多くのライブラリで使用されているように、2つの文字列間の類似性を0%-100%の方法で計算する一般的な方法は、長い文字列を短い文字列に変換するためにどれだけ(%)変更する必要があるかを測定することです。
/**
* Calculates the similarity (a number within 0 and 1) between two strings.
*/
public static double similarity(String s1, String s2) {
String longer = s1, shorter = s2;
if (s1.length() < s2.length()) { // longer should always have greater length
longer = s2; shorter = s1;
}
int longerLength = longer.length();
if (longerLength == 0) { return 1.0; /* both strings are zero length */ }
return (longerLength - editDistance(longer, shorter)) / (double) longerLength;
}
// you can use StringUtils.getLevenshteinDistance() as the editDistance() function
// full copy-paste working code is below
の計算editDistance()
:
上記のeditDistance()
関数は、2つの文字列間の編集距離を計算することが期待されています。このステップにはいくつかの実装があり、それぞれが特定のシナリオにより適している場合があります。最も一般的なのはレーベンシュタイン距離アルゴリズムであり、以下の例ではそれを使用します(非常に大きな文字列の場合、他のアルゴリズムの方がパフォーマンスがよくなる可能性があります)。
編集距離を計算する2つのオプションは次のとおりです。
作業例:
こちらのオンラインデモをご覧ください。
public class StringSimilarity {
/**
* Calculates the similarity (a number within 0 and 1) between two strings.
*/
public static double similarity(String s1, String s2) {
String longer = s1, shorter = s2;
if (s1.length() < s2.length()) { // longer should always have greater length
longer = s2; shorter = s1;
}
int longerLength = longer.length();
if (longerLength == 0) { return 1.0; /* both strings are zero length */ }
/* // If you have Apache Commons Text, you can use it to calculate the edit distance:
LevenshteinDistance levenshteinDistance = new LevenshteinDistance();
return (longerLength - levenshteinDistance.apply(longer, shorter)) / (double) longerLength; */
return (longerLength - editDistance(longer, shorter)) / (double) longerLength;
}
// Example implementation of the Levenshtein Edit Distance
// See http://rosettacode.org/wiki/Levenshtein_distance#Java
public static int editDistance(String s1, String s2) {
s1 = s1.toLowerCase();
s2 = s2.toLowerCase();
int[] costs = new int[s2.length() + 1];
for (int i = 0; i <= s1.length(); i++) {
int lastValue = i;
for (int j = 0; j <= s2.length(); j++) {
if (i == 0)
costs[j] = j;
else {
if (j > 0) {
int newValue = costs[j - 1];
if (s1.charAt(i - 1) != s2.charAt(j - 1))
newValue = Math.min(Math.min(newValue, lastValue),
costs[j]) + 1;
costs[j - 1] = lastValue;
lastValue = newValue;
}
}
}
if (i > 0)
costs[s2.length()] = lastValue;
}
return costs[s2.length()];
}
public static void printSimilarity(String s, String t) {
System.out.println(String.format(
"%.3f is the similarity between \"%s\" and \"%s\"", similarity(s, t), s, t));
}
public static void main(String[] args) {
printSimilarity("", "");
printSimilarity("1234567890", "1");
printSimilarity("1234567890", "123");
printSimilarity("1234567890", "1234567");
printSimilarity("1234567890", "1234567890");
printSimilarity("1234567890", "1234567980");
printSimilarity("47/2010", "472010");
printSimilarity("47/2010", "472011");
printSimilarity("47/2010", "AB.CDEF");
printSimilarity("47/2010", "4B.CDEFG");
printSimilarity("47/2010", "AB.CDEFG");
printSimilarity("The quick fox jumped", "The fox jumped");
printSimilarity("The quick fox jumped", "The fox");
printSimilarity("kitten", "sitting");
}
}
出力:
1.000 is the similarity between "" and ""
0.100 is the similarity between "1234567890" and "1"
0.300 is the similarity between "1234567890" and "123"
0.700 is the similarity between "1234567890" and "1234567"
1.000 is the similarity between "1234567890" and "1234567890"
0.800 is the similarity between "1234567890" and "1234567980"
0.857 is the similarity between "47/2010" and "472010"
0.714 is the similarity between "47/2010" and "472011"
0.000 is the similarity between "47/2010" and "AB.CDEF"
0.125 is the similarity between "47/2010" and "4B.CDEFG"
0.000 is the similarity between "47/2010" and "AB.CDEFG"
0.700 is the similarity between "The quick fox jumped" and "The fox jumped"
0.350 is the similarity between "The quick fox jumped" and "The fox"
0.571 is the similarity between "kitten" and "sitting"