How do I reliably compare version strings in Python?

Comparing Version Strings in Python

When working with directories containing multiple versions of the same software, it's crucial to identify and utilize only the latest version. This requires comparing version numbers, which can be challenging as string comparisons may not yield accurate results.

Package-Specific Comparisons

Python provides a standardized solution for comparing version strings using the packaging.version module. The Version class supports PEP 440 style ordering, which aligns with the conventions used by modern Python packages.

from packaging.version import Version

version1 = Version("2.3.1")
version2 = Version("10.1.2")

if version1 < version2:
    print("Version 1 (2.3.1) is older than Version 2 (10.1.2).")

This approach provides a reliable and consistent method for comparing version strings within Python packages.

Legacy Comparisons

While packaging.version is recommended, an outdated method exists in the form of distutils.version. However, this method is undocumented and complies with the now-superseded PEP 386, making it incompatible with current Python versioning practices.

from distutils.version import LooseVersion, StrictVersion

version1 = LooseVersion("2.3.1")
version2 = LooseVersion("10.1.2")

if version1 < version2:
    print("Version 1 (2.3.1) is older than Version 2 (10.1.2).")

It's important to note that LooseVersion treats PEP 440 versions as "not strict" and does not adhere to the same version comparison logic as Version. Additionally, StrictVersion considers PEP 440 versions invalid and will raise an error when used with such versions.

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