Copyright	© 2016 Mark Karpov
License	BSD 3 clause
Maintainer	Mark Karpov <[email protected]>
Stability	experimental
Portability	portable
Safe Haskell	None
Language	Haskell2010

Data.Text.Metrics

Contents

Levenshtein variants
Other

Description

The module provides efficient implementations of various strings metrics. It works with strict Text values and returns either Natural numbers (because the metrics cannot be negative), or Ratio Natural values because returned values are rational non-negative numbers by definition.

Synopsis

Levenshtein variants

levenshtein :: Text -> Text -> Natural Source #

Return Levenshtein distance between two Text values. Classic Levenshtein distance between two strings is minimal number of operations necessary to transform one string into another. For Levenshtein distance allowed operations are: deletion, insertion, and substitution.

levenshteinNorm :: Text -> Text -> Ratio Natural Source #

Return normalized Levenshtein distance between two Text values. Result is a non-negative rational number (represented as Ratio Natural), where 0 signifies no similarity between the strings, while 1 means exact match. The operation is virtually as fast as levenshtein.

damerauLevenshtein :: Text -> Text -> Natural Source #

Return Damerau-Levenshtein distance between two Text values. The function works like levenshtein, but the collection of allowed operations also includes transposition of two adjacent characters. The function is about 20% slower than levenshtein, but still pretty fast.

damerauLevenshteinNorm :: Text -> Text -> Ratio Natural Source #

Return normalized Damerau-Levenshtein distance between two Text values. Result is a non-negative rational number (represented as Ratio Natural), where 0 signifies no similarity between the strings, while 1 means exact match. The operation is virtually as fast as damerauLevenshtein.

Other

hamming :: Text -> Text -> Maybe Natural Source #

O(n) Return Hamming distance between two Text values. Hamming distance is defined as number of positions at which the corresponding symbols are different. The input Text values should be of equal length or Nothing will be returned.