File size: 4,058 Bytes
e4b9a7b
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
# -*- coding: utf-8 -*-
# SPDX-FileCopyrightText: 2016-2025 PyThaiNLP Project
# SPDX-FileType: SOURCE
# SPDX-License-Identifier: Apache-2.0
from typing import List

import numpy as np

THAI_CHARACTERS_WITHOUT_SHIFT = [
    "ผปแอิืทมใฝ",
    "ฟหกดเ้่าสวง",
    "ๆไำพะัีรนยบลฃ",
    "ๅ/_ภถุึคตจขช",
]

THAI_CHARACTERS_WITH_SHIFT = [
    "()ฉฮฺ์?ฒฬฦ",
    "ฤฆฏโฌ็๋ษศซ.",
    '๐"ฎฑธํ๊ณฯญฐ,',
    "+๑๒๓๔ู฿๕๖๗๘๙",
]

ENGLISH_CHARACTERS_WITHOUT_SHIFT = [
    "1234567890-=",
    "qwertyuiop[]\\",
    "asdfghjkl;'",
    "zxcvbnm,./",
]

ENGLISH_CHARACTERS_WITH_SHIFT = [
    "!@#$%^&*()_+",
    "QWERTYUIOP{}|",
    'ASDFGHJKL:"',
    "ZXCVBNM<>?",
]


ALL_CHARACTERS = [
    THAI_CHARACTERS_WITHOUT_SHIFT + THAI_CHARACTERS_WITH_SHIFT,
    ENGLISH_CHARACTERS_WITHOUT_SHIFT + ENGLISH_CHARACTERS_WITH_SHIFT,
]


def search_location_of_character(char: str):
    for language_ix in [0, 1]:
        for ix, row in enumerate(ALL_CHARACTERS[language_ix]):
            if char in row:
                return (language_ix, ix // 4, ix % 4, row.index(char))


def find_neighbour_locations(
    loc: tuple,
    char: str,
    kernel: List = [(-1, -1), (-1, 0), (1, 1), (0, 1), (0, -1), (1, 0)],
):
    language_ix, is_shift, row, pos = loc

    valid_neighbours = []
    for kr, ks in kernel:
        _row, _pos = row + kr, pos + ks
        if 0 <= _row <= 3 and 0 <= _pos <= len(
            ALL_CHARACTERS[language_ix][is_shift * 4 + _row]
        ):
            valid_neighbours.append((language_ix, is_shift, _row, _pos, char))

    return valid_neighbours


def find_misspell_candidates(char: str, verbose: bool = False):
    loc = search_location_of_character(char)
    if loc is None:
        return None

    valid_neighbours = find_neighbour_locations(loc, char)

    chars = []
    printing_locations = ["▐"] * 3 + [char] + ["▐"] * 3

    for language_ix, is_shift, row, pos, char in valid_neighbours:
        try:
            char = ALL_CHARACTERS[language_ix][is_shift * 4 + row][pos]
            chars.append(char)
            kernel = (row - loc[1], pos - loc[2])

            if kernel == (-1, -1):
                ix = 5
            elif kernel == (-1, 0):
                ix = 6
            elif kernel[0] == 0:
                ix = 3 + kernel[1]
            elif kernel == (1, 0):
                ix = 0
            elif kernel == (1, 1):
                ix = 1
            else:
                continue
            printing_locations[ix] = char
        except IndexError:
            continue
        except Exception as e:
            print("Something wrong with: ", char)
            raise e

    return chars


def misspell(sentence: str, ratio: float = 0.05):
    """
    Simulate some misspellings of the input sentence.
    The number of misspelled locations is governed by ratio.

    :params str sentence: sentence to be misspelled
    :params float ratio: number of misspells per 100 chars. Defaults to 0.5.

    :return: sentence containing some misspelled words
    :rtype: str

    :Example:
    ::

        from pythainlp.tools.misspell import misspell

        sentence = "ภาษาไทยปรากฏครั้งแรกในพุทธศักราช 1826"

        misspell(sent, ratio=0.1)
        # output:
        ภาษาไทยปรากฏครั้งแรกในกุทธศักราช 1727
    """
    num_misspells = np.floor(len(sentence) * ratio).astype(int)
    positions = np.random.choice(
        len(sentence), size=num_misspells, replace=False
    )

    # convert strings to array of characters
    misspelled = list(sentence)
    for pos in positions:
        potential_candidates = find_misspell_candidates(sentence[pos])
        if potential_candidates is None:
            continue

        candidate = np.random.choice(potential_candidates)

        misspelled[pos] = candidate

    return "".join(misspelled)