Source code for abydos.distance._baulieu_i

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

from ._token_distance import _TokenDistance

__all__ = ['BaulieuI']

[docs]class BaulieuI(_TokenDistance): r"""Baulieu I distance. For two sets X and Y and a population N, Baulieu I distance :cite:`Baulieu:1989` is .. math:: sim_{BaulieuI}(X, Y) = \frac{|X| \cdot |Y| - |X \cap Y|^2}{|X| \cdot |Y|} This is Baulieu's 12th dissimilarity coefficient. In :ref:`2x2 confusion table terms <confusion_table>`, where a+b+c+d=n, this is .. math:: sim_{BaulieuI} = \frac{(a+b)(a+c)-a^2}{(a+b)(a+c)} .. versionadded:: 0.4.0 """ def __init__( self, alphabet=None, tokenizer=None, intersection_type='crisp', **kwargs ): """Initialize BaulieuI 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(BaulieuI, self).__init__( alphabet=alphabet, tokenizer=tokenizer, intersection_type=intersection_type, **kwargs )
[docs] def dist(self, src, tar): """Return the Baulieu I 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 I distance Examples -------- >>> cmp = BaulieuI() >>> cmp.dist('cat', 'hat') 0.75 >>> cmp.dist('Niall', 'Neil') 0.8666666666666667 >>> cmp.dist('aluminum', 'Catalan') 0.9861111111111112 >>> cmp.dist('ATCG', 'TAGC') 1.0 .. versionadded:: 0.4.0 """ self._tokenize(src, tar) a = self._intersection_card() ab = self._src_card() ac = self._tar_card() num = ab * ac - a * a if num == 0: return 0.0 return num / (ab * ac)
if __name__ == '__main__': import doctest doctest.testmod()