超越PHP - Exceed PHP: levenshtein

Description

int levenshtein ( string str1, string str2 [, int cost_ins [, int cost_rep, int cost_del]])

This function returns the Levenshtein-Distance between the two argument strings or -1, if one of the argument strings is longer than the limit of 255 characters (255 should be more than enough for name or dictionary comparison, and nobody serious would be doing genetic analysis with PHP).

The Levenshtein distance is defined as the minimal number of characters you have to replace, insert or delete to transform str1 into str2. The complexity of the algorithm is O(m*n), where n and m are the length of str1 and str2 (rather good when compared to similar_text(), which is O(max(n,m)**3), but still expensive).

In its simplest form the function will take only the two strings as parameter and will calculate just the number of insert, replace and delete operations needed to transform str1 into str2.

A second variant will take three additional parameters that define the cost of insert, replace and delete operations. This is more general and adaptive than variant one, but not as efficient.

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levenshtein

ad1n at dc dot uba dot ar
05-Aug-2000 08:01

One application of this is when you want to look for a similar match
instead of an exact one. You can sort the results of checking the distances
of a word to a dictionary and sort them to see which were the more similar
ones. Of course it will be a quite resourse consuming task anyway.

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