abydos/distance/_typo.py
# 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._typo.
Typo edit distance functions.
"""
from itertools import chain
from math import log
from typing import Any, Dict, Tuple, cast
from numpy import float_ as np_float
from numpy import zeros as np_zeros
from ._distance import _Distance
__all__ = ['Typo']
class Typo(_Distance):
"""Typo distance.
This is inspired by Typo-Distance :cite:`Song:2011`, and a fair bit of
this was copied from that module. Compared to the original, this supports
different metrics for substitution.
.. versionadded:: 0.3.6
"""
# fmt: off
_keyboard = {'QWERTY': (
(('`', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '-', '='),
('', 'q', 'w', 'e', 'r', 't', 'y', 'u', 'i', 'o', 'p', '[', ']',
'\\'),
('', 'a', 's', 'd', 'f', 'g', 'h', 'j', 'k', 'l', ';', "'"),
('', 'z', 'x', 'c', 'v', 'b', 'n', 'm', ',', '.', '/'),
('', '', '', ' ')),
(('~', '!', '@', '#', '$', '%', '^', '&', '*', '(', ')', '_', '+'),
('', 'Q', 'W', 'E', 'R', 'T', 'Y', 'U', 'I', 'O', 'P', '{', '}', '|'),
('', 'A', 'S', 'D', 'F', 'G', 'H', 'J', 'K', 'L', ':', '"'),
('', 'Z', 'X', 'C', 'V', 'B', 'N', 'M', '<', '>', '?'),
('', '', '', ' '))
), 'Dvorak': (
(('`', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '[', ']'),
('', "'", ',', '.', 'p', 'y', 'f', 'g', 'c', 'r', 'l', '/', '=',
'\\'),
('', 'a', 'o', 'e', 'u', 'i', 'd', 'h', 't', 'n', 's', '-'),
('', ';', 'q', 'j', 'k', 'x', 'b', 'm', 'w', 'v', 'z'),
('', '', '', ' ')),
(('~', '!', '@', '#', '$', '%', '^', '&', '*', '(', ')', '{', '}'),
('', '"', '<', '>', 'P', 'Y', 'F', 'G', 'C', 'R', 'L', '?', '+', '|'),
('', 'A', 'O', 'E', 'U', 'I', 'D', 'H', 'T', 'N', 'S', '_'),
('', ':', 'Q', 'J', 'K', 'X', 'B', 'M', 'W', 'V', 'Z'),
('', '', '', ' '))
), 'AZERTY': (
(('²', '&', 'é', '"', "'", '(', '-', 'è', '_', 'ç', 'à', ')', '='),
('', 'a', 'z', 'e', 'r', 't', 'y', 'u', 'i', 'o', 'p', '', '$'),
('', 'q', 's', 'd', 'f', 'g', 'h', 'j', 'k', 'l', 'm', 'ù', '*'),
('<', 'w', 'x', 'c', 'v', 'b', 'n', ',', ';', ':', '!'),
('', '', '', ' ')),
(('~', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '°', '+'),
('', 'A', 'W', 'E', 'R', 'T', 'Y', 'U', 'I', 'O', 'P', '', '£'),
('', 'Q', 'S', 'D', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'Ù', 'μ'),
('>', 'W', 'X', 'C', 'V', 'B', 'N', '?', '.', '/', '§'),
('', '', '', ' '))
), 'QWERTZ': (
(('', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', 'ß', ''),
('', 'q', 'w', 'e', 'r', 't', 'z', 'u', 'i', 'o', 'p', ' ü', '+',
'\\'),
('', 'a', 's', 'd', 'f', 'g', 'h', 'j', 'k', 'l', 'ö', 'ä', '#'),
('<', 'y', 'x', 'c', 'v', 'b', 'n', 'm', ',', '.', '-'),
('', '', '', ' ')),
(('°', '!', '"', '§', '$', '%', '&', '/', '(', ')', '=', '?', ''),
('', 'Q', 'W', 'E', 'R', 'T', 'Z', 'U', 'I', 'O', 'P', 'Ü', '*', ''),
('', 'A', 'S', 'D', 'F', 'G', 'H', 'J', 'K', 'L', 'Ö', 'Ä', "'"),
('>', 'Y', 'X', 'C', 'V', 'B', 'N', 'M', ';', ':', '_'),
('', '', '', ' '))
), 'QWERTZ_HUN': (
(('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'ö', 'ü', 'ó'),
('', 'q', 'w', 'e', 'r', 't', 'z', 'u', 'i', 'o', 'p', ' ő', 'ú',
'\\'),
('', 'a', 's', 'd', 'f', 'g', 'h', 'j', 'k', 'l', 'é', 'á', 'ű'),
('í', 'y', 'x', 'c', 'v', 'b', 'n', 'm', ',', '.', '-'),
('', '', '', ' ')),
(('§', "'", '"', '+', '!', '%', '/', '=', '(', ')', 'Ö', 'Ü', 'Ó'),
('', 'Q', 'W', 'E', 'R', 'T', 'Z', 'U', 'I', 'O', 'P', 'Ő', 'Ú', ''),
('', 'A', 'S', 'D', 'F', 'G', 'H', 'J', 'K', 'L', 'É', 'Á', 'Ű'),
