How to only accept letters in python

In this tutorial, we will look at how to keep only letters (extract alphabets) from a string in Python with the help of examples.

How to extract only alphabets from a string in Python?

You can use a regular expression to extract only letters (alphabets) from a string in Python. You can also iterate over the characters in a string and using the string isalpha() function to keep only letters in a string.

Let’s look at both the methods with the help of examples –

Extract alphabets from a string using regex

You can use the regular expression 'r[^a-zA-Z]' to match with non-alphabet characters in the string and replace them with an empty string using the re.sub() function. The resulting string will contain only letters.

Let’s look at an example.

import re

# string with letters, numbers, and special characters
s = "[email protected]"
# keep only letters
res = re.sub(r'[^a-zA-Z]', '', s)
print(res)

Output:

BuckyBarnes

You can see that the resulting string contains only letters.

Using string isalpha() function

Alternatively, you can use the string isalpha() function to remove non-alphabet characters from the string. Use the following steps –

1. Create an empty string to store our result string with only letters.
2. Iterate through each character in our given string.
3. For each character, check if its an alphabet using the string isalpha() function. If it is, then add the character to our result string.

Let’s look at an example.

# string with letters, numbers, and special characters
s = "[email protected]"
# keep only letters
res = ""
for ch in s:
    if ch.isalpha():
        res += ch
print(res)

Output:

BuckyBarnes

The result string contains only letters from the original string.

The above code can be reduced to fewer lines using list comprehension.

# string with letters, numbers, and special characters
s = "[email protected]"
# keep only letters
res = "".join([ch for ch in s if ch.isalpha()])
print(res)

Output:

BuckyBarnes

We get the same result as above.

You might also be interested in –

• Python – Check If String Contains Only Letters
• Python – Remove Non Alphanumeric Characters from String
• Remove Substring From a String in Python

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• Piyush is a data scientist passionate about using data to understand things better and make informed decisions. In the past, he's worked as a Data Scientist for ZS and holds an engineering degree from IIT Roorkee. His hobbies include watching cricket, reading, and working on side projects.

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