How to Sort Strings Containing Numbers Correctly?

How to Sort Strings with Numbers Properly

Sorting strings that contain numbers can be challenging. The default sort() method treats each character as its own entity, resulting in incorrect ordering. To correctly sort such strings, a more sophisticated approach is needed.

One effective method is human sorting, which utilizes regular expressions to extract the numerical components from the strings. This technique allows for the numbers to be sorted independently of the alphabetical portions.

To implement human sorting, follow these steps:

1. Import the re module.
2. Define a function atoi(text) to convert a string to an integer or leave it as a string if it's not a number.
3. Define a function natural_keys(text) to split the string using the regular expression (d ).
4. Sort the list using the key parameter of sort(), passing in the natural_keys function.

Example:

import re

def atoi(text):
    return int(text) if text.isdigit() else text

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

alist = [
    "something1",
    "something12",
    "something17",
    "something2",
    "something25",
    "something29"]

alist.sort(key=natural_keys)
print(alist)

Output:

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

This approach accurately sorts the strings by considering both the alphabetical and numerical portions.

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