71 lines
1.8 KiB
V
71 lines
1.8 KiB
V
module strings
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// #-js
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// use levenshtein distance algorithm to calculate
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// the distance between between two strings (lower is closer)
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pub fn levenshtein_distance(a, b string) int {
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mut f := [0].repeat(b.len + 1)
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for j in 0..f.len {
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f[j] = j
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}
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for ca in a {
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mut j := 1
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mut fj1 := f[0]
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f[0]++
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for cb in b {
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mut mn := if f[j] + 1 <= f[j - 1] + 1 { f[j] + 1 } else { f[j - 1] + 1 }
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if cb != ca {
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mn = if mn <= fj1 + 1 { mn } else { fj1 + 1 }
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}
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else {
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mn = if mn <= fj1 { mn } else { fj1 }
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}
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fj1 = f[j]
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f[j] = mn
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j++
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}
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}
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return f[f.len - 1]
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}
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// use levenshtein distance algorithm to calculate
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// how similar two strings are as a percentage (higher is closer)
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pub fn levenshtein_distance_percentage(a, b string) f32 {
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d := levenshtein_distance(a, b)
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l := if a.len >= b.len { a.len } else { b.len }
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return (1.00 - f32(d) / f32(l)) * 100.00
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}
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// implementation of Sørensen–Dice coefficient.
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// find the similarity between two strings.
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// returns coefficient between 0.0 (not similar) and 1.0 (exact match).
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pub fn dice_coefficient(s1, s2 string) f32 {
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if s1.len == 0 || s2.len == 0 {
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return 0.0
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}
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if s1 == s2 {
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return 1.0
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}
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if s1.len < 2 || s2.len < 2 {
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return 0.0
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}
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a := if s1.len > s2.len { s1 } else { s2 }
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b := if a == s1 { s2 } else { s1 }
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mut first_bigrams := map[string]int
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for i in 0..a.len - 1 {
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bigram := a[i..i + 2]
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q := if bigram in first_bigrams { first_bigrams[bigram] + 1 } else { 1 }
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first_bigrams[bigram] = q
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}
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mut intersection_size := 0
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for i in 0..b.len - 1 {
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bigram := b[i..i + 2]
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count := if bigram in first_bigrams { first_bigrams[bigram] } else { 0 }
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if count > 0 {
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first_bigrams[bigram] = count - 1
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intersection_size++
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}
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}
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return (2.0 * intersection_size) / (f32(a.len) + f32(b.len) - 2)
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}
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