Remove All Occurrences of a Substring

Lecture 98:- Remove All Occurrences of a Substring

To remove all occurrences of a substring from a given string in Python, you can use various methods, but regular expressions (RE) can provide an elegant solution. The re.sub() function can be used to replace all occurrences of a specific pattern (substring) with an empty string.

Here's a Python code snippet to remove all occurrences of a substring using regular expressions:

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import re def remove_substring_with_re(input_string, substring):    # Use a regular expression to find all occurrences of the substring and replace them with an empty string    modified_string = re.sub(re.escape(substring), '', input_string)    return modified_string # Test the function input_string = "Hello, Hello, World!" substring_to_remove = "Hello, " result = remove_substring_with_re(input_string, substring_to_remove) print(result)

Output:

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World!

In this example, the re.sub() function takes the regular expression pattern to be replaced as the first argument. The re.escape(substring) is used to escape the substring properly, as it might contain characters that have special meanings in regular expressions. The second argument is the replacement, which is an empty string ''.

The re.sub() function then finds all occurrences of the substring in the input_string and replaces them with an empty string, effectively removing all occurrences of the specified substring.

Keep in mind that this method is case-sensitive. If you want a case-insensitive version, you can use the re.IGNORECASE flag as the third argument to re.sub():

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import re def remove_substring_case_insensitive(input_string, substring):    # Use a regular expression with the IGNORECASE flag to find all occurrences of the substring and replace them with an empty string    modified_string = re.sub(re.escape(substring), '', input_string, flags=re.IGNORECASE)    return modified_string # Test the function input_string = "Hello, HeLLo, World!" substring_to_remove = "hello, " result = remove_substring_case_insensitive(input_string, substring_to_remove) print(result)

Output:

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World!

Now, the function will remove all occurrences of "hello, " regardless of their case.