Source code for abydos.distance._baulieu_viii

# Copyright 2019-2020 by Christopher C. Little.
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Baulieu VIII distance

from ._token_distance import _TokenDistance

__all__ = ['BaulieuVIII']

[docs]class BaulieuVIII(_TokenDistance): r"""Baulieu VIII distance. For two sets X and Y and a population N, Baulieu VIII distance :cite:`Baulieu:1997` is .. math:: dist_{BaulieuVIII}(X, Y) = \frac{(|X \setminus Y| - |Y \setminus X|)^2}{|N|^2} This is Baulieu's 26th dissimilarity coefficient. This coefficient fails Baulieu's (P5) property, that :math:`D(a,b+1,c,d) \geq D(a,b,c,d)`, with equality holding if :math:`D(a,b,c,d) = 1`. In :ref:`2x2 confusion table terms <confusion_table>`, where a+b+c+d=n, this is .. math:: dist_{BaulieuVIII} = \frac{(b-c)^2}{n^2} .. versionadded:: 0.4.0 """ def __init__( self, alphabet=None, tokenizer=None, intersection_type='crisp', **kwargs ): """Initialize BaulieuVIII 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(BaulieuVIII, self).__init__( alphabet=alphabet, tokenizer=tokenizer, intersection_type=intersection_type, **kwargs )
[docs] def dist(self, src, tar): """Return the Baulieu VIII distance 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 Baulieu VIII distance Examples -------- >>> cmp = BaulieuVIII() >>> cmp.dist('cat', 'hat') 0.0 >>> cmp.dist('Niall', 'Neil') 1.6269262807163682e-06 >>> cmp.dist('aluminum', 'Catalan') 1.6227838857560144e-06 >>> cmp.dist('ATCG', 'TAGC') 0.0 .. versionadded:: 0.4.0 """ self._tokenize(src, tar) bmc = self._src_only_card() - self._tar_only_card() n = self._population_unique_card() if bmc == 0.0: return 0.0 return bmc ** 2 / n ** 2
if __name__ == '__main__': import doctest doctest.testmod()