classes.py

#!/usr/bin/python3
# -*- coding: utf-8 -*-

import collections


# CaseInsensitiveDict class inherited from dict
class CaseInsensitiveDict(dict):
    """Basic case insensitive dict with strings only keys."""

    proxy = {}

    def __init__(self, data):
        self.proxy = dict((k.lower(), k) for k in data)
        for k in data:
            self[k] = data[k]

    def __contains__(self, k):
        return k.lower() in self.proxy

    def __delitem__(self, k):
        key = self.proxy[k.lower()]
        super(CaseInsensitiveDict, self).__delitem__(key)
        del self.proxy[k.lower()]

    def __getitem__(self, k):
        key = self.proxy[k.lower()]
        return super(CaseInsensitiveDict, self).__getitem__(key)

    def get(self, k, default=None):
        return self[k] if k in self else default

    def __setitem__(self, k, v):
        super(CaseInsensitiveDict, self).__setitem__(k, v)
        self.proxy[k.lower()] = k


class SpellingCorrector:
    """
    Spelling Corrector in Python 3; see http://norvig.com/spell-correct.html
    Copyright (c) 2007-2016 Peter Norvig
    MIT license: www.opensource.org/licenses/mit-license.php
    """

    word_list = []
    WORDS = collections.Counter([])

    def __init__(self, words):
        self.word_list = [t.lower() for t in words]
        self.WORDS = collections.Counter(self.word_list)

    def P(self, word, N=sum(WORDS.values())):
        "Probability of `word`."
        if N == 0:
            return 0
        return self.WORDS[word] / N

    def correction(self, word):
        "Most probable spelling correction for word."
        return max(self.candidates(word), key=self.P)

    def candidates(self, word):
        "Generate possible spelling corrections for word."
        return (
            self.known([word])
            or self.known(self.edits1(word))
            or self.known(self.edits2(word))
            or [word]
        )

    def known(self, words):
        "The subset of `words` that appear in the dictionary of WORDS."
        return set(w for w in words if w in self.WORDS)

    def edits1(self, word):
        "All edits that are one edit away from `word`."

        letters = "abcdefghijklmnopqrstuvwxyz"
        splits = [(word[:i], word[i:]) for i in range(len(word) + 1)]
        deletes = [L + R[1:] for L, R in splits if R]
        transposes = [L + R[1] + R[0] + R[2:] for L, R in splits if len(R) > 1]
        replaces = [L + c + R[1:] for L, R in splits if R for c in letters]
        inserts = [L + c + R for L, R in splits for c in letters]

        return set(deletes + transposes + replaces + inserts)

    def edits2(self, word):
        "All edits that are two edits away from `word`."

        return (e2 for e1 in self.edits1(word) for e2 in self.edits1(e1))