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Apache Commons Text is a library focused on algorithms working on strings.
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.text.similarity;
/**
* An edit distance algorithm based on the length of the longest common subsequence between two strings.
*
*
* This code is directly based upon the implementation in {@link LongestCommonSubsequence}.
*
*
*
* For reference see:
* https://en.wikipedia.org/wiki/Longest_common_subsequence_problem.
*
*
* For further reading see:
*
* Lothaire, M. Applied combinatorics on words. New York: Cambridge U Press, 2005. 12-13
*
* @since 1.0
*/
public class LongestCommonSubsequenceDistance implements EditDistance {
/**
* Calculates an edit distance between two {@code CharSequence}'s {@code left} and
* {@code right} as: {@code left.length() + right.length() - 2 * LCS(left, right)}, where
* {@code LCS} is given in {@link LongestCommonSubsequence#apply(CharSequence, CharSequence)}.
*
* @param left first character sequence
* @param right second character sequence
* @return distance
* @throws IllegalArgumentException
* if either String input {@code null}
*/
@Override
public Integer apply(final CharSequence left, final CharSequence right) {
// Quick return for invalid inputs
if (left == null || right == null) {
throw new IllegalArgumentException("Inputs must not be null");
}
return left.length() + right.length() - 2 * LongestCommonSubsequence.INSTANCE.apply(left, right);
}
}
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