com.github.vickumar1981.stringdistance.impl.NGramImpl.scala Maven / Gradle / Ivy

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A fuzzy matching string distance library for Scala and Java.

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package com.github.vickumar1981.stringdistance.impl

import com.github.vickumar1981.stringdistance.interfaces.NGramTokenizer

private[stringdistance] trait NGramImpl extends NGramTokenizer {
  protected def nGram[T](s1: Array[T], s2: Array[T], n: Int = 1): Double = {
    require(n > 0, "Ngram score, n-gram size must be a positive number.")
    foldNGram(s1, s2, n)(0d)(_ => 1d) { (s1Tok, s2Tok, dist) =>
      dist.toDouble / math.max(s1Tok.length, s2Tok.length)
    }
  }

  protected def nGramDist[T](s1: Array[T], s2: Array[T], n: Int = 1): Int = {
    require(n > 0, "Ngram distance, n-gram size must be a positive number.")
    foldNGram(s1, s2, n)(0)(identity) { (_, _, dist) => dist }
  }
}