Python String Replace
2 min read
In this article, we will talk about how to replace a substring inside a string in Python, using the
In Python, strings are represented as immutable
str objects. The
str class comes with many methods that allow you to manipulate strings.
.replace() method takes the following syntax:
str.replace(old, new[, maxreplace])
str- The string you are working with.
old– The substring you want to replace.
new– The substring that replaces the old substring.
maxreplace– Optional argument. The number of matches of the old substring you want to replace. The matches are counted from the beginning of the string.
The method returns a copy of the string
srt with some or all matches of substring
old replaced by
maxreplace is not given, all occurrences are be replaced.
In the example below we're replacing the substring
far in string
s = 'A long time ago in a galaxy far, far away.'
The result is a new string:
'A long time ago in a galaxy miles, miles away.'
When the optional
maxreplace argument is given, it will limit the number of replaced matches. In the following example we're replacing only the first occurrence:
s = 'My ally is the Force, and a powerful ally it is.'
s.replace('ally', 'friend', 1)
The result string will look like this:
'My friend is the Force, and a powerful ally it is.'
To delete a substring, use an empty string
'' as a replacement. For example to remove
space from the following string you would use:
s = 'That’s no moon. It’s a space station.'
s.replace('space ', '')
The new string will look like the following:
`That’s no moon. It’s a station.'
Replace Substring in List of Strings
To replace a substring in a list of strings, use the list comprehension construct as show below:
s.replace('old', 'new') for s in list
Let's take a look at the following example:
names = ['Anna Grace', 'Betty Grace', 'Emma Grace']
new_names = [s.replace('Grace', 'Lee') for s in names]
The code above creates a copy of the list with all occurrences of substring
Grace replaced by
['Anna Lee', 'Betty Lee', 'Emma Lee']
Replacing a substring in a string is one of the most basic operations when writing code in Python. After reading this tutorial, you should have a good understanding of how to use the
If you have any questions or feedback, feel free to leave a comment.