restructure documentation

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# Contributor Covenant Code of Conduct
## Our Pledge
We as members, contributors, and leaders pledge to make participation in our
community a harassment-free experience for everyone, regardless of age, body
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identity and orientation.
We pledge to act and interact in ways that contribute to an open, welcoming,
diverse, inclusive, and healthy community.
## Our Standards
Examples of behavior that contributes to a positive environment for our
community include:
* Demonstrating empathy and kindness toward other people
* Being respectful of differing opinions, viewpoints, and experiences
* Giving and gracefully accepting constructive feedback
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and learning from the experience
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community
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any kind
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without their explicit permission
* Other conduct which could reasonably be considered inappropriate in a
professional setting
## Enforcement Responsibilities
Community leaders are responsible for clarifying and enforcing our standards of
acceptable behavior and will take appropriate and fair corrective action in
response to any behavior that they deem inappropriate, threatening, offensive,
or harmful.
Community leaders have the right and responsibility to remove, edit, or reject
comments, commits, code, wiki edits, issues, and other contributions that are
not aligned to this Code of Conduct, and will communicate reasons for moderation
decisions when appropriate.
## Scope
This Code of Conduct applies within all community spaces, and also applies when
an individual is officially representing the community in public spaces.
Examples of representing our community include using an official e-mail address,
posting via an official social media account, or acting as an appointed
representative at an online or offline event.
## Enforcement
Instances of abusive, harassing, or otherwise unacceptable behavior may be
reported to the community leaders responsible for enforcement at conduct@maxbachmann.de.
All complaints will be reviewed and investigated promptly and fairly.
All community leaders are obligated to respect the privacy and security of the
reporter of any incident.
## Enforcement Guidelines
Community leaders will follow these Community Impact Guidelines in determining
the consequences for any action they deem in violation of this Code of Conduct:
### 1. Correction
**Community Impact**: Use of inappropriate language or other behavior deemed
unprofessional or unwelcome in the community.
**Consequence**: A private, written warning from community leaders, providing
clarity around the nature of the violation and an explanation of why the
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### 2. Warning
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actions.
**Consequence**: A warning with consequences for continued behavior. No
interaction with the people involved, including unsolicited interaction with
those enforcing the Code of Conduct, for a specified period of time. This
includes avoiding interactions in community spaces as well as external channels
like social media. Violating these terms may lead to a temporary or permanent
ban.
### 3. Temporary Ban
**Community Impact**: A serious violation of community standards, including
sustained inappropriate behavior.
**Consequence**: A temporary ban from any sort of interaction or public
communication with the community for a specified period of time. No public or
private interaction with the people involved, including unsolicited interaction
with those enforcing the Code of Conduct, is allowed during this period.
Violating these terms may lead to a permanent ban.
### 4. Permanent Ban
**Community Impact**: Demonstrating a pattern of violation of community
standards, including sustained inappropriate behavior, harassment of an
individual, or aggression toward or disparagement of classes of individuals.
**Consequence**: A permanent ban from any sort of public interaction within the
community.
## Attribution
This Code of Conduct is adapted from the [Contributor Covenant][homepage],
version 2.1, available at
[https://www.contributor-covenant.org/version/2/1/code_of_conduct.html][v2.1].
Community Impact Guidelines were inspired by
[Mozilla's code of conduct enforcement ladder][Mozilla CoC].
For answers to common questions about this code of conduct, see the FAQ at
[https://www.contributor-covenant.org/faq][FAQ]. Translations are available at
[https://www.contributor-covenant.org/translations][translations].
[homepage]: https://www.contributor-covenant.org
[v2.1]: https://www.contributor-covenant.org/version/2/1/code_of_conduct.html
[Mozilla CoC]: https://github.com/mozilla/diversity
[FAQ]: https://www.contributor-covenant.org/faq
[translations]: https://www.contributor-covenant.org/translations

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License
=======
RapidFuzz is licensed under the MIT license since I believe that everyone should be able to use it without being forced to adopt the GPL license. Thats why the library is based on an older version of fuzzywuzzy that was MIT licensed as well.
This old version of fuzzywuzzy can be found `here <https://github.com/seatgeek/fuzzywuzzy/tree/4bf28161f7005f3aa9d4d931455ac55126918df7>`__.
RapidFuzz is free and open-source software licensed under the MIT license.
MIT License
-----------
.. code-block:: text
Copyright © 2021 Max Bachmann
Copyright © 2011 Adam Cohen
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to
deal in the Software without restriction, including without limitation the
rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
IN THE SOFTWARE.
