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magicrebirth on 01/09/11

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# How to Write a Spelling Corrector (in 21 lines)

/ Published in: Python  Requires an external file for the statistical algorithm... (big.txt)

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`import re, collections def words(text): return re.findall('[a-z]+', text.lower())  def train(features):    model = collections.defaultdict(lambda: 1)    for f in features:        model[f] += 1    return model NWORDS = train(words(file('big.txt').read())) alphabet = 'abcdefghijklmnopqrstuvwxyz' 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 + b + 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) def known_edits2(word):    return set(e2 for e1 in edits1(word) for e2 in edits1(e1) if e2 in NWORDS) def known(words): return set(w for w in words if w in NWORDS) def correct(word):    candidates = known([word]) or known(edits1(word)) or known_edits2(word) or [word]    return max(candidates, key=NWORDS.get)` Subscribe to comments