Jaro–Winkler distance

In computer science and statistics, the Jaro–Winkler similarity is a string metric measuring an edit distance between two sequences. It is a variant of the Jaro distance metric metric (1989, Matthew A. Jaro) proposed in 1990 by William E. Winkler.

The Jaro–Winkler distance uses a prefix scale ${\displaystyle p}$ which gives more favourable ratings to strings that match from the beginning for a set prefix length ${\displaystyle \ell }$.

The higher the Jaro–Winkler distance for two strings is, the less similar the strings are. The score is normalized such that 0 means an exact match and 1 means there is no similarity. The original paper actually defined the metric in terms of similarity, so the distance is defined as the inversion of that value (distance = 1 − similarity).

Although often referred to as a distance metric, the Jaro–Winkler distance is not a metric in the mathematical sense of that term because it does not obey the triangle inequality.