# Copyright 2018-2020 by Christopher C. Little.
# This file is part of Abydos.
#
# Abydos is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Abydos is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Abydos. If not, see <http://www.gnu.org/licenses/>.
"""abydos.distance._yule_q_ii.
Yule's Q dissimilarity
"""
from ._token_distance import _TokenDistance
__all__ = ['YuleQII']
[docs]class YuleQII(_TokenDistance):
r"""Yule's Q dissimilarity.
For two sets X and Y and a population N, Yule's Q dissimilarity
:cite:`Yule:1968` is
.. math::
dist_{Yule_QII}(X, Y) =
\frac{2 \cdot |X \setminus Y| \cdot |Y \setminus X|}
{|X \cap Y| \cdot |(N \setminus X) \setminus Y| +
|X \setminus Y| \cdot |Y \setminus X|}
In :ref:`2x2 confusion table terms <confusion_table>`, where a+b+c+d=n,
this is
.. math::
dist_{Yule_QII} =
\frac{2bc}{ad+bc}
.. versionadded:: 0.4.0
"""
def __init__(
self,
alphabet=None,
tokenizer=None,
intersection_type='crisp',
**kwargs
):
"""Initialize YuleQII instance.
Parameters
----------
alphabet : Counter, collection, int, or None
This represents the alphabet of possible tokens.
See :ref:`alphabet <alphabet>` description in
:py:class:`_TokenDistance` for details.
tokenizer : _Tokenizer
A tokenizer instance from the :py:mod:`abydos.tokenizer` package
intersection_type : str
Specifies the intersection type, and set type as a result:
See :ref:`intersection_type <intersection_type>` description in
:py:class:`_TokenDistance` for details.
**kwargs
Arbitrary keyword arguments
Other Parameters
----------------
qval : int
The length of each q-gram. Using this parameter and tokenizer=None
will cause the instance to use the QGram tokenizer with this
q value.
metric : _Distance
A string distance measure class for use in the ``soft`` and
``fuzzy`` variants.
threshold : float
A threshold value, similarities above which are counted as
members of the intersection for the ``fuzzy`` variant.
.. versionadded:: 0.4.0
"""
super(YuleQII, self).__init__(
alphabet=alphabet,
tokenizer=tokenizer,
intersection_type=intersection_type,
**kwargs
)
[docs] def dist_abs(self, src, tar):
"""Return Yule's Q dissimilarity of two strings.
Parameters
----------
src : str
Source string (or QGrams/Counter objects) for comparison
tar : str
Target string (or QGrams/Counter objects) for comparison
Returns
-------
float
Yule's Q II distance
Examples
--------
>>> cmp = YuleQII()
>>> cmp.dist_abs('cat', 'hat')
0.005128205128205128
>>> cmp.dist_abs('Niall', 'Neil')
0.015364916773367477
>>> cmp.dist_abs('aluminum', 'Catalan')
0.13575757575757577
>>> cmp.dist_abs('ATCG', 'TAGC')
2.0
.. versionadded:: 0.4.0
"""
self._tokenize(src, tar)
a = self._intersection_card()
b = self._src_only_card()
c = self._tar_only_card()
d = self._total_complement_card()
if not b or not c:
return 0.0
return (2 * b * c) / (a * d + b * c)
[docs] def dist(self, src, tar):
"""Return normalized Yule's Q dissimilarity of two strings.
Parameters
----------
src : str
Source string (or QGrams/Counter objects) for comparison
tar : str
Target string (or QGrams/Counter objects) for comparison
Returns
-------
float
Normalized Yule's Q II distance
Examples
--------
>>> cmp = YuleQII()
>>> cmp.dist('cat', 'hat')
0.002564102564102564
>>> cmp.dist('Niall', 'Neil')
0.0076824583866837385
>>> cmp.dist('aluminum', 'Catalan')
0.06787878787878789
>>> cmp.dist('ATCG', 'TAGC')
1.0
.. versionadded:: 0.4.0
"""
return self.dist_abs(src, tar) / 2.0
if __name__ == '__main__':
import doctest
doctest.testmod()