Interface SMStringLevenshtein

All Superinterfaces:
SimilarityMeasure, SMString
All Known Implementing Classes:

public interface SMStringLevenshtein extends SMString
Compares two strings using the Levenshtein algorithm. The comparison can be case-sensitive or insensitive.

Levenshtein distance (LD) is a measure of the similarity between two strings, which we will refer to as the source string (s) and the target string (t). The distance is the number of deletions, insertions, or substitutions required to transform s into t. For example,

  • If s is "test" and t is "test", then LD(s,t) = 0, because no transformations are needed. The strings are already identical.
  • If s is "test" and t is "tent", then LD(s,t) = 1, because one substitution (change "s" to "n") is sufficient to transform s into t.

The greater the Levenshtein distance, the more different the strings are. The Worst case is O(nd)-time, average case O(n+d2)-time algorithm for edit-distance, where d is the edit-distance between the two strings.

Levenshtein distance is named after the Russian scientist Vladimir Levenshtein, who devised the algorithm in 1965. If you can't spell or pronounce Levenshtein, the metric is also sometimes called edit distance.


The similarity between s and t is defined as sim(s,t) = LD(s,t) / max(length(s),length(t))

Online References

Other discussions of Levenshtein distance are:

Paper References

  • V. I. Levenshtein. Binary codes capable of correcting deletions, insertions and reversals. Doklady Akademii Nauk SSSR 163(4) p845-848, 1965, also Soviet Physics Doklady 10(8) p707-710, Feb 1966.
    Discovered the basic DPA for edit distance.
  • S. B. Needleman and C. D. Wunsch. A general method applicable to the search for similarities in the amino acid sequence of two proteins. Jrnl Molec. Biol. 48 p443-453, 1970.
    Defined a similarity score on molecular-biology sequences, with an O(n2) algorithm that is closely related to those discussed here.
  • Hirschberg (1975) presented a method of recovering an alignment (of an LCS) in O(n2) time but in only linear, O(n)-space; see [here].
  • E. Ukkonen On approximate string matching. Proc. Int. Conf. on Foundations of Comp. Theory, Springer-Verlag, LNCS 158 p487-495, 1983.
Rainer Maximini
  • Field Details

    • NAME

      static final String NAME
      Name of similarity measure is "StringLevenshtein".
      See Also:

      static final boolean DEFAULT_CASE_SENSITIVE
      The default value for case sensitive is true.
      See Also:

      static final int DEFAULT_THRESHOLD
      The default threshold value is -1.
      See Also:
  • Method Details

    • isCaseInsensitive

      boolean isCaseInsensitive()
    • isCaseSensitive

      boolean isCaseSensitive()
    • setCaseInsensitive

      void setCaseInsensitive()
    • setCaseSensitive

      void setCaseSensitive()
    • getThreshold

      int getThreshold()
    • setThreshold

      void setThreshold(int threshold)