mirror of https://github.com/kepler155c/opus
57 lines
1.1 KiB
Lua
57 lines
1.1 KiB
Lua
local find = string.find
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local floor = math.floor
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local min = math.min
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local max = math.max
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local sub = string.sub
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-- https://rosettacode.org/wiki/Jaro_distance (ported to lua)
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return function(s1, s2)
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local l1, l2 = #s1, #s2;
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if l1 == 0 then
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return l2 == 0 and 1.0 or 0.0
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end
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local match_distance = max(floor(max(l1, l2) / 2) - 1, 0)
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local s1_matches = { }
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local s2_matches = { }
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local matches = 0
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for i = 1, l1 do
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local _end = min(i + match_distance + 1, l2)
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for k = max(1, i - match_distance), _end do
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if not s2_matches[k] and sub(s1, i, i) == sub(s2, k, k) then
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s1_matches[i] = true
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s2_matches[k] = true
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matches = matches + 1
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break
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end
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end
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end
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if matches == 0 then
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return 0.0
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end
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local t = 0.0
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local k = 1
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for i = 1, l1 do
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if s1_matches[i] then
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while not s2_matches[k] do
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k = k + 1
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end
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if sub(s1, i, i) ~= sub(s2, k, k) then
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t = t + 0.5
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end
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k = k + 1
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end
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end
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-- provide a major boost for exact matches
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local b = 0.0
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if find(s1, s2, 1, true) then
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b = b + .5
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end
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local m = matches
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return (m / l1 + m / l2 + (m - t) / m) / 3.0 + b
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end
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