• Cologne-phonetics
  • Introduction
  • Examples
• Installation
• Usage
  • Module contents
    • encode
    • compare
  • Examples
  • Command line interface
• Special characters
  • Word breaks and hyphens
  • Umlaut and special character replacement
• Changelog
  • 1.2.0
  • 1.2.1
  • 1.2.2
  • 1.2.3
  • 1.2.4
  • 1.3.0
  • 1.3.1
  • 2.0.0

Cologne-phonetics is a phonetic algorithm similar to Soundex, wich encodes words into a phonetic code, making it possible to compare how they sound rather than how they're written. It was developed by Hans Postel and contrary to Soundex, it's designed specific for the german language.

It involves three steps:

• Generate a code by representing every letter from left to right with a digit, according to a conversion table
• Remove double digits
• Remove every occurrence of '0', except as a leading digit

The module itself is quite simple and consists only of the encode and compare functions and a simple command line interface.

$ cologne_phonetics.py "peter pédter"
127, 127
$ cologne_phonetics.py "umwelt umhwält"
06352, 06352
$ cologne_phonetics.py "urlaub uhrlaup"
0751, 0751

As you can see, similar sounding names produce the same result, with respect to the correct pronunciation.

$ cologne_phonetics.py "peter peta"
127, 12

This does not give the same result for each word because they may look similar, but (when pronounced correctly) don't really sound alike.

cologne_phonetics runs with Python 3.4+ or PyPy 3.5. It is available on PyPi and can be installed it via pip:

pip install cologne_phonetics

$ cologne_phonetics.py hello
05
$ cologne_phonetics.py hello world
05, 3752

-h, --help

show this help message and exit

-c, --concat

treat words connected by hyphens as seperate words

-v, --verbose

show detailed information

-p, --pretty

format output nicely

Special characters are all characters that are not ascii-characters between A and Z. Most special characters are simply ignored, but even within the set of special characters, there are some that are even more special.

By default, words connected by hyphens, e.g. meier-lüdenscheid are seperated. So meier-lüdenscheid would become '67', '52682'. If you want it to be treated as a single word, you can pass a concat=True to the encode functions.

While at first this doesn't seem to make a difference in the result, other than it being split into a list of strings, in some cases it can make a difference.

>>> cologne_phonetics.encode("weiss-chemie")
>>> [('weiss', '38'), ('chemie', '46')]
>>> cologne_phonetics.encode("weiss-chemie", concat=True)
>>> [('weiss-chemie', '386')]

As you can see, a 4 got lost here. In case you really want to compare the concatenated words you may use this option, but in general there's not much use to it.

Umlaute and some other special characters are converted to their non-special equivalent.

• Removed encode_many()
• encode() now allways returns a list of result tuples
• Added --verbose and --pretty options to CLI
• New function: compare()

• Fixed an error that would lead to case sensitive comparison in compare

• Another error in compare was found (and fixed); Compare didn't actually compare output. It compared input. This was due to bad tests and introduced in 1.2.0, with the change that made encode always return a tuple as a result

• PyPy 3.5 is now officially supported
• A bug was fixed that would lead encode to sometimes an preprocessed rather than the altered string in the result tuple

• Drop support for Python 3.4 and 3.5
• Add tests for Python 3.8 and 3.9
• Remove deprecated Iterable import. See #1

• Add more robust replacement of diacritic using unicodedata (provided by Tobias Bengfort )
• Add type hints
• Fix issue where concat parameter of compare wasn't passed to encode

• Run tests against Python 3.10
• Add missing Readme to pyproject.toml
• Drop Python 3.6 support

• Drop Python 3.7 support
• Test against Python 3.11 and 3.12