Python: keep only letters in string

Python: keep only letters in string

You can remove all non-letter characters from a string in Python using regular expressions or a list comprehension. Here are two common ways to achieve this:

  • Using Regular Expressions:
import re input_string = "Hello123, World!456" letters_only = re.sub(r'[^a-zA-Z]', '', input_string) print(letters_only) # Output: HelloWorld

In this example, the regular expression r'[^a-zA-Z]' matches any character that is not an uppercase or lowercase letter, and re.sub() is used to replace those characters with an empty string.

  • Using List Comprehension:
input_string = "Hello123, World!456" letters_only = ''.join([char for char in input_string if char.isalpha()]) print(letters_only) # Output: HelloWorld

Here, a list comprehension iterates through each character in the input string, and the char.isalpha() method is used to check if the character is a letter.

Both approaches will give you a string containing only the letters from the input string. Choose the one that fits your coding style and preferences.

Examples

  1. How to Remove Non-Alphabetic Characters from a String in Python Description: Learn how to retain only alphabetic characters from a given string using regular expressions.

    import re s = "Hello, World! 123" letters_only = re.sub(r'[^a-zA-Z]', '', s) # Remove all non-letters print(letters_only) # Output: HelloWorld

  2. Keeping Only Letters from a String in Python Description: Shows how to keep only letters from a given string using list comprehension and str.isalpha().

    s = "Python3.9 is awesome!" letters_only = ''.join([c for c in s if c.isalpha()]) # Keep only letters print(letters_only) # Output: Pythonisawesome

  3. Extracting Alphabetic Characters from a String in Python Description: Demonstrates how to extract alphabetic characters from a string using regular expressions.

    import re s = "123 ABC! def?" letters = re.findall(r'[a-zA-Z]', s) # Extract letters only result = ''.join(letters) # Join into a single string print(result) # Output: ABCdef

  4. Using str.isalpha() to Keep Only Letters in a String Description: Shows how to use the isalpha() method to create a string with only letters.

    s = "Learn123 with! Python@" letters_only = ''.join([char for char in s if char.isalpha()]) # Keep only letters print(letters_only) # Output: LearnwithPython

  5. Removing Non-Letter Characters from a String in Python Description: Learn how to remove non-letter characters from a string, keeping only alphabetic characters.

    s = "Hello123! Pythonista :)" letters_only = ''.join(filter(str.isalpha, s)) # Use filter to keep only letters print(letters_only) # Output: HelloPythonista

  6. Keeping Only Uppercase and Lowercase Letters in Python Description: This code snippet demonstrates how to retain only uppercase and lowercase letters from a string.

    import re s = "ABC123 def456" letters_only = re.sub(r'[^a-zA-Z]', '', s) # Keep only uppercase and lowercase letters print(letters_only) # Output: ABCdef

  7. Extracting Letters from a String in Python Description: Illustrates how to extract only letters from a given string using a simple loop.

    s = "Welcome! To Python3.9" letters = [char for char in s if char.isalpha()] # Extract letters letters_only = ''.join(letters) # Join into a string print(letters_only) # Output: WelcomeToPython

  8. Converting a String to Keep Only Letters in Python Description: Shows how to use a list comprehension to convert a string to keep only alphabetic characters.

    s = "Hi, Python 3.9!" letters_only = ''.join([c for c in s if c.isalpha()]) # Retain only letters print(letters_only) # Output: HiPython

  9. Keep Only Letters with str.isalpha() in Python Description: This example demonstrates how to use the isalpha() method to keep only letters from a string.

    s = "2024-April-Report" letters_only = ''.join([char for char in s if char.isalpha()]) # Keep only letters print(letters_only) # Output: AprilReport

  10. Extracting Letters from a String Using a Custom Function in Python Description: This snippet shows how to define a custom function to extract only letters from a given string.

    def extract_letters(s): return ''.join([char for char in s if char.isalpha()]) # Keep only letters s = "Test123! Another#Test" letters_only = extract_letters(s) # Extract only alphabetic characters print(letters_only) # Output: TestAnotherTest

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