.. literalinclude:: ../LICENSE

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References
==========
.. bibliography::

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Levenshtein
-----------
.. automodule:: rapidfuzz.distance.Levenshtein
This implementation supports the usage of different weights for
Insertion/Deletion/Substitution. The uniform Levenshtein distance refers to ``weights=(1,1,1)``
and the Indel distance refers to ``weights=(1,1,2)``. All other weights are refered to
as generic Levenshtein distance.
Functions
^^^^^^^^^
distance
~~~~~~~~
.. autofunction:: rapidfuzz.distance.Levenshtein.distance
@ -24,3 +34,82 @@ editops
opcodes
~~~~~~~
.. autofunction:: rapidfuzz.distance.Levenshtein.opcodes
Performance
^^^^^^^^^^^
Since the Levenshtein module uses different implementations based on the weights
used, this leads to different performance characteristics. The following sections
show the performance for the different possible weights.
Uniform
~~~~~~~
The following image shows a benchmark of the uniform Levenshtein distance in
multiple Python libraries. All of them are implemented either in C/C++ or Cython.
The graph shows, that python-Levenshtein is the only library with a time
complexity of ``O(NM)``, while all other libraries have a time complexity of
``O([N/64]M)``. Especially for long strings RapidFuzz is a lot faster than
all the other tested libraries.
.. image:: img/uniform_levenshtein.svg
:align: center
Indel
~~~~~
The following image shows a benchmark of the Indel distance in RapidFuzz
and python-Levenshtein. Similar to the normal Levenshtein distance
python-Levenshtein uses an implementation with a time complexity of ``O(NM)``,
while RapidFuzz has a time complexity of ``O([N/64]M)``.
.. image:: img/indel_levenshtein.svg
:align: center
Implementation Notes
^^^^^^^^^^^^^^^^^^^^
Depending on the used input parameters, different optimized implementation are used
to improve the performance. These implementations are described in the following
sections.
Uniform
~~~~~~~
The implementation for the uniform Levenshtein distance has a worst-case
performance of ``O([N/64]M)``. It uses the following optimized implementations:
- if score_cutoff is 0 the similarity can be calculated using a direct comparision,
since no difference between the strings is allowed. The time complexity of
this algorithm is ``O(N)``.
- A common prefix/suffix of the two compared strings does not affect
the Levenshtein distance, so the affix is removed before calculating the
similarity.
- If score_cutoff is ≤ 3 the mbleven algorithm is used. This algorithm
checks all possible edit operations that are possible under
the threshold `score_cutoff`. The time complexity of this algorithm is ``O(N)``.
- If the length of the shorter string is ≤ 64 after removing the common affix
Hyyrös' algorithm is used, which calculates the Levenshtein distance in
parallel. The algorithm is described by :cite:t:`2003:hyrroe`. The time complexity of this
algorithm is ``O(N)``.
- If the length of the shorter string is ≥ 64 after removing the common affix
a blockwise implementation of Hyyrös' algorithm is used, which calculates
the Levenshtein distance in parallel (64 characters at a time).
The algorithm is described by :cite:t:`2003:hyrroe`. The time complexity of this
algorithm is ``O([N/64]M)``.
Indel
~~~~~
The Indel distance is available as a stand alone implementation. Further details
can be found in `here <Indel.html>`__.
Generic
~~~~~~~
The implementation for other weights is based on Wagner-Fischer.
It has a performance of ``O(N * M)`` and has a memory usage of ``O(N)``.
Further details can be found in :cite:t:`1974:WagFisch`.

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========
Editops
--------------------------
-------
.. autoclass:: rapidfuzz.distance.Editops
:members:
Opcodes
--------------------------
-------
.. autoclass:: rapidfuzz.distance.Opcodes
:members:

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.. mdinclude:: ../CHANGELOG.md

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# extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
# ones.
extensions = [
'sphinx.ext.autodoc', 'sphinx.ext.napoleon'
'sphinx.ext.autodoc', 'sphinx.ext.napoleon', 'sphinxcontrib.bibtex', 'm2r2'
]
bibtex_bibfiles = ['refs.bib']
# Add any paths that contain templates here, relative to this directory.
templates_path = ['_templates']

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Welcome to RapidFuzz's documentation!
