How do you replace all occurrences in a list in python?

Shubham Singh Kshatriya

Table of Contents Show

The replace() method
Return value
Explanation
The re.sub() method
Return value
Explanation
1. Using list.remove() function
2. Using List Comprehension
3. Using filter() function
How do you replace all items in a list Python?
How do you replace multiple values in a list Python?
How do I remove all occurrences of an element in a list?
How do you replace text in a list in Python?

Overview

In Python, we can replace all occurrences of a character in a string using the following methods:

replace()
re.sub()

The replace() method

replace() is a built-in method in Python that replaces all the occurrences of the old character with the new character.

Syntax

"".replace(oldCharacter, newCharacter, count)

Parameters

This method accepts the following parameters:

oldCharacter: This is the old character that will be replaced.
newCharacter: This is the new character that will replace the old character.
count: This is an optional parameter that specifies the number of times to replace the old character with the new character.

Return value

This method creates a copy of the original string, replaces all the occurrences of the old character with the new character, and returns it.

Example

string = "This is an example string"
# replace all the occurrences of "i" with "I"
result = string.replace("i", "I")
# print result
print(result)

Implementation of the replace() method

Explanation

Line 1: We declare a string.
Line 4: We use the replace() method to replace all the occurrences of i with I.
Line 7: We print the result to the console.

Output

In the output, we can see all the occurrences of i in the string are replaced with I.

The re.sub() method

We can also use regular expressions to replace all the occurrences of a character in a string. This can be done using re.sub() method.

Syntax

re.sub(oldCharacter, newCharacter, string)

Parameters

This method accepts the following parameters:

oldCharacter: This is the old character that will be replaced.
newCharacter: This is the new character that will replace the old character.
string: This is the string in which the characters are to be replaced.

Return value

This method creates a copy of the original string, replaces all the occurrences of the old character with the new character, and returns it.

Example

import re
string = "This is an example string"
# replace all the occurrences of "i" with "I"
result = re.sub("i", "I", string)
# print result
print(result)

Implementation of the re.sub() method

Explanation

Line 1: We import the re module.
Line 3: We declare a string.

Line 6: We use the re.sub() method to replace all the occurrences of i with I.
Line 9: We print the result to the console.

Output

In the output, we can see all the occurrences of i in the string are replaced with I.

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Shubham Singh Kshatriya

This post will discuss how to remove all occurrences of an item from a list in Python.

1. Using list.remove() function

list.remove(x) removes the first occurrence of value x from the list, but it fails to remove all occurrences of value x from the list.

if__name__=='__main__':

l =[0,1,0, 0,1,0,1, 1]

val=0

l.remove(val)

print(l) # prints [1, 0, 0, 1, 0, 1, 1]

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To remove all occurrences of an item from a list using list.remove(), you can take advantage of the fact that it raises a ValueError when it can’t find the specified item in the list. The idea is to repeatedly call remove() function until it raises a ValueError exception. This is demonstrated below:

if__name__=='__main__':

l =[0,1,0, 0,1,0,1, 1]

val=0

try:

whileTrue:

l.remove(val)

exceptValueError:

pass

print(l) # prints [1, 1, 1, 1]

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2. Using List Comprehension

The recommended solution is to use list comprehension. With list comprehensions, you can create a sublist of those elements that satisfy a certain condition. A list comprehension consists of an expression, followed by a for-loop, followed by an optional for-loop or if-statement enclosed within the square brackets [].

Here’s a working example using list comprehension, which is more concise and readable, and more Pythonic than the above code:

if__name__=='__main__':

l =[0,1,0, 0,1,0,1, 1]

val=0

# filter the list to exclude 0's

l=[iforiin lifi!=val]

print(l) # prints [1, 1, 1, 1]

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3. Using filter() function

You can also use the built-in function filter(function, iterable), which can construct an iterator from the list elements (an iterable) for which function returns true.

Note that filter(function, iterable) is equivalent to the generator expression (item for item in iterable if function(item)). This is demonstrated below:

if__name__=='__main__':

l =[0,1,0, 0,1,0,1, 1]

val=0

l =list(filter(lambdax:x !=val,l))

print(l) # prints [1, 1, 1, 1]

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That’s all about removing all occurrences of an item from a list in Python.

How do you replace all items in a list Python?

We can replace values inside the list using slicing. First, we find the index of variable that we want to replace and store it in variable 'i'. Then, we replace that item with a new value using list slicing.

How do you replace multiple values in a list Python?

One way that we can do this is by using a for loop. One of the key attributes of Python lists is that they can contain duplicate values. Because of this, we can loop over each item in the list and check its value. If the value is one we want to replace, then we replace it.

How do I remove all occurrences of an element in a list?

Use the remove() Function to Remove All the Instances of an Element From a List in Python. The remove() function only removes the first occurrence of the element. If you want to remove all the occurrence of an element using the remove() function, you can use a loop either for loop or while loop.

How do you replace text in a list in Python?

Replace a specific string in a list. If you want to replace the string of elements of a list, use the string method replace() for each element with the list comprehension. If there is no string to be replaced, applying replace() will not change it, so you don't need to select an element with if condition .