Steven She at woggie.net

public class SpellingCorrector {
  def wordoccur = [:]
 
  def words(File file) {
    Scanner scanner = new Scanner(file)
    def words = scanner.findAll{ x -> x.toLowerCase() ==~ ~/[a-z]+/  }
  }
 
  def train(List words) {
    words.each {
      wordoccur[it] = wordoccur.containsKey(it) ? wordoccur[it] + 1 : 1
    }
  }
 
  def edits1(String word) {
    def results = []
    int n = word.length()
    //Deletion. Remove a character.
    for (i in 0..<n)
      results << word[0..<i] + word[i+1..<n]
 
    //Transposition. Swap adjacent characters.
    for (i in 0..<n-1)
      results << word[0..<i] + word[i+1] + word[i] + word[i+2..<n]
 
    //Alteration. Change one character for another letter.
    for (i in 0..<n)
      for (c in 'a'..'z')
        results << word[0..<i] + c + word[i+1..<n]
 
    //Insertion. Add a letter in between the others.
    for (i in 0..<n)
      for (c in 'a'..'z')
        results << word[0..<i] + c + word[i+1..<n]
 
    return results
  }
 
  def knownedits2(String word) {
    def candidates = []
    edits1(word).each {
      candidates.addAll( edits1(it).findAll { wordoccur.containsKey(it) } )
    }
    return candidates
  }
 
  /**
   * Smoothing distribution. If the word hasn't been encountered (novel words),
   *  we give it an occurence value of 1.
   */
  def int occurrence(String word) {
    return wordoccur[word] == null ? 1 : wordoccur[word];  
  }
 
  def List known(List words) {
    return words.findAll { wordoccur.containsKey(it.toLowerCase()) }
  }
 
  def correct(String word) {
    def candidates = [word] + known([word]) + known(edits1(word)) + knownedits2(word)
    return candidates.max {  occurrence(it) }
  }
}