Find and Replace Values in List in Python

You can find and replace string values in a list using a list comprehension or map() function in Python.

Method 1: list comprehension

new_list = [s.replace('old_string', 'new_string') for s in input_list]

Method 2: map() function

new_list =  map(lambda s: str.replace(s, 'old_string', 'new_string'), input_list)

The following examples demonstrate how to use list comprehension and map() functions to replace string values in a list in Python.

Example 1: find and replace string using list comprehension

Create a sample list,

input_list = ['country', 'city', 'village', 'county']

If you want to replace a specific string in the above list, you can use the list comprehension method.

For example, if you want to replace the village string with the city string, you can use the list comprehension method as below.

new_list = [s.replace('village', 'city') for s in input_list]
print(new_list)

# output
['country', 'city', 'city', 'county']

In the above code, list comprehension is used to iterate over each item in the input list and replace the string using the replace() function when there is a match.

In addition to string replacement, you can also use list comprehension to replace the characters in the string.

input_list = ['country;', 'city;', 'village', 'county']

# replace semicolon(;) with colon (:)
new_list = [s.replace(';', ':') for s in input_list]

print(new_list)

# output
['country:', 'city:', 'village', 'county']

Example 2: find and replace string using map()

Create a sample list,

input_list = ['country', 'city', 'village', 'county']

If you want to replace a specific string in the above list, you can use the map() function.

For example, if you want to replace the village string with the city string, you can use the map() function as below.

new_list =  list(map(lambda s: str.replace(s, 'village', 'city'), input_list))
print(new_list)

# output
['country', 'city', 'city', 'county']

In the above code, the lambda function checks if each item in the list matches to village and replaces it with the city string. Additionally, the list() function is used to convert the map object into a list.