========== StringDist

This package provides the stringdist module, which includes functions for calculating raw and normalized versions of the following string distance measurements:

• Levenshtein distance
• Restricted Damerau-Levenshtein distance (a.k.a. optimal string alignment distance)

For optimal performance, the package compiles and uses a C extension module under the hood, but a Python implementation is included as well and will automatically be used if C extensions are not supported by the system (e.g. when the selected interpreter is PyPy).

Installation

To install this package, just use pip::

pip install StringDist

All Python versions >=3.3 should be supported.

Usage

To use the package, simply import the stringdist module and call the desired function, passing in two strings::

import stringdist
stringdist.levenshtein('test', 'testing')

The available functions are as follows:

• levenshtein
• levenshtein_norm
• rdlevenshtein
• rdlevenshtein_norm

Raw distances assume that every allowed operation has a cost of 1. Normalized distances are floats in the range [0.0, 1.0], where 0.0 always corresponds to a raw value of 0 and 1.0 always corresponds to the length of the longer string, i.e. the biggest possible raw value.

Note: The restricted Damerau-Levenshtein distance is not a true distance metric because it does not satisfy the triangle inequality <https://en.wikipedia.org/wiki/Triangle_inequality>_. This makes it a poor choice for applications that involve evaluating the similarity of more than two strings, such as clustering.

Bugs and Requests

Please use GitHub Issues <https://github.com/obulkin/string-dist/issues>_ for bugs and feature requests, checking first to make sure you're not creating a duplicate issue.

Contributing

Pull requests are welcome. Please discuss your plans first by creating a GitHub issue and use good coding style. For Python, this means following the rules laid out in PEP 8 and other relevant PEPs. If in doubt, use a linter like Pylint <https://www.pylint.org>_.

To run unit tests::

git clone https://github.com/obulkin/string-dist.git {directory}
cd {directory}
python setup.py install
python -m unittest -v test_stringdist

You can run tests without installing the package, but this will always cause the Python implementation to be used as the C variant has to be compiled first. By the same token, any changes to the C code will require recompilation before showing up in the tests, which can be handled by running python setup.py install again.

Contributors

• Oleg Bulkin [email protected]