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72 lines
1.6 KiB
Go
72 lines
1.6 KiB
Go
// Package levenshtein is a Go implementation to calculate Levenshtein Distance.
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//
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// Implementation taken from
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// https://gist.github.com/andrei-m/982927#gistcomment-1931258
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package levenshtein
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// ComputeDistance computes the levenshtein distance between the two
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// strings passed as an argument. The return value is the levenshtein distance
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//
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// Works on runes (Unicode code points) but does not normalize
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// the input strings. See https://blog.golang.org/normalization
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// and the golang.org/x/text/unicode/norm pacage.
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func ComputeDistance(a, b string) int {
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if a == b {
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return 0
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}
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// We need to convert to []rune if the strings are non-ascii.
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// This could be avoided by using utf8.RuneCountInString
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// and then doing some juggling with rune indices.
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// The primary challenge is keeping track of the previous rune.
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// With a range loop, its not that easy. And with a for-loop
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// we need to keep track of the inter-rune width using utf8.DecodeRuneInString
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s1 := []rune(a)
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s2 := []rune(b)
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// swap to save some memory O(min(a,b)) instead of O(a)
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if len(s1) > len(s2) {
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s1, s2 = s2, s1
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}
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lenS1 := len(s1)
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lenS2 := len(s2)
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// init the row
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x := make([]int, lenS1+1)
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for i := 0; i <= lenS1; i++ {
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x[i] = i
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}
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// fill in the rest
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for i := 1; i <= lenS2; i++ {
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prev := i
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var current int
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for j := 1; j <= lenS1; j++ {
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if s2[i-1] == s1[j-1] {
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current = x[j-1] // match
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} else {
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current = min(x[j-1]+1, prev+1, x[j]+1)
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}
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x[j-1] = prev
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prev = current
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}
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x[lenS1] = prev
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}
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return x[lenS1]
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}
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func min(a, b, c int) int {
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if a < b {
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if a < c {
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return a
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}
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} else {
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if b < c {
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return b
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}
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}
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return c
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}
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