[R] How do I get sub to insert a single backslash?

2006-01-05 Thread Michael Dewey 
Something about the way R processes backslashes is defeating me.
Perhaps this is because I have only just started using R for text processing.

I would like to change occurrences of the ampersand  into ampersand 
preceded by a backslash.

  temp - R  D
  sub(, \, temp)
[1] R  D
  sub(, \\, temp)
[1] R  D
  sub(, \\\, temp)
[1] R  D
  sub(, , temp)
[1] R \\ D
 

So I can get zero, or two backslashes, but not one. I am sure this is 
really simple but I did not find the answer by doing, for example ?regexp 
or ?Quotes


Michael Dewey
http://www.aghmed.fsnet.co.uk

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Re: [R] How do I get sub to insert a single backslash?

2006-01-05 Thread Peter Dalgaard 
Michael Dewey [EMAIL PROTECTED] writes:

 Something about the way R processes backslashes is defeating me.
 Perhaps this is because I have only just started using R for text processing.
 
 I would like to change occurrences of the ampersand  into ampersand 
 preceded by a backslash.
 
   temp - R  D
   sub(, \, temp)
 [1] R  D
   sub(, \\, temp)
 [1] R  D
   sub(, \\\, temp)
 [1] R  D
   sub(, , temp)
 [1] R \\ D
  
 
 So I can get zero, or two backslashes, but not one. I am sure this is 
 really simple but I did not find the answer by doing, for example ?regexp 
 or ?Quotes


None of those result strings  have two backslashes!


Hint:

 nchar(R \\ D)
[1] 6

and ?Quotes tellse the entire story.

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