=====================================
RapidFuzz
=========
.. toctree::
:maxdepth: 2
:hidden:
Installation
.. toctree::
:maxdepth: 3
Usage/index
.. toctree::
:maxdepth: 1
Contributing
.. toctree::
:maxdepth: 2
:caption: Development
:hidden:
Contributing/index
changelog_link
License
Indices and tables
==================
* :ref:`genindex`
* :ref:`modindex`
* :ref:`search`
References
GitHub Repository <https://github.com/maxbachmann/RapidFuzz>

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@article{2003:hyrroe,
author = {Hyyr\"{o}, Heikki},
title = {A Bit-Vector Algorithm for Computing Levenshtein and Damerau Edit Distances},
year = {2003},
issue_date = {Spring 2003},
publisher = {Publishing Association Nordic Journal of Computing},
address = {FIN},
volume = {10},
number = {1},
issn = {1236-6064},
abstract = {The edit distance between strings A and B is defined as the minimum number of edit operations needed in converting A into B or vice versa. The Levenshtein edit distance allows three types of operations: an insertion, a deletion or a substitution of a character. The Damerau edit distance allows the previous three plus in addition a transposition between two adjacent characters. To our best knowledge the best current practical algorithms for computing these edit distances run in time O(dm) and O(⌈m/w⌉(n + σ)), where d is the edit distance between the two strings, m and n are their lengths (m ≤ n), w is the computer word size and σ is the size of the alphabet. In this paper we present an algorithm that runs in time O(⌈d/w⌉m + ⌈n/w⌉σ) or O(⌈d/w⌉n + ⌈m/w⌉σ). The structure of the algorithm is such, that in practice it is mostly suitable for testing whether the edit distance between two strings is within some pre-determined error threshold. We also present some initial test results with thresholded edit distance computation. In them our algorithm works faster than the original algorithm of Myers.},
journal = {Nordic J. of Computing},
month = {mar},
pages = {2939},
numpages = {11},
keywords = {bit-parallelism, approximate string matching, Levenshtein edit distance, Damerau edit distance}
}
@article{1974:WagFisch,
author = {Wagner, Robert A. and Fischer, Michael J.},
title = {The String-to-String Correction Problem},
year = {1974},
issue_date = {Jan. 1974},
publisher = {Association for Computing Machinery},
address = {New York, NY, USA},
volume = {21},
number = {1},
issn = {0004-5411},
url = {https://doi.org/10.1145/321796.321811},
doi = {10.1145/321796.321811},
abstract = {The string-to-string correction problem is to determine the distance between two strings as measured by the minimum cost sequence of “edit operations” needed to change the one string into the other. The edit operations investigated allow changing one symbol of a string into another single symbol, deleting one symbol from a string, or inserting a single symbol into a string. An algorithm is presented which solves this problem in time proportional to the product of the lengths of the two strings. Possible applications are to the problems of automatic spelling correction and determining the longest subsequence of characters common to two strings.},
journal = {J. ACM},
month = {jan},
pages = {168173},
numpages = {6}
}

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Sphinx
furo
numpy
sphinxcontrib-bibtex
m2r2

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@ -81,11 +81,6 @@ def distance(s1, s2, *, processor=None, score_cutoff=None):
distance : int
distance between s1 and s2
Raises
------
ValueError
If unsupported weights are provided a ValueError is thrown
Notes
-----
The following implementation is used with a worst-case performance of ``O([N/64]M)``.
@ -186,11 +181,6 @@ def similarity(s1, s2, *, processor=None, score_cutoff=None):
similarity : int
similarity between s1 and s2
Raises
------
ValueError
If unsupported weights are provided a ValueError is thrown
See Also
--------
Indel.distance : Indel distance

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# distutils: language=c++
# cython: language_level=3, binding=True, linetrace=True
"""
The Levenshtein (edit) distance is a string metric to measure the
difference between two strings/sequences s1 and s2.
It's defined as the minimum number of insertions, deletions or
substitutions required to transform s1 into s2.
"""
from _initialize import Editops
from _initialize cimport Editops, RfEditops
from array import array
@ -95,114 +102,6 @@ def distance(s1, s2, *, weights=(1,1,1), processor=None, score_cutoff=None):
ValueError
If unsupported weights are provided a ValueError is thrown
Notes
-----
Depending on the input parameters different optimized implementation are used
to improve the performance.
Insertion = Deletion = Substitution:
This is known as uniform Levenshtein distance and is the distance most commonly
referred to as Levenshtein distance. The following implementation is used
with a worst-case performance of ``O([N/64]M)``.
