How to Efficiently Strip Non-Alphanumeric Characters in Python?

Stripping Non-Alphanumeric Characters in Python

In Python, removing non-alphanumeric characters from a string requires a slightly different approach compared to PHP.

Pythonic Methods

For a truly "Pythonic" solution, consider the following methods:

• Join Alphanumeric Characters: Use a list comprehension to iterate over the characters in the string and join only the alphanumeric ones.
• Filter Alphanumeric: Use the filter() function and str.isalnum() to filter out non-alphanumeric characters.

Alternative Approaches

For performance considerations, other methods may be faster:

• Regex Substitution with [W_] : Compile a regular expression ([W_] ) to match and substitute all non-alphanumeric characters.
• **Regex Substitution with pattern.sub(): For repeated substitution, precompile the regular expression using re.compile() and then use pattern.sub().

Performance Benchmarking

Here are timing results for various methods, using the string.printable string:

Method	Time (μs/loop)
Join alphanumeric	57.6
Filter alphanumeric	37.9
Regex substitution with [W_]	27.5
Regex substitution with [W_]	15
Regex substitution with pattern.sub()	11.2

The timings show that using the precompiled regular expression with pattern.sub() is the fastest method.

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