Python Regular Expressions to implement string unescaping

>>> import re
>>> mystring = r"This is n a test r"
>>> p = re.compile( "\\(\S)" )
>>> p.sub( "\1", mystring )
'This is n a test r'
>>> p.sub( "\\\1", mystring )
'This is \n a test \r'
>>> p.sub( "\\1", mystring )
'This is \1 a test \1'

>>> mystring = r"This is n a test r"
>>> mystring.decode('string-escape')
'This is n a test r'
>>> print mystring.decode('string-escape')
This is
 a test
>>>

"\n" == r"n"

>>> import re
>>> mystring = r"This is \n a test \r"
>>> p = re.compile( r"[\][\](.)" )
>>> print p.sub( r"\1", mystring )
This is n a test r
>>>

>>> d = {'n':'n', 'r':'r', 'f':'f'}
>>> p = re.compile(r"[\]([nrfv])")
>>> print p.sub(lambda mo: d[mo.group(1)], mystring)
This is
 a test
>>>

This is \n a test \r

This is \n a test \r

This is n a test r

'This is \n a test \r'

This is n a test r

>>> mystring = r"This is n a test r"
>>> mystring
'This is \n a test \r'
>>> print mystring
This is n a test r

>>> mystring = r"This is n ridiculous"
>>> print mystring
This is n ridiculous
>>> p = re.compile( r"\(S)" )
>>> print p.sub( 'bloody', mystring )
This is bloody ridiculous
>>> print p.sub( r'1', mystring )
This is n ridiculous
>>> print p.sub( r'\1', mystring )
This is 1 ridiculous
>>> print p.sub( r'\1', mystring )
This is n ridiculous

This is
ridiculous