abydos.distance._guth.Guth.sim() - Code Metrics - chrislit/abydos - Measure and Improve Code Quality continuously with Scrutinizer

abydos.distance._guth.Guth.sim() F
last analyzed 2020-12-31 20:10 UTC

↳ Parent: abydos.distance._guth

Complexity

Conditions

Size

Total Lines	100
Code Lines	51

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	50
CRAP Score	33

Importance

Changes

Metric	Value
eloc	51
dl	0
loc	100
ccs	50
cts	50
cp	1
rs	0
c	0
b	0
f	0
cc	33
nop	3
crap	33

How to fix Long Method Complexity

# 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
# 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._guth.

Guth matching algorithm
"""

from typing import Any, List, Optional, Union

from ._distance import _Distance
from ..tokenizer import QGrams, _Tokenizer

__all__ = ['Guth']


class Guth(_Distance):
    r"""Guth matching.

    Guth matching :cite:`Guth:1976` uses a simple positional matching rule list
    to determine whether two names match. Following the original, the
    :meth:`.sim_score` method returns only 1.0 for matching or 0.0 for
    non-matching.

    The :math:`.sim` mathod instead penalizes more distant matches and never
    outrightly declares two names a non-matching unless no matches can be made
    in the two strings.

    Tokens other than single characters can be matched by specifying a
    tokenizer during initialization or setting the qval parameter.

    .. versionadded:: 0.4.1
    """

    def __init__(
        self, tokenizer: Optional[_Tokenizer] = None, **kwargs: Any
    ) -> None:
        """Initialize Guth 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:: 0.4.1

        """
        super(Guth, self).__init__(**kwargs)

        self.params['tokenizer'] = tokenizer
        if 'qval' in self.params:
            self.params['tokenizer'] = QGrams(
                qval=self.params['qval'], start_stop='$#', skip=0, scaler=None
            )

    def _token_at(
        self, name: Union[List[str], str], pos: int
    ) -> Optional[str]:
        """Return the token of name at position pos.

        Parameters
        ----------
        name : str or list
            A string (or list) from which to return a token
        pos : int
            The position of the token to return

        Returns
        -------
        str
            The requested token or None if the position is invalid


        .. versionadded:: 0.4.1

        """
        if pos < 0:
            return None
        if pos >= len(name):
            return None
        return name[pos]

    def sim_score(self, src: str, tar: str) -> float:
        """Return the Guth matching score of two strings.

        Parameters
        ----------
        src : str
            Source string for comparison
        tar : str
            Target string for comparison

        Returns
        -------
        float
            Guth matching score (1.0 if matching, otherwise 0.0)

        Examples
        --------
        >>> cmp = Guth()
        >>> cmp.sim_score('cat', 'hat')
        1.0
        >>> cmp.sim_score('Niall', 'Neil')
        1.0
        >>> cmp.sim_score('aluminum', 'Catalan')
        0.0
        >>> cmp.sim_score('ATCG', 'TAGC')
        1.0


        .. versionadded:: 0.4.1

        """
        if src == tar:
            return 1.0
        if not src or not tar:
            return 0.0

        if self.params['tokenizer']:
            src = self.params['tokenizer'].tokenize(src).get_list()
            tar = self.params['tokenizer'].tokenize(tar).get_list()

        for pos in range(len(src)):
            s = self._token_at(src, pos)
            if s and s in set(tar[max(0, pos - 1) : pos + 3]):
                continue

            t = self._token_at(tar, pos)
            if t and t in set(src[max(0, pos - 1) : pos + 3]):
                continue

            s = self._token_at(src, pos + 1)
            t = self._token_at(tar, pos + 1)
            if s and t and s == t:
                continue

            s = self._token_at(src, pos + 2)
            t = self._token_at(tar, pos + 2)
            if s and t and s == t:
                continue

            break
        else:
            return 1.0
        return 0.0

    def sim(self, src: str, tar: str) -> float:
        """Return the relative Guth similarity of two strings.

        This deviates from the algorithm described in :cite:`Guth:1976` in that
        more distant matches are penalized, so that less similar terms score
        lower that more similar terms.

        If no match is found for a particular token in the source string, this
        does not result in an automatic 0.0 score. Rather, the score is further
        penalized towards 0.0.

