re.sub(pattern, repl, string, count=0, flags=0)

Return the string obtained by replacing the leftmost non-overlapping occurrences of pattern in string by the replacement repl. If the pattern isn’t found, string is returned unchanged. repl can be a string or a function; if it is a string, any backslash escapes in it are processed. That is, \n is converted to a single newline character, \r is converted to a carriage return, and so forth. Unknown escapes such as \j are left alone. Backreferences, such as \6, are replaced with the substring matched by group 6 in the pattern. For example:

>>> re.sub(r'def\s+([a-zA-Z_][a-zA-Z_0-9]*)\s*\(\s*\):',

... r'static PyObject*\npy_\1(void)\n{',

... 'def myfunc():')

'static PyObject*\npy_myfunc(void)\n{'

If repl is a function, it is called for every non-overlapping occurrence of pattern. The function takes a single match object argument, and returns the replacement string. For example:

>>> def dashrepl(matchobj):

... if matchobj.group(0) == '-': return ' '

... else: return '-'

>>> re.sub('-{1,2}', dashrepl, 'pro----gram-files')

'pro--gram files'

>>> re.sub(r'\sAND\s', ' & ', 'Baked Beans And Spam', flags=re.IGNORECASE)

'Baked Beans & Spam'

The pattern may be a string or an RE object.

The optional argument count is the maximum number of pattern occurrences to be replaced; count must be a non-negative integer. If omitted or zero, all occurrences will be replaced. Empty matches for the pattern are replaced only when not adjacent to a previous match, so sub('x*', '-', 'abc') returns '-a-b-c-'.

In addition to character escapes and backreferences as described above, \g<name> will use the substring matched by the group named name, as defined by the (?P<name>...) syntax. \g<number> uses the corresponding group number; \g<2> is therefore equivalent to \2, but isn’t ambiguous in a replacement such as \g<2>0. \20 would be interpreted as a reference to group 20, not a reference to group 2 followed by the literal character '0'. The backreference \g<0> substitutes in the entire substring matched by the RE.

Changed in version 2.7: Added the optional flags argument.

#!/usr/bin/python

# -*- coding: utf-8 -*-

import re;

def pythonReSubDemo():

"""

demo Pyton re.sub

"""

inputStr = "hello 123 world 456";

def _add111(matched):

intStr = matched.group("number"); #123

intValue = int(intStr);

addedValue = intValue + 111; #234

addedValueStr = str(addedValue);

return addedValueStr;

replacedStr = re.sub("(?P<number>\d+)", _add111, inputStr);

print "replacedStr=",replacedStr; #hello 234 world 567

###############################################################################

if __name__=="__main__":

pythonReSubDemo();

#!/usr/bin/python

# -*- coding: utf-8 -*-

import re;

def pythonReSubDemo():

"""

demo Pyton re.sub

"""

inputStr = "hello 123 world 456 nihao 789";

def _add111(matched):

intStr = matched.group("number"); #123

intValue = int(intStr);

addedValue = intValue + 111; #234

addedValueStr = str(addedValue);

return addedValueStr;

replacedStr = re.sub("(?P<number>\d+)", _add111, inputStr, 2);

print "replacedStr=",replacedStr; #hello 234 world 567 nihao 789

###############################################################################

if __name__=="__main__":

pythonReSubDemo();