Search results
Results from the WOW.Com Content Network
In mathematics and computer science, a string metric (also known as a string similarity metric or string distance function) is a metric that measures distance ("inverse similarity") between two text strings for approximate string matching or comparison and in fuzzy string searching.
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).
It is at most the length of the longer string. It is zero if and only if the strings are equal. If the strings have the same size, the Hamming distance is an upper bound on the Levenshtein distance. The Hamming distance is the number of positions at which the corresponding symbols in the two strings are different.
When taken as a string similarity measure, the coefficient may be calculated for two strings, x and y using bigrams as follows: [11] = + where n t is the number of character bigrams found in both strings, n x is the number of bigrams in string x and n y is the number of bigrams in string y. For example, to calculate the similarity between:
Presented here are two algorithms: the first, [8] simpler one, computes what is known as the optimal string alignment distance or restricted edit distance, [7] while the second one [9] computes the Damerau–Levenshtein distance with adjacent transpositions. Adding transpositions adds significant complexity.
A similar algorithm for approximate string matching is the bitap algorithm, also defined in terms of edit distance. Levenshtein automata are finite-state machines that recognize a set of strings within bounded edit distance of a fixed reference string.
The similarity of two strings and is determined by this formula: twice the number of matching characters divided by the total number of characters of both strings. The matching characters are defined as some longest common substring [3] plus recursively the number of matching characters in the non-matching regions on both sides of the longest common substring: [2] [4]
In statistics and related fields, a similarity measure or similarity function or similarity metric is a real-valued function that quantifies the similarity between two objects. Although no single definition of a similarity exists, usually such measures are in some sense the inverse of distance metrics : they take on large values for similar ...