Why isn't this Python replace function working?

Question

I'm trying to remove a set of characters from a larger string. Here's what I've tried:

string = 'aabc'
remove = 'ac'
for i in remove:
    string.replace(i, '', 1)
print(string)

I keep getting back my original string when I run this. The variable i is getting the characters 'a' and then 'c'. The replace function works for me if i do string.replace('a', '', 1). Why isn't this working or is there a simpler way to do this?

help(str.replace) --> _Return a copy of string S with all occurrences of substring old replaced by new. If the optional argument count is given, only the first count occurrences are replaced._ — tdelaney, Nov 13 '14 at 18:28

score 5 · Accepted Answer · answered Nov 13 '14 at 18:25

5

Strings are immutable in python, so string.replace() does not mutate the string; it returns a new string with the replacements.

Try this:

string = string.replace(i, '', 1)

answered Nov 13 '14 at 18:25

gcarvelli

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score 2 · Answer 2 · edited Nov 13 '14 at 18:26

2

replace returns a new string.

Strings in python are immutable.

As such, you must assign the return value:

string_new = "ABCD".replace("A","Z")

edited Nov 13 '14 at 18:26

ApproachingDarknessFish

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answered Nov 13 '14 at 18:24

Joran Beasley

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score 1 · Answer 3 · answered Nov 13 '14 at 18:26

1

A new string will be generated as Strings are immutable...

Try this -

string = 'aabc'
remove = 'ac'
for i in remove:
    result = string.replace(i, '', 1)
print(result)

answered Nov 13 '14 at 18:26

user1050619

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score 0 · Answer 4 · answered Nov 13 '14 at 18:28

0

As Strings are immutable you cant use replace with just string.replace(). As a better way use set :

>>> s='aabcc'
>>> s=''.join(set(s))
'acb'

answered Nov 13 '14 at 18:28

Mazdak

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Why isn't this Python replace function working?

4 Answers4