How do I modify a single character in a string, in Python? Something like:
a = "hello"
a[2] = "m"
'str' object does not support item assignment.
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possible duplicate of Change one character in a string in Python?Wolf– Wolf2015-03-02 13:54:18 +00:00Commented Mar 2, 2015 at 13:54
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4 Answers
Strings are immutable in Python. You can use a list of characters instead:
a = list("hello")
When you want to display the result use ''.join(a):
a[2] = 'm'
print ''.join(a)
Comments
In python, string are immutable. If you want to change a single character, you'll have to use slicing:
a = "hello"
a = a[:2] + "m" + a[3:]
3 Comments
Shane
I suppose this would cost more memory if it's a really big string since you have to join three other strings together to form a new string, right?
JoshD
Oh, yeah! If you need to do a whole bunch of these type of manipulations, it's best to use a list of characters. Unless you happen to already have a string and just happen to want to change one character. Even then, it's probably faster to create and modify a list.
Manoj Govindan
@Shane: See @detly's answer below for a simple example.
Try constructing a list from it. When you pass an iterable into a list constructor, it will turn it into a list (this is a bit of an oversimplification, but usually works).
a = list("hello")
a[2] = m
You can then join it back up with ''.join(a).
Comments
It's because strings in python are immutable.
