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Text sorting function for the Czech language

Project description

Czech Sort

This is a pure-Python library for Czech-language alphabetical sorting.

Quick Use

From Python:

>>> import czech_sort

>>> czech_sort.sorted(['sídliště', 'shoda', 'schody'])
['shoda', 'schody', 'sídliště']

>>> sorted(['sídliště', 'shoda', 'schody'], key=czech_sort.key)
['shoda', 'schody', 'sídliště']

On the command line::

$ python -m czech_sort < file.txt

Why another sorting library?

To sort Python strings in the Czech language, there are three other options:

  • Use PyICU. This can sort really well, and do all kinds of wonderful, standards-compliant Unicode things. Perfect for publication-quality results. Unfortunately, ICU can be a major pain to install, making it overkill if you just want to sort a list of strings.
  • Set the locale, then use locale.strxfrm. (Yes, strxfrm! Try saying that ten times fast!) This depends on the Czech POSIX locale being available, so it's hardly portable.
  • Just use Python's built-in string sort. This sorts lexicographically by Unicode codepoints. It might be good enough for you? Maybe?


The czech-sort library is a compromise. It should give you good results in the 99% case.

Do not use this if you need proper sorting of symbols, non-Latin scripts, or diacritics other than Czech/Slovak.

Any other deviation from the relevant standard, ČSN 97 6030, should be considered a bug. However, neither the author nor the community at large have access to the standard, which makes finding such bugs somewhat difficult.

Full API


Takes an iterable of strings, and returns a list of them, sorted.


Returns a sort key object for a given string.

This function is suitable as the key for functions like the built-in sorted or list.sort.


Returns a sort key for a given string, as bytes.

This is suitable as a DB-API custom function like the built-in sqlite3 connection's create_function.

WARNING: Do not store the results of this function. The format can change in future versions of czech_sort.


The czech-sort library can be used with Python 2.6+ and 3.5+.

Under Python 2, it only accepts unicode strings.


Install this into your virtualenv by running:

$ pip install czech-sort


Bug reports and comments are welcome at Github.

Patches are also welcome! Source code is hosted at Github:

$ git clone

To run the included tests:

$ python -m pip install -e.[test]
$ python -m pytest

If you would like to contribute, but are confused by the above, then please e-mail encukou at gmail dot com.


The project is licensed under the MIT license. May it serve you well.


1.1.0 (2023-07-11)

  • Add bytes_key (Thanks to @honzajavorek!)
  • Drop support for Python 2

1.0.1 (2021-08-30)

  • Fix bug that prevented sorting strings that contain 'Ł' and/or 'Ø'. (Thanks to @dark-light-cz for reporting and @jiri-one for the PR!)

1.0.0 (2020-09-14)

No code changes. Since this has been stable for five years I decided to call it 1.0.

  • Packaging improvements
  • Tested with Python 2.7 and 3.5-3.9

0.4 (2015-09-05)

  • First general release

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