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February 14, 2019 15:55
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Inverse Hamming Distance function for E
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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; | |
/** | |
* The hamming distance between two strings of equal length is the number of | |
* positions at which the corresponding symbols are different. | |
* | |
* <p> | |
* For further explanation about the Hamming Distance, take a look at its | |
* Wikipedia page at http://en.wikipedia.org/wiki/Hamming_distance. | |
* </p> | |
* | |
* @since 1.0 | |
*/ | |
public class HammingDistance implements EditDistance<Integer> { | |
/** | |
* Find the Hamming Distance between two strings with the same | |
* length. | |
* | |
* <p>The distance starts with zero, and for each occurrence of a | |
* different character in either String, it increments the distance | |
* by 1, and finally return its value.</p> | |
* | |
* <p>Since the Hamming Distance can only be calculated between strings of equal length, input of different lengths | |
* will throw IllegalArgumentException</p> | |
* | |
* <pre> | |
* distance.apply("", "") = 0 | |
* distance.apply("pappa", "pappa") = 0 | |
* distance.apply("1011101", "1011111") = 1 | |
* distance.apply("ATCG", "ACCC") = 2 | |
* distance.apply("karolin", "kerstin" = 3 | |
* </pre> | |
* | |
* @param left the first CharSequence, must not be null | |
* @param right the second CharSequence, must not be null | |
* @return distance | |
* @throws IllegalArgumentException if either input is {@code null} or | |
* if they do not have the same length | |
*/ | |
@Override | |
public Integer apply(final CharSequence left, final CharSequence right) { | |
if (left == null || right == null) { | |
throw new IllegalArgumentException("Strings must not be null"); | |
} | |
if (left.length() != right.length()) { | |
throw new IllegalArgumentException("Strings must have the same length"); | |
} | |
int distance = 0; | |
for (int i = 0; i < left.length(); i++) { | |
if (left.charAt(i) != right.charAt(i)) { | |
distance++; | |
} | |
} | |
return distance; | |
} | |
} |
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