R help - Jun 2014 - detect escape character

Dear All,

I should be knowing this, but not get it right... For a string like this:

"Man\Woman"

I would like to detect the escape character "\" and replace it with
"/".

Tried various ways using gsub(), but don't get it right yet. Any suggestion
would be highly welcomed...

Thank you,
Adrian

-- 
Adrian Dusa
University of Bucharest
Romanian Social Data Archive
1, Schitu Magureanu Bd.
050025 Bucharest sector 5
Romania
Tel.:+40 21 3126618 \
        +40 21 3120210 / int.101
Fax: +40 21 3158391

	[[alternative HTML version deleted]]

Hi,

R uses \ as a metacharacter, so you need a non-intuitive number of \:


mystring <- "Man\\Woman"
# \\ is a metacharacter and a \, so it's equivalent to \ in normal text
sub("\\\\", "/", mystring)


Sarah


On Tue, Jun 3, 2014 at 2:03 PM, Adrian Du?a <dusa.adrian at unibuc.ro>
wrote:
> Dear All,
>
> I should be knowing this, but not get it right... For a string like this:
>
> "Man\Woman"
>
> I would like to detect the escape character "\" and replace it
with "/".
>
> Tried various ways using gsub(), but don't get it right yet. Any
suggestion
> would be highly welcomed...
>
> Thank you,
> Adrian
>
-- 
Sarah Goslee
http://www.functionaldiversity.org

On Jun 3, 2014, at 11:03 AM, Adrian Du?a wrote:
> Dear All,
> 
> I should be knowing this, but not get it right...
I'm a little surprised to see you ask this, too, but we each have lacunae in
our R knowledge, so I hope this helps:
> s <- scan(what="")  # Assuming you were asking about items
coming in from ASCII data files
1: Man\Woman
2: 
Read 1 item
> s
[1] "Man\\Woman"
> gsub("\\", "/", s)
Error in gsub("\\", "/", s) : 
  invalid regular expression '\', reason 'Trailing backslash'
> gsub("\\\\", "/", s)
[1] "Man/Woman"

_Each_ of the backslashes in what you might have thought would succeed
("\\") also needed their own backslash. The first doubled backslash
becomes a real "escape"-character in the pattern and the second
doubled backslash becomes an ordinary ASCII backslash character.

-- 
David.
> For a string like this:
> 
> "Man\Woman"
> 
> I would like to detect the escape character "\" and replace it
with "/".
> 
> Tried various ways using gsub(), but don't get it right yet. Any
suggestion
> would be highly welcomed...
> 
> Thank you,
> Adrian
> 
> -- 
> Adrian Dusa
> University of Bucharest
> Romanian Social Data Archive
> 1, Schitu Magureanu Bd.
> 050025 Bucharest sector 5
> Romania
> Tel.:+40 21 3126618 \
>        +40 21 3120210 / int.101
> Fax: +40 21 3158391
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
David Winsemius
Alameda, CA, USA