- if max is 0 the similarity can be calculated using a direct comparision,
since no difference between the strings is allowed. The time complexity of
this algorithm is ``O(N)``.
- A common prefix/suffix of the two compared strings does not affect
the Levenshtein distance, so the affix is removed before calculating the
similarity.
- If max is 3 the mbleven algorithm is used. This algorithm
checks all possible edit operations that are possible under
the threshold `max`. The time complexity of this algorithm is ``O(N)``.
- If the length of the shorter string is 64 after removing the common affix
Hyyrös' algorithm is used, which calculates the Levenshtein distance in
parallel. The algorithm is described by [1]_. The time complexity of this
algorithm is ``O(N)``.
- If the length of the shorter string is 64 after removing the common affix
a blockwise implementation of Myers' algorithm is used, which calculates
the Levenshtein distance in parallel (64 characters at a time).
The algorithm is described by [3]_. The time complexity of this
algorithm is ``O([N/64]M)``.
The following image shows a benchmark of the Levenshtein distance in multiple
Python libraries. All of them are implemented either in C/C++ or Cython.
The graph shows, that python-Levenshtein is the only library with a time
complexity of ``O(NM)``, while all other libraries have a time complexity of
``O([N/64]M)``. Especially for long strings RapidFuzz is a lot faster than
all the other tested libraries.
.. image:: img/uniform_levenshtein.svg
Insertion = Deletion, Substitution >= Insertion + Deletion:
Since every Substitution can be performed as Insertion + Deletion, this variant
of the Levenshtein distance only uses Insertions and Deletions. Therefore this
variant is often referred to as InDel-Distance. The following implementation
is used with a worst-case performance of ``O([N/64]M)``.
- if max is 0 the similarity can be calculated using a direct comparision,
since no difference between the strings is allowed. The time complexity of
this algorithm is ``O(N)``.
- if max is 1 and the two strings have a similar length, the similarity can be
calculated using a direct comparision aswell, since a substitution would cause
a edit distance higher than max. The time complexity of this algorithm
is ``O(N)``.
- A common prefix/suffix of the two compared strings does not affect
the Levenshtein distance, so the affix is removed before calculating the
similarity.
- If max is 4 the mbleven algorithm is used. This algorithm
checks all possible edit operations that are possible under
the threshold `max`. As a difference to the normal Levenshtein distance this
algorithm can even be used up to a threshold of 4 here, since the higher weight
of substitutions decreases the amount of possible edit operations.
The time complexity of this algorithm is ``O(N)``.
- If the length of the shorter string is 64 after removing the common affix
Hyyrös' lcs algorithm is used, which calculates the Indel distance in
parallel. The algorithm is described by [4]_ and is extended with support
for UTF32 in this implementation. The time complexity of this
algorithm is ``O(N)``.
- If the length of the shorter string is 64 after removing the common affix
a blockwise implementation of the Hyyrös' lcs algorithm is used, which calculates
the Levenshtein distance in parallel (64 characters at a time).
The algorithm is described by [4]_. The time complexity of this
algorithm is ``O([N/64]M)``.
The following image shows a benchmark of the Indel distance in RapidFuzz
and python-Levenshtein. Similar to the normal Levenshtein distance
python-Levenshtein uses a implementation with a time complexity of ``O(NM)``,
while RapidFuzz has a time complexity of ``O([N/64]M)``.
.. image:: img/indel_levenshtein.svg
Other weights:
The implementation for other weights is based on Wagner-Fischer.
It has a performance of ``O(N * M)`` and has a memory usage of ``O(N)``.
Further details can be found in [2]_.
References
----------
.. [1] Hyyrö, Heikki. "A Bit-Vector Algorithm for Computing
Levenshtein and Damerau Edit Distances."
Nordic Journal of Computing, Volume 10 (2003): 29-39.
.. [2] Wagner, Robert & Fischer, Michael
"The String-to-String Correction Problem."
J. ACM. 21. (1974): 168-173
.. [3] Myers, Gene. "A fast bit-vector algorithm for approximate
string matching based on dynamic programming."
Journal of the ACM (JACM) 46.3 (1999): 395-415.
.. [4] Hyyrö, Heikki. "Bit-Parallel LCS-length Computation Revisited"
Proc. 15th Australasian Workshop on Combinatorial Algorithms (AWOCA 2004).
Examples
--------
Find the Levenshtein distance between two strings: