How Can I Sort Strings with Embedded Numbers Naturally in Python?

Natural Sorting: The Art of Arranging Strings with Embedded Numbers

Sorting strings with numbers can be a tricky task, but it's essential for many applications. In this Q&A, we'll explore a solution that achieves human-like sorting results, allowing you to arrange strings like "something1", "something2", and "something17" in a logical order.

The Challenge:

The given input consists of a list of strings containing numbers. However, the default sort() method fails to arrange them in a way that makes sense to humans. For instance, the following list:

something1
something12
something17
something2
something25
something29

would be sorted as:

something1
something12
something17
something2
something25
something29

The Solution: Natural Keys

The solution lies in using natural keys, a sorting method designed for human readability. Natural keys treat numbers within strings as separate entities while maintaining the overall structure of the string.

Here's a Python implementation using the natural_keys function:

import re

def natural_keys(text):
    return [int(c) if c.isdigit() else c for c in re.split(r'(\d+)', text)]

When applied to the input list, the result would be:

['something1', 'something2', 'something12', 'something17', 'something25', 'something29']

Additional Considerations:

If you need to sort strings with floating-point numbers, you can modify the regex in the natural_keys function to match floats instead of integers.

def natural_keys(text):
    return [float(c) if c.isdigit() or '.' in c else c for c in re.split(r'[+-]?([0-9]+(?:[.][0-9]*)?|[.][0-9]+)', text)]

This enhancement enables you to sort strings like:

something1
something2
something1.0
something1.25
something1.105

in the following order:

['something1', 'something1.0', 'something1.105', 'something1.25', 'something2']

By embracing the power of natural keys, you can now effortlessly arrange strings with embedded numbers in a human-readable manner, making your data manipulation tasks more efficient and intuitive.

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