All Downloads are FREE. Search and download functionalities are using the official Maven repository.

com.groupbyinc.common.apache.commons.text.similarity.JaccardSimilarity Maven / Gradle / Ivy

There is a newer version: 198
Show newest version
/*
 * 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;

import java.util.HashSet;
import java.util.Set;

/**
 * Measures the Jaccard similarity (aka Jaccard index) of two sets of character
 * sequence. Jaccard similarity is the size of the intersection divided by the
 * size of the union of the two sets.
 *
 * 

* For further explanation about Jaccard Similarity, refer * https://en.wikipedia.org/wiki/Jaccard_index *

* * @since 1.0 */ public class JaccardSimilarity implements SimilarityScore { /** * Calculates Jaccard Similarity of two set character sequence passed as * input. * * @param left first character sequence * @param right second character sequence * @return index * @throws IllegalArgumentException * if either String input {@code null} */ @Override public Double apply(final CharSequence left, final CharSequence right) { if (left == null || right == null) { throw new IllegalArgumentException("Input cannot be null"); } return Math.round(calculateJaccardSimilarity(left, right) * 100d) / 100d; } /** * Calculates Jaccard Similarity of two character sequences passed as * input. Does the calculation by identifying the union (characters in at * least one of the two sets) of the two sets and intersection (characters * which are present in set one which are present in set two) * * @param left first character sequence * @param right second character sequence * @return index */ private Double calculateJaccardSimilarity(final CharSequence left, final CharSequence right) { final Set intersectionSet = new HashSet<>(); final Set unionSet = new HashSet<>(); boolean unionFilled = false; final int leftLength = left.length(); final int rightLength = right.length(); if (leftLength == 0 || rightLength == 0) { return 0d; } for (int leftIndex = 0; leftIndex < leftLength; leftIndex++) { unionSet.add(String.valueOf(left.charAt(leftIndex))); for (int rightIndex = 0; rightIndex < rightLength; rightIndex++) { if (!unionFilled) { unionSet.add(String.valueOf(right.charAt(rightIndex))); } if (left.charAt(leftIndex) == right.charAt(rightIndex)) { intersectionSet.add(String.valueOf(left.charAt(leftIndex))); } } unionFilled = true; } return Double.valueOf(intersectionSet.size()) / Double.valueOf(unionSet.size()); } }




© 2015 - 2024 Weber Informatics LLC | Privacy Policy