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AutoHotkey: StrDiff()
/*
By Toralf:
Forum thread: http://www.autohotkey.com/forum/topic59407.html
Basic idea for SIFT3 code by Siderite Zackwehdex
http://siderite.blogspot.com/2007/04/super-fast-and-accurate-string-distance.html
Took idea to normalize it to longest string from Brad Wood
http://www.bradwood.com/string_compare/
Own work:
- when character only differ in case, LSC is a 0.8 match for this character
- modified code for speed, might lead to different results compared to original code
- optimized for speed (30% faster then original SIFT3 and 13.3 times faster than basic Levenshtein distance)
*/
StrDiff(str1, str2, maxOffset:=5) {
if (str1 = str2)
return (str1 == str2 ? 0/1 : 0.2/StrLen(str1))
if (str1 = "" || str2 = "")
return (str1 = str2 ? 0/1 : 1/1)
StringSplit, n, str1
StringSplit, m, str2
ni := 1, mi := 1, lcs := 0
while ((ni <= n0) && (mi <= m0)) {
if (n%ni% == m%mi%)
lcs += 1
else if (n%ni% = m%mi%)
lcs += 0.8
else {
Loop, % maxOffset {
oi := ni + A_Index, pi := mi + A_Index
if ((n%oi% = m%mi%) && (oi <= n0)) {
ni := oi, lcs += (n%oi% == m%mi% ? 1 : 0.8)
break
}
if ((n%ni% = m%pi%) && (pi <= m0)) {
mi := pi, lcs += (n%ni% == m%pi% ? 1 : 0.8)
break
}
}
}
ni += 1
mi += 1
}
return ((n0 + m0)/2 - lcs) / (n0 > m0 ? n0 : m0)
}
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