| /* |
| * 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.Map; |
| |
| import org.apache.commons.text.similarity.internal.Counter; |
| import org.apache.commons.text.similarity.internal.RegexTokenizer; |
| import org.apache.commons.text.similarity.internal.Tokenizer; |
| |
| /** |
| * Measures the cosine distance between two character sequences. |
| * |
| * <p>It utilizes the CosineSimilarity to compute the distance. Character sequences |
| * are converted into vectors through a simple tokenizer that works with </p> |
| * |
| * @since 0.1 |
| */ |
| public class CosineDistance implements StringMetric<Double> { |
| /** |
| * Tokenizer used to convert the character sequence into a vector. |
| */ |
| private final Tokenizer<CharSequence> tokenizer = new RegexTokenizer(); |
| /** |
| * Cosine similarity. |
| */ |
| private final CosineSimilarity cosineSimilarity = new CosineSimilarity(); |
| |
| @Override |
| public Double apply(CharSequence left, CharSequence right) { |
| CharSequence[] leftTokens = tokenizer.tokenize(left); |
| CharSequence[] rightTokens = tokenizer.tokenize(right); |
| |
| Map<CharSequence, Integer> leftVector = Counter.of(leftTokens); |
| Map<CharSequence, Integer> rightVector = Counter.of(rightTokens); |
| double similarity = cosineSimilarity.cosineSimilarity(leftVector, rightVector); |
| return 1.0 - similarity; |
| } |
| |
| } |