50 lines
1.9 KiB
Java
50 lines
1.9 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.text.similarity;
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import java.util.Map;
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/**
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* Measures the cosine distance between two character sequences.
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*
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* <p>It utilizes the {@link CosineSimilarity} to compute the distance. Character sequences
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* are converted into vectors through a simple tokenizer that works with a regular expression
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* to split words in a sentence.</p>
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*
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* <p>
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* For further explanation about Cosine Similarity and Cosine Distance, refer to
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* http://en.wikipedia.org/wiki/Cosine_similarity.
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* </p>
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*
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* @since 1.0
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* @see CosineSimilarity
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*/
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public class CosineDistance implements EditDistance<Double> {
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@Override
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public Double apply(final CharSequence left, final CharSequence right) {
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final CharSequence[] leftTokens = RegexTokenizer.INSTANCE.tokenize(left);
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final CharSequence[] rightTokens = RegexTokenizer.INSTANCE.tokenize(right);
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final Map<CharSequence, Integer> leftVector = Counter.of(leftTokens);
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final Map<CharSequence, Integer> rightVector = Counter.of(rightTokens);
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final double similarity = CosineSimilarity.INSTANCE.cosineSimilarity(leftVector, rightVector);
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return 1.0 - similarity;
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}
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}
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