com.johnsnowlabs.nlp.annotators.spell.common.LevenshteinDistance.scala Maven / Gradle / Ivy

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package com.johnsnowlabs.nlp.annotators.spell.common

import scala.math.min

trait LevenshteinDistance {


  /** Computes Levenshtein distance :
    * Metric of measuring difference between two sequences (edit distance)
    * Source: https://rosettacode.org/wiki/Levenshtein_distance
    * */

  def levenshteinDistance(s1: String, s2: String): Int = {
    val dist = Array.tabulate(s2.length + 1, s1.length + 1) { (j, i) => if (j == 0) i else if (i == 0) j else 0 }

    for (j <- 1 to s2.length; i <- 1 to s1.length)
      dist(j)(i) = if (s2(j - 1) == s1(i - 1)) dist(j - 1)(i - 1)
      else minimum(dist(j - 1)(i) + 1, dist(j)(i - 1) + 1, dist(j - 1)(i - 1) + 1)

    dist(s2.length)(s1.length)
  }

  private def minimum(i1: Int, i2: Int, i3: Int) = min(min(i1, i2), i3)


}