        Parameters
        ----------
        src : str
            Source string for comparison
        tar : str
            Target string for comparison

        Returns
        -------
        float
            Relative Guth matching score

        Examples
        --------
        >>> cmp = Guth()
        >>> cmp.sim('cat', 'hat')
        0.8666666666666667
        >>> cmp.sim('Niall', 'Neil')
        0.8800000000000001
        >>> cmp.sim('aluminum', 'Catalan')
        0.4
        >>> cmp.sim('ATCG', 'TAGC')
        0.8


        .. versionadded:: 0.4.1

        """
        if src == tar:
            return 1.0
        if not src or not tar:
            return 0.0

        if self.params['tokenizer']:
            src = self.params['tokenizer'].tokenize(src).get_list()
            tar = self.params['tokenizer'].tokenize(tar).get_list()

        score = 0.0
        for pos in range(len(src)):
            s = self._token_at(src, pos)
            t = self._token_at(tar, pos)
            if s and t and s == t:
                score += 1.0
                continue

            t = self._token_at(tar, pos + 1)
            if s and t and s == t:
                score += 0.8
                continue

            t = self._token_at(tar, pos + 2)
            if s and t and s == t:
                score += 0.6
                continue

            t = self._token_at(tar, pos - 1)
            if s and t and s == t:
                score += 0.8
                continue

            s = self._token_at(src, pos - 1)
            t = self._token_at(tar, pos)
            if s and t and s == t:
                score += 0.8
                continue

            s = self._token_at(src, pos + 1)
            if s and t and s == t:
                score += 0.8
                continue

            s = self._token_at(src, pos + 2)
            if s and t and s == t:
                score += 0.6
                continue

            s = self._token_at(src, pos + 1)
            t = self._token_at(tar, pos + 1)
            if s and t and s == t:
                score += 0.6
                continue

            s = self._token_at(src, pos + 2)
            t = self._token_at(tar, pos + 2)
            if s and t and s == t:
                score += 0.2
                continue

        return score / len(src)


if __name__ == '__main__':
    import doctest

    doctest.testmod()


