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1. Finn Årup Nielsen Python

   re.sub('o', '\\', 'ooo') Second argument in !Python re.sub function should be r'ed else an error. Why!?

   Friday, 19-Mar-10 17:46:02 UTC from web at Marburg, Hesse, Germany
   • Philippe Gauthier

     @fnielsen: the string '\\' means really '\', which is not a valid regular expression escape sequence (use r'\\' or '\\\\')

     Friday, 19-Mar-10 17:50:41 UTC
   • Finn Årup Nielsen Philippe Gauthier

     @deuxpi Yes, I know. But to me it doesn't make sense that the 2nd argument (the replacement) should be a regular expression...

     Friday, 19-Mar-10 18:06:04 UTC
   • Philippe Gauthier

     @fnielsen: Perhaps you want to use "ooo".replace("o", "\\") then?

     Friday, 19-Mar-10 18:26:08 UTC
   • Marc Rintsch

     @fnielsen 2nd argument is not a re but can contain references to groups in the re, e.g.: re.sub('(.)(.)', r'\2\1', 'ab') → 'ba'

     Friday, 19-Mar-10 18:35:58 UTC
   • Radomir Dopieralski

     @fnielsen r'\' == '\\', r'\\' == '\\\\', and the second argument still needs backslashes escaped (because you can use thngs like \1 in it).

     Friday, 19-Mar-10 20:00:36 UTC
   • pepijndevos

     @fnielsen \\ would result in a single backslash, if you want just a backslash, you'll need four of them.

     Friday, 19-Mar-10 20:05:43 UTC
   • Guy K. Kloss

     @fnielsen '\' is an escape character. e. g. '\n' is a new line, However, r'\n' are two characters, the backslash and the n

     Friday, 19-Mar-10 20:53:53 UTC
   • Finn Årup Nielsen Marc Rintsch

     @bj Ahhh. Now I see. With \1 it makes sense to have the second argument handle backslashes.

     Saturday, 20-Mar-10 10:34:55 UTC