Source code for abydos.distance._hassanat

# Copyright 2019-2020 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
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#
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"""abydos.distance._hassanat.

Hassanat distance
"""

from ._token_distance import _TokenDistance

__all__ = ['Hassanat']


[docs]class Hassanat(_TokenDistance): r"""Hassanat distance. For two multisets X and Y drawn from an alphabet S, Hassanat distance :cite:`Hassanat:2014` is .. math:: dist_{Hassanat}(X, Y) = \sum_{i \in S} D(X_i, Y_i) where .. math:: D(X_i, Y_i) = \left\{\begin{array}{ll} 1-\frac{1+min(X_i, Y_i)}{1+max(X_i, Y_i)}&, min(X_i, Y_i) \geq 0 \\ \\ 1-\frac{1+min(X_i, Y_i)+|min(X_i, Y_i)|} {1+max(X_i, Y_i)+|min(X_i, Y_i)|}&, min(X_i, Y_i) < 0 \end{array}\right. .. versionadded:: 0.4.0 """ def __init__(self, tokenizer=None, **kwargs): """Initialize Hassanat instance. Parameters ---------- tokenizer : _Tokenizer A tokenizer instance from the :py:mod:`abydos.tokenizer` package **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. .. versionadded:: 0.4.0 """ super(Hassanat, self).__init__(tokenizer=tokenizer, **kwargs)
[docs] def dist_abs(self, src, tar): """Return the Hassanat 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 Hassanat distance Examples -------- >>> cmp = Hassanat() >>> cmp.dist_abs('cat', 'hat') 2.0 >>> cmp.dist_abs('Niall', 'Neil') 3.5 >>> cmp.dist_abs('aluminum', 'Catalan') 7.166666666666667 >>> cmp.dist_abs('ATCG', 'TAGC') 5.0 .. versionadded:: 0.4.0 """ self._tokenize(src, tar) distance = 0.0 for tok in self._total().keys(): x = self._src_tokens[tok] y = self._tar_tokens[tok] min_val = min(x, y) if min_val >= 0: distance += 1 - (1 + min_val) / (1 + max(x, y)) else: distance += 1 - 1 / (1 + max(x, y) - min_val) return distance
[docs] def dist(self, src, tar): """Return the normalized Hassanat 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 Normalized Hassanat distance Examples -------- >>> cmp = Hassanat() >>> cmp.dist('cat', 'hat') 0.3333333333333333 >>> cmp.dist('Niall', 'Neil') 0.3888888888888889 >>> cmp.dist('aluminum', 'Catalan') 0.4777777777777778 >>> cmp.dist('ATCG', 'TAGC') 0.5 .. versionadded:: 0.4.0 """ if src == tar: return 0.0 return self.dist_abs(src, tar) / len(self._total().keys())
if __name__ == '__main__': import doctest doctest.testmod()