55 lines
2.2 KiB
Java
55 lines
2.2 KiB
Java
package calcul;
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public class StringSimilarity {
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/**
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* Calculates the similarity (a number within 0 and 1) between two strings.
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*/
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public static double similarity(String s1, String s2) {
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String longer = s1, shorter = s2;
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if (s1.length() < s2.length()) { // longer should always have greater length
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longer = s2; shorter = s1;
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}
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int longerLength = longer.length();
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if (longerLength == 0) { return 1.0; /* both strings are zero length */ }
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/* // If you have StringUtils, you can use it to calculate the edit distance:
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return (longerLength - StringUtils.getLevenshteinDistance(longer, shorter)) /
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(double) longerLength; */
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return (longerLength - editDistance(longer, shorter)) / (double) longerLength;
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}
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// Example implementation of the Levenshtein Edit Distance
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// See http://r...content-available-to-author-only...e.org/wiki/Levenshtein_distance#Java
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public static int editDistance(String s1, String s2) {
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s1 = s1.toLowerCase();
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s2 = s2.toLowerCase();
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int[] costs = new int[s2.length() + 1];
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for (int i = 0; i <= s1.length(); i++) {
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int lastValue = i;
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for (int j = 0; j <= s2.length(); j++) {
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if (i == 0)
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costs[j] = j;
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else {
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if (j > 0) {
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int newValue = costs[j - 1];
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if (s1.charAt(i - 1) != s2.charAt(j - 1))
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newValue = Math.min(Math.min(newValue, lastValue),
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costs[j]) + 1;
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costs[j - 1] = lastValue;
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lastValue = newValue;
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}
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}
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}
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if (i > 0)
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costs[s2.length()] = lastValue;
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}
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return costs[s2.length()];
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}
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public static void printSimilarity(String s, String t) {
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System.out.println(String.format(
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"%.3f is the similarity between \"%s\" and \"%s\"", similarity(s, t), s, t));
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}
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}
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