('Í', 'Y', 'X', 'C', 'V', 'B', 'N', 'M', '?', ':', '_'),
('', '', '', ' ')),
(('', '~', 'ˇ', '^', '˘', '°', '˛', '`', '˙', '´', '˝', '¨', '¸'),
('', '\\', '|', '', '', '', '', '€', '', '', '', '÷', '×', ''),
('', '', 'đ', 'Đ', '[', ']', '', '', 'ł', 'Ł', '$', 'ß', '¤'),
('<', '>', '#', '&', '@', '{', '}', '', ';', '>', '*'),
('', '', '', ' '))
)} # type: Dict[str, Tuple[Tuple[Tuple[str, ...], ...], ...]]
# fmt: on
def __init__(
self,
metric: str = 'euclidean',
cost: Tuple[float, float, float, float] = (1.0, 1.0, 0.5, 0.5),
layout: str = 'QWERTY',
failsafe: bool = False,
**kwargs: Any
):
"""Initialize Typo instance.
Parameters
----------
metric : str
Supported values include: ``euclidean``, ``manhattan``,
``log-euclidean``, and ``log-manhattan``
cost : tuple
A 4-tuple representing the cost of the four possible edits:
inserts, deletes, substitutions, and shift, respectively (by
default: (1, 1, 0.5, 0.5)) The substitution & shift costs should be
significantly less than the cost of an insertion & deletion unless
a log metric is used.
layout : str
Name of the keyboard layout to use (Currently supported:
``QWERTY``, ``Dvorak``, ``AZERTY``, ``QWERTZ``, ``auto``). If
``auto`` is selected, the class will attempt to determine an
appropriate keyboard based on the supplied words.
failsafe : bool
If True, substitution of an unknown character (one not present on
the selected keyboard) will incur a cost equal to an insertion plus
a deletion.
**kwargs
Arbitrary keyword arguments
.. versionadded:: 0.4.0
"""
super(Typo, self).__init__(**kwargs)
self._metric = metric
self._cost = cost
self._layout = layout
self._failsafe = failsafe
def dist_abs(self, src: str, tar: str) -> float:
"""Return the typo distance between two strings.
Parameters
----------
src : str
Source string for comparison
tar : str
Target string for comparison
Returns
-------
float
Typo distance
Raises
------
ValueError
char not found in any keyboard layouts
Examples
--------
>>> cmp = Typo()
>>> cmp.dist_abs('cat', 'hat')
1.5811388300841898
>>> cmp.dist_abs('Niall', 'Neil')
2.8251407699364424
>>> cmp.dist_abs('Colin', 'Cuilen')
3.414213562373095
>>> cmp.dist_abs('ATCG', 'TAGC')
2.5
>>> cmp = Typo(metric='manhattan')
>>> cmp.dist_abs('cat', 'hat')
2.0
>>> cmp.dist_abs('Niall', 'Neil')
3.0
>>> cmp.dist_abs('Colin', 'Cuilen')
3.5
>>> cmp.dist_abs('ATCG', 'TAGC')
2.5
>>> cmp = Typo(metric='log-manhattan')
>>> cmp.dist_abs('cat', 'hat')
0.8047189562170501
>>> cmp.dist_abs('Niall', 'Neil')
2.2424533248940004
>>> cmp.dist_abs('Colin', 'Cuilen')
2.242453324894
>>> cmp.dist_abs('ATCG', 'TAGC')
2.3465735902799727
.. versionadded:: 0.3.0
.. versionchanged:: 0.3.6
Encapsulated in class
"""
ins_cost, del_cost, sub_cost, shift_cost = self._cost
if src == tar:
return 0.0
if not src:
return len(tar) * ins_cost
if not tar:
return len(src) * del_cost
if self._layout == 'auto':
for kb in ['QWERTY', 'QWERTZ', 'AZERTY']:
keys = set(chain(*chain(*self._keyboard[kb])))
letters = set(src) | set(tar)
if not (letters - keys):
keyboard = self._keyboard[kb]
break
else:
# Fallback to QWERTY
keyboard = self._keyboard['QWERTY']
else:
keyboard = self._keyboard[self._layout]
kb_array = []
for kb_mode in keyboard:
kb_array.append({item for sublist in kb_mode for item in sublist})
keys = set(chain(*chain(*keyboard)))
def _kb_array_for_char(char: str) -> Tuple[Tuple[str, ...], ...]:
"""Return the keyboard layout that contains ch.