1		# Copyright 2019-2020 by Christopher C. Little.
2		# This file is part of Abydos.
3		#
4		# Abydos is free software: you can redistribute it and/or modify
5		# it under the terms of the GNU General Public License as published by
6		# the Free Software Foundation, either version 3 of the License, or
7		# (at your option) any later version.
8		#
9		# Abydos is distributed in the hope that it will be useful,
10		# but WITHOUT ANY WARRANTY; without even the implied warranty of
11		# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12		# GNU General Public License for more details.
13		#
14		# You should have received a copy of the GNU General Public License
15		# along with Abydos. If not, see <http://www.gnu.org/licenses/>.
16
17		"""abydos.distance._guth.
18
19	1	Guth matching algorithm
20		"""
21
22		from typing import Any, List, Optional, Union
23
24	1	from ._distance import _Distance
25		from ..tokenizer import QGrams, _Tokenizer
26
27		__all__ = ['Guth']
28
29
30		class Guth(_Distance):
31	1	r"""Guth matching.
32	1
33		Guth matching :cite:`Guth:1976` uses a simple positional matching rule list
34	1	to determine whether two names match. Following the original, the
35		:meth:`.sim_score` method returns only 1.0 for matching or 0.0 for
36		non-matching.
37	1
38		The :math:`.sim` mathod instead penalizes more distant matches and never
39		outrightly declares two names a non-matching unless no matches can be made
40		in the two strings.
41
42		Tokens other than single characters can be matched by specifying a
43		tokenizer during initialization or setting the qval parameter.
44
45		.. versionadded:: 0.4.1
46		"""
47
48		def __init__(
49		self, tokenizer: Optional[_Tokenizer] = None, **kwargs: Any
50		) -> None:
51		"""Initialize Guth instance.
52
53		Parameters
54		----------
55	1	tokenizer : _Tokenizer
56		A tokenizer instance from the :py:mod:`abydos.tokenizer` package
57		**kwargs
58		Arbitrary keyword arguments
59
60		Other Parameters
61		----------------
62		qval : int
63		The length of each q-gram. Using this parameter and tokenizer=None
64		will cause the instance to use the QGram tokenizer with this
65		q value.
66
67
68		.. versionadded:: 0.4.1
69
70		"""
71		super(Guth, self).__init__(**kwargs)
72
73		self.params['tokenizer'] = tokenizer
74		if 'qval' in self.params:
75		self.params['tokenizer'] = QGrams(
76	1	qval=self.params['qval'], start_stop='$#', skip=0, scaler=None
77		)
78	1
79	1	def _token_at(
80	1	self, name: Union[List[str], str], pos: int
81		) -> Optional[str]:
82		"""Return the token of name at position pos.
83
84	1	Parameters
85		----------
86		name : str or list
87		A string (or list) from which to return a token
88		pos : int
89		The position of the token to return
90
91		Returns
92		-------
93		str
94		The requested token or None if the position is invalid
95
96
97		.. versionadded:: 0.4.1
98
99		"""
100		if pos < 0:
101		return None
102		if pos >= len(name):
103	1	return None
104	1	return name[pos]
105	1
106	1	def sim_score(self, src: str, tar: str) -> float:
107	1	"""Return the Guth matching score of two strings.
108
109	1	Parameters
110		----------
111		src : str
112		Source string for comparison
113		tar : str
114		Target string for comparison
115
116		Returns
117		-------
118		float
119		Guth matching score (1.0 if matching, otherwise 0.0)
120
121		Examples
122		--------
123		>>> cmp = Guth()
124		>>> cmp.sim_score('cat', 'hat')
125		1.0
126		>>> cmp.sim_score('Niall', 'Neil')
127		1.0
128		>>> cmp.sim_score('aluminum', 'Catalan')
129		0.0
130		>>> cmp.sim_score('ATCG', 'TAGC')
131		1.0
132
133
134		.. versionadded:: 0.4.1
135
136		"""
137		if src == tar:
138		return 1.0
139		if not src or not tar:
140	1	return 0.0
141	1
142	1	if self.params['tokenizer']:
143	1	src = self.params['tokenizer'].tokenize(src).get_list()
144		tar = self.params['tokenizer'].tokenize(tar).get_list()
145	1
146	1	for pos in range(len(src)):
147	1	s = self._token_at(src, pos)
148		if s and s in set(tar[max(0, pos - 1) : pos + 3]):
149	1	continue
150	1
151	1	t = self._token_at(tar, pos)
152	1	if t and t in set(src[max(0, pos - 1) : pos + 3]):
153	1	continue
154
155	1	s = self._token_at(src, pos + 1)
156	1	t = self._token_at(tar, pos + 1)
157	1	if s and t and s == t:
158	1	continue
159
160	1	s = self._token_at(src, pos + 2)
161	1	t = self._token_at(tar, pos + 2)
162	1	if s and t and s == t:
163	1	continue
164
165	1	break
166	1	else:
167	1	return 1.0
168	1	return 0.0
169
170	1	def sim(self, src: str, tar: str) -> float:
171		"""Return the relative Guth similarity of two strings.
172	1
173	1	This deviates from the algorithm described in :cite:`Guth:1976` in that
174		more distant matches are penalized, so that less similar terms score
175	1	lower that more similar terms.
176
177		If no match is found for a particular token in the source string, this
178		does not result in an automatic 0.0 score. Rather, the score is further
179		penalized towards 0.0.
180
181		Parameters
182		----------
183		src : str
184		Source string for comparison
185		tar : str
186		Target string for comparison
187
188		Returns
189		-------
190		float
191		Relative Guth matching score
192
193		Examples
194		--------
195		>>> cmp = Guth()
196		>>> cmp.sim('cat', 'hat')
197		0.8666666666666667
198		>>> cmp.sim('Niall', 'Neil')
199		0.8800000000000001
200		>>> cmp.sim('aluminum', 'Catalan')
201		0.4
202		>>> cmp.sim('ATCG', 'TAGC')
203		0.8
204
205
206		.. versionadded:: 0.4.1
207
208		"""
209		if src == tar:
210		return 1.0
211		if not src or not tar:
212		return 0.0
213
214	1	if self.params['tokenizer']:
215	1	src = self.params['tokenizer'].tokenize(src).get_list()
216	1	tar = self.params['tokenizer'].tokenize(tar).get_list()
217	1
218		score = 0.0
219	1	for pos in range(len(src)):
220	1	s = self._token_at(src, pos)
221	1	t = self._token_at(tar, pos)
222		if s and t and s == t:
223	1	score += 1.0
224	1	continue
225	1
226	1	t = self._token_at(tar, pos + 1)
227	1	if s and t and s == t:
228	1	score += 0.8
229	1	continue
230
231	1	t = self._token_at(tar, pos + 2)
232	1	if s and t and s == t:
233	1	score += 0.6
234	1	continue
235
236	1	t = self._token_at(tar, pos - 1)
237	1	if s and t and s == t:
238	1	score += 0.8
239	1	continue
240
241	1	s = self._token_at(src, pos - 1)
242	1	t = self._token_at(tar, pos)
243	1	if s and t and s == t:
244	1	score += 0.8
245		continue
246	1
247	1	s = self._token_at(src, pos + 1)
248	1	if s and t and s == t:
249	1	score += 0.8
250	1	continue
251
252	1	s = self._token_at(src, pos + 2)
253	1	if s and t and s == t:
254	1	score += 0.6
255	1	continue
256
257	1	s = self._token_at(src, pos + 1)
258	1	t = self._token_at(tar, pos + 1)
259	1	if s and t and s == t:
260	1	score += 0.6
261		continue
262	1
263	1	s = self._token_at(src, pos + 2)
264	1	t = self._token_at(tar, pos + 2)
265	1	if s and t and s == t:
266	1	score += 0.2
267		continue
268	1
269	1	return score / len(src)
270	1
271	1
272	1	if __name__ == '__main__':
273		import doctest
274	1
275		doctest.testmod()
276

chrislit / abydos

abydos.distance._guth.Guth.sim() F last analyzed 2020-12-31 20:10 UTC

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abydos.distance._guth.Guth.sim() F
last analyzed 2020-12-31 20:10 UTC