CODEWITHSUNDEEP
pythonregexpython-3.x
user6003691
user6003691

Reputation:

Function to dictate the replacements in re.sub method (Python)

Trying to use regex to perform substitutions on a string.

re.sub(regex, repl_func, content)

The problem is that I do not understand how the replacement will occur via the repl_func when I need the substitution to be dependent on the matching object from that regex; i.e. I will use that matched object as a dictionary key to get the matching value with which that particular object needs to be replaced.

    for mobj in re.finditer(regex, content):
        t = mobj.lastgroup
        v = match_obj.group(t)

        if t == 'NAME':
            ...
        elif t == '\n':
            ...

I have tried to iterate all the matching objects, as seen above, but cannot figure out how to apply the re.sub. If I understand correctly, the repl_function in my first code segment needs to somehow know which is the matched object from that regex.

Any ideas, especially using code will be much appreciated cause I am only just now starting with Python.

Upvotes: 2

Views: 1440

Answers (2)

Kasravnd
Kasravnd

Reputation: 107347

The re.sub() function passes the matched object to repl_function as an argument and replaces the returned result from that function with the matched string. If you want to replace the matched object with a particular string in a dictionary you can simply use a function to handle that:

def repl_func(matched_obj):
    my_dict = {'NAME':'rep1', '\n':'rep2'}
    try:
        match = matched_obj.group(0)
    except AttributeError:
        matched = ''
        # Or raise an exception
    else:
        return my_dict.get(match, '')

re.sub(regex, repl_func, content)

Upvotes: 2

Marc J
Marc J

Reputation: 1433

The re docs are pretty clear on this one:

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 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.

Upvotes: 1

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