Parameters
----------
char : str
The character to lookup
Returns
-------
tuple
A keyboard
Raises
------
ValueError
char not found in any keyboard layouts
.. versionadded:: 0.3.0
"""
for i, kb_mode in enumerate(kb_array):
if char in kb_mode:
return keyboard[i]
raise ValueError(char + ' not found in any keyboard layouts')
def _substitution_cost(char1: str, char2: str) -> float:
if self._failsafe and (char1 not in keys or char2 not in keys):
return ins_cost + del_cost
cost = sub_cost
cost *= metric_dict[self._metric](char1, char2) + shift_cost * (
_kb_array_for_char(char1) != _kb_array_for_char(char2)
)
return cost
def _get_char_coord(
char: str, kb_array: Tuple[Tuple[str, ...], ...]
) -> Tuple[int, int]:
"""Return the row & column of char in the keyboard.
Parameters
----------
char : str
The character to search for
kb_array : tuple of tuples
The array of key positions
Returns
-------
tuple
The row & column of the key
.. versionadded:: 0.3.0
"""
for row in kb_array: # pragma: no branch
if char in row:
break
return kb_array.index(row), row.index(char)
def _euclidean_keyboard_distance(char1: str, char2: str) -> float:
row1, col1 = _get_char_coord(char1, _kb_array_for_char(char1))
row2, col2 = _get_char_coord(char2, _kb_array_for_char(char2))
return ((row1 - row2) ** 2 + (col1 - col2) ** 2) ** 0.5
def _manhattan_keyboard_distance(char1: str, char2: str) -> float:
row1, col1 = _get_char_coord(char1, _kb_array_for_char(char1))
row2, col2 = _get_char_coord(char2, _kb_array_for_char(char2))
return abs(row1 - row2) + abs(col1 - col2)
def _log_euclidean_keyboard_distance(char1: str, char2: str) -> float:
return log(1 + _euclidean_keyboard_distance(char1, char2))
def _log_manhattan_keyboard_distance(char1: str, char2: str) -> float:
return log(1 + _manhattan_keyboard_distance(char1, char2))
metric_dict = {
'euclidean': _euclidean_keyboard_distance,
'manhattan': _manhattan_keyboard_distance,
'log-euclidean': _log_euclidean_keyboard_distance,
'log-manhattan': _log_manhattan_keyboard_distance,
}
d_mat = np_zeros((len(src) + 1, len(tar) + 1), dtype=np_float)
for i in range(len(src) + 1):
d_mat[i, 0] = i * del_cost
for j in range(len(tar) + 1):
d_mat[0, j] = j * ins_cost
for i in range(len(src)):
for j in range(len(tar)):
d_mat[i + 1, j + 1] = min(
d_mat[i + 1, j] + ins_cost, # ins
d_mat[i, j + 1] + del_cost, # del
d_mat[i, j]
+ (
_substitution_cost(src[i], tar[j])
if src[i] != tar[j]
else 0
), # sub/==
)
return cast(float, d_mat[len(src), len(tar)])
def dist(self, src: str, tar: str) -> float:
"""Return the normalized typo distance between two strings.
This is typo distance, normalized to [0, 1].
Parameters
----------
src : str
Source string for comparison
tar : str
Target string for comparison
Returns
-------
float
Normalized typo distance
Examples
--------
>>> cmp = Typo()
>>> round(cmp.dist('cat', 'hat'), 12)
0.527046276695
>>> round(cmp.dist('Niall', 'Neil'), 12)
0.565028153987
>>> round(cmp.dist('Colin', 'Cuilen'), 12)
0.569035593729
>>> cmp.dist('ATCG', 'TAGC')
0.625
.. versionadded:: 0.3.0
.. versionchanged:: 0.3.6
Encapsulated in class
"""
if src == tar:
return 0.0
ins_cost, del_cost = self._cost[:2]
return self.dist_abs(src, tar) / (
max(len(src) * del_cost, len(tar) * ins_cost)
)
if __name__ == '__main__':
import doctest
doctest.testmod()