really intended to replace a single slash with a SINGLE backslash. > > > nchar(sub("/", "\\\\","a/b") ) > [1] 3 > > cat(sub("/", "\\\\","a/b"),"\n") > a\b > > > nchar(sub("/", "\\\\\\\\","a/b") ) > [1] 4 > > sub("/", "\\\\\\\\","a/b") > [1] "a\\\\b" > > cat(sub("/", "\\\\\\\\","a/b"),"\n") > a\\b > > You are not the first... ;-) > -- O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - ([hidden email]) FAX: (+45) 35327907 ______________________________________________ [hidden email] 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. |
In reply to this post by Peter Dalgaard
On Dec 13, 2009, at 1:58 PM, Peter Dalgaard wrote: > David Winsemius wrote: >> On Dec 13, 2009, at 1:00 PM, Sean Zhang wrote: >>> Dear R-helpers. >>> >>> Can someone kindly tell me how to replace a single forward slash >>> with double >>> backward slash in a string? >>> >>> i.e., from "a/b" to "a\\b" >> > sub("/", "\\\\","a/b") >> #the backslashes need to be doubled because they are the escape >> character. >> [1] "a\\b" > > Bzzzt. Wrong answer. > > > nchar(sub("/", "\\\\","a/b") ) > [1] 3 > > cat(sub("/", "\\\\","a/b"),"\n") > a\b > > > nchar(sub("/", "\\\\\\\\","a/b") ) > [1] 4 > > sub("/", "\\\\\\\\","a/b") > [1] "a\\\\b" > > cat(sub("/", "\\\\\\\\","a/b"),"\n") > a\\b > > You are not the first... ;-) Thanks. I'm probably not the last, but seeing as this is not my first effort at this either, let me make an effort toward preventing myself (and Zhang) from getting it wrong (again). -- The console display is a potentially misleading representation of the string object in the sense that it displays any "\" characters as "\\"? -- When used in a regular expression, one needs to use FOUR "\"'s to get one 'internal' "\", the first two "\\" create one escape-char within the parser then which then applies to the second escape-char created by the second two "\\"? (I think I have seen both those facts in print before, but perhaps typing them will make it stick this time.) > > -- > O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B > c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K > (*) \(*) -- University of Copenhagen Denmark Ph: (+45) > 35327918 > ~~~~~~~~~~ - ([hidden email]) FAX: (+45) > 35327907 David Winsemius, MD Heritage Laboratories West Hartford, CT ______________________________________________ [hidden email] 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. |
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