Spell Checker for Python

I'm fairly new to Python and NLTK. I am busy with an application that can perform spell checks (replaces an incorrectly spelled word with the correct one). I'm currently using the Enchant library on Python 2.7, PyEnchant and the NLTK library. The code below is a class that handles the correction/replacement.

from nltk.metrics import edit_distance

class SpellingReplacer:
    def __init__(self, dict_name='en_GB', max_dist=2):
        self.spell_dict = enchant.Dict(dict_name)
        self.max_dist = 2

    def replace(self, word):
        if self.spell_dict.check(word):
            return word
        suggestions = self.spell_dict.suggest(word)

        if suggestions and edit_distance(word, suggestions[0]) <= self.max_dist:
            return suggestions[0]
        else:
            return word

I have written a function that takes in a list of words and executes replace() on each word and then returns a list of those words, but spelled correctly.

def spell_check(word_list):
    checked_list = []
    for item in word_list:
        replacer = SpellingReplacer()
        r = replacer.replace(item)
        checked_list.append(r)
    return checked_list

>>> word_list = ['car', 'colour']
>>> spell_check(words)
['car', 'color']

Now, I don't really like this because it isn't very accurate and I'm looking for a way to achieve spelling checks and replacements on words. I also need something that can pick up spelling mistakes like "caaaar"? Are there better ways to perform spelling checks out there? If so, what are they? How does Google do it? Because their spelling suggester is very good.

Any suggestions?

Solution 1:

You can use the autocorrect lib to spell check in python.
Example Usage:

from autocorrect import Speller

spell = Speller(lang='en')

print(spell('caaaar'))
print(spell('mussage'))
print(spell('survice'))
print(spell('hte'))

Result:

caesar
message
service
the

Solution 2:

I'd recommend starting by carefully reading this post by Peter Norvig. (I had to something similar and I found it extremely useful.)

The following function, in particular has the ideas that you now need to make your spell checker more sophisticated: splitting, deleting, transposing, and inserting the irregular words to 'correct' them.

def edits1(word):
   splits     = [(word[:i], word[i:]) for i in range(len(word) + 1)]
   deletes    = [a + b[1:] for a, b in splits if b]
   transposes = [a + b[1] + b[0] + b[2:] for a, b in splits if len(b)>1]
   replaces   = [a + c + b[1:] for a, b in splits for c in alphabet if b]
   inserts    = [a + c + b     for a, b in splits for c in alphabet]
   return set(deletes + transposes + replaces + inserts)

Note: The above is one snippet from Norvig's spelling corrector

And the good news is that you can incrementally add to and keep improving your spell-checker.

Hope that helps.

Solution 3:

The best way for spell checking in python is by: SymSpell, Bk-Tree or Peter Novig's method.

The fastest one is SymSpell.

This is Method1: Reference link pyspellchecker

This library is based on Peter Norvig's implementation.

pip install pyspellchecker

from spellchecker import SpellChecker

spell = SpellChecker()

# find those words that may be misspelled
misspelled = spell.unknown(['something', 'is', 'hapenning', 'here'])

for word in misspelled:
    # Get the one `most likely` answer
    print(spell.correction(word))

    # Get a list of `likely` options
    print(spell.candidates(word))

Method2: SymSpell Python

pip install -U symspellpy