similar function to php's str_replace in python?

Question

is there a similar function in python that takes search(array) and replace(array) as a parameter? Then takes a value from each array and uses them to do search and replace on subject(string).

I know I can achieve this using for loops, but just looking more elegant way.

Answer 1

I believe the answer is no.

I would specify your search/replace strings in a list, and the iterate over it:

edits = [(search0, replace0), (search1, replace1), (search2, replace2)] # etc.
for search, replace in edits:
    s = s.replace(search, replace)

Even if python did have a str_replace-style function, I think I would still separate out my search/replace strings as a list, so really this is only taking one extra line of code.

Finally, this is a programming language after all. If it doesn't supply the function you want, you can always define it yourself.

Answer 2

Do it with regexps:

import re

def replace_from_list(replacements, str):
    def escape_string_to_regex(str):
        return re.sub(r"([\\.^$*+?{}[\]|\(\)])", r"\\\1", str)

    def get_replacement(match):
        return replacements[match.group(0)]

    replacements = dict(replacements)
    replace_from = [escape_string_to_regex(r) for r in replacements.keys()]
    regex = "|".join(["(%s)" % r for r in replace_from])
    repl = re.compile(regex)

    return repl.sub(get_replacement, str)

# Simple replacement:
assert replace_from_list([("in1", "out1")], "in1") == "out1"

# Replacements are never themselves replaced, even if later search strings match
# earlier destination strings:
assert replace_from_list([("1", "2"), ("2", "3")], "123") == "233"

# These are plain strings, not regexps:
assert replace_from_list([("...", "out")], "abc ...") == "abc out"

Using regexps for this makes the searching fast. This won't iteratively replace replacements with further replacements, which is usually what's wanted.

Answer 3

Heh - you could use the one-liner below whose elegance is second only to its convenience :-P

(Acts like PHP when search is longer than replace, too, if I read that correctly in the PHP docs.):

** Edit: This new version works for all sized substrings to replace. **

>>> subject = "Coming up with these convoluted things can be very addictive."
>>> search = ['Coming', 'with', 'things', 'addictive.', ' up', ' these', 'convoluted ', ' very']
>>> replace = ['Making', 'Python', 'one-liners', 'fun!']
>>> reduce(lambda s, p: s.replace(p[0],p[1]),[subject]+zip(search, replace+['']*(len(search)-len(replace))))
'Making Python one-liners can be fun!'