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minio/damerau-levenshtein.go

66 lines
1.6 KiB

/*
* Minio Client (C) 2014-2016 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package main
import (
"math"
)
// Returns the minimum value of a slice of integers
func minimum(integers []int) (minVal int) {
minVal = math.MaxInt32
for _, v := range integers {
if v < minVal {
minVal = v
}
}
return
}
// DamerauLevenshteinDistance calculates distance between two strings using an algorithm
// described in https://en.wikipedia.org/wiki/Damerau-Levenshtein_distance
func DamerauLevenshteinDistance(a string, b string) int {
d := make([][]int, len(a)+1)
for i := 1; i <= len(a)+1; i++ {
d[i-1] = make([]int, len(b)+1)
}
for i := 0; i <= len(a); i++ {
d[i][0] = i
}
for j := 0; j <= len(b); j++ {
d[0][j] = j
}
for i := 1; i <= len(a); i++ {
for j := 1; j <= len(b); j++ {
cost := 0
if a[i-1] == b[j-1] {
cost = 0
} else {
cost = 1
}
d[i][j] = minimum([]int{
d[i-1][j] + 1,
d[i][j-1] + 1,
d[i-1][j-1] + cost,
})
if i > 1 && j > 1 && a[i-1] == b[j-2] && a[i-2] == b[j-1] {
d[i][j] = minimum([]int{d[i][j], d[i-2][j-2] + cost}) // transposition
}
}
}
return d[len(a)][len(b)]
}