This is a Python 3 implementation of the Unicode Collation Algorithm (UCA). It passes 100% of the UCA conformances tests for Unicode 6.3.0 with a variable-weighting setting of Non-ignorable.

In short, sorting non-English strings properly.

The core of the algorithm involves multi-level comparison. For example, café comes before caff because at the primary level, the accent is ignored and the first word is treated as if it were cafe. The secondary level (which considers accents) only applies then to words that are equivalent at the primary level.

The Unicode Collation Algorithm and pyuca also support contraction and expansion. Contraction is where multiple letters are treated as a single unit. In Spanish, ch is treated as a letter coming between c and d so that, for example, words beginning ch should sort after all other words beginnings with c. Expansion is where a single letter is treated as though it were multiple letters. In German, ä is sorted as if it were ae, i.e. after ad but before af.

Here is how to use the pyuca module.

pip install pyuca

Usage example:

from pyuca import Collator
c = Collator()

sorted_words = sorted(words, key=c.sort_key)

Collator can also take an optional filename for specifying a custom collation element table.

Python code is made available under an MIT license (see LICENSE). allkeys.txt is made available under the similar license defined in LICENSE-allkeys.