How Can I Sort Strings Containing Embedded Numbers and Floats Naturally?

Sorting Strings with Embedded Numbers

Sorting lists of strings containing numbers can pose a challenge due to the varying data types. The following approach provides a solution for correctly sorting these strings.

To preprocess the strings, we define a helper function, atoi(), which converts a string to an integer if it represents a number; otherwise, it returns the original string. This aids in extracting numerical components from strings.

Next, we introduce the natural_keys() function, which splits the strings using regular expressions and applies the atoi() function to each component. This transforms the list into a sortable form.

Using the sort() method, we apply the natural_keys() function as the key argument. This sorts the list in human order, considering both alphabetical and numerical components.

Example:

Consider the following list of strings:

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

Sorting this list with the natural_keys() function produces:

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

Sorting Text with Floats:

To extend the functionality to include floats, the regular expression pattern in natural_keys() can be modified to match floating-point numbers.

return [ atof(c) for c in re.split(r'[+-]?([0-9]+(?:[.][0-9]*)?|[.][0-9]+)', text) ]

where atof() is a helper function that attempts to convert the string to a float.

This allows for the sorting of strings containing both alphabetic and floating-point components.

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