SetOperations.java
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* 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,
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* See the License for the specific language governing permissions and
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*/
package org.apache.commons.collections4.bloomfilter;
import java.util.function.LongBinaryOperator;
/**
* Implementations of set operations on BitMapProducers.
*
* @since 4.5
*/
public final class SetOperations {
/**
* Calculates the cardinality of the logical {@code AND} of the bit maps for the two filters.
* @param first the first BitMapProducer.
* @param second the second BitMapProducer
* @return the cardinality of the {@code AND} of the filters.
*/
public static int andCardinality(final BitMapProducer first, final BitMapProducer second) {
return cardinality(first, second, (x, y) -> x & y);
}
/**
* Calculates the cardinality of a BitMapProducer. By necessity this method will visit each bit map
* created by the producer.
* @param producer the Producer to calculate the cardinality for.
* @return the cardinality of the bit maps produced by the producer.
*/
public static int cardinality(final BitMapProducer producer) {
final int[] cardinality = new int[1];
producer.forEachBitMap(l -> {
cardinality[0] += Long.bitCount(l);
return true;
});
return cardinality[0];
}
/**
* Calculates the cardinality of the result of a LongBinaryOperator using the
* {@code BitMapProducer.makePredicate} method.
* @param first the first BitMapProducer
* @param second the second BitMapProducer
* @param op a long binary operation on where x = {@code first} and y = {@code second} bitmap producers.
* @return the calculated cardinality.
*/
private static int cardinality(final BitMapProducer first, final BitMapProducer second, final LongBinaryOperator op) {
final int[] cardinality = new int[1];
first.forEachBitMapPair(second, (x, y) -> {
cardinality[0] += Long.bitCount(op.applyAsLong(x, y));
return true;
});
return cardinality[0];
}
/**
* Calculates the Cosine distance between two BitMapProducer.
*
* <p>Cosine distance is defined as {@code 1 - Cosine similarity}</p>
*
* @param first the first BitMapProducer.
* @param second the second BitMapProducer.
* @return the jaccard distance.
*/
public static double cosineDistance(final BitMapProducer first, final BitMapProducer second) {
return 1.0 - cosineSimilarity(first, second);
}
/**
* Calculates the Cosine similarity between two BitMapProducers.
* <p> Also known as Orchini similarity and the Tucker coefficient of congruence or
* Ochiai similarity.</p>
*
* <p>If either producer is empty the result is 0 (zero)</p>
*
* @param first the first BitMapProducer.
* @param second the second BitMapProducer.
* @return the Cosine similarity.
*/
public static double cosineSimilarity(final BitMapProducer first, final BitMapProducer second) {
final int numerator = andCardinality(first, second);
// Given that the cardinality is an int then the product as a double will not
// overflow, we can use one sqrt:
return numerator == 0 ? 0 : numerator / Math.sqrt(cardinality(first) * cardinality(second));
}
/**
* Calculates the Cosine similarity between two Bloom filters.
* <p> Also known as Orchini similarity and the Tucker coefficient of congruence or
* Ochiai similarity.</p>
*
* <p>If either filter is empty (no enabled bits) the result is 0 (zero)</p>
*
* <p>This is a version of cosineSimilarity optimized for Bloom filters.</p>
*
* @param first the first Bloom filter.
* @param second the second Bloom filter.
* @return the Cosine similarity.
*/
public static double cosineSimilarity(final BloomFilter first, final BloomFilter second) {
final int numerator = andCardinality(first, second);
// Given that the cardinality is an int then the product as a double will not
// overflow, we can use one sqrt:
return numerator == 0 ? 0 : numerator / Math.sqrt(first.cardinality() * second.cardinality());
}
/**
* Calculates the Hamming distance between two BitMapProducers.
*
* @param first the first BitMapProducer.
* @param second the second BitMapProducer.
* @return the Hamming distance.
*/
public static int hammingDistance(final BitMapProducer first, final BitMapProducer second) {
return xorCardinality(first, second);
}
/**
* Calculates the Jaccard distance between two BitMapProducer.
*
* <p>Jaccard distance is defined as {@code 1 - Jaccard similarity}</p>
*
* @param first the first BitMapProducer.
* @param second the second BitMapProducer.
* @return the Jaccard distance.
*/
public static double jaccardDistance(final BitMapProducer first, final BitMapProducer second) {
return 1.0 - jaccardSimilarity(first, second);
}
/**
* Calculates the Jaccard similarity between two BitMapProducer.
*
* <p>Also known as Jaccard index, Intersection over Union, and Jaccard similarity coefficient</p>
*
* @param first the first BitMapProducer.
* @param second the second BitMapProducer.
* @return the Jaccard similarity.
*/
public static double jaccardSimilarity(final BitMapProducer first, final BitMapProducer second) {
final int[] cardinality = new int[2];
first.forEachBitMapPair(second, (x, y) -> {
cardinality[0] += Long.bitCount(x & y);
cardinality[1] += Long.bitCount(x | y);
return true;
});
final int intersection = cardinality[0];
return intersection == 0 ? 0 : intersection / (double) cardinality[1];
}
/**
* Calculates the cardinality of the logical {@code OR} of the bit maps for the two filters.
* @param first the first BitMapProducer.
* @param second the second BitMapProducer
* @return the cardinality of the {@code OR} of the filters.
*/
public static int orCardinality(final BitMapProducer first, final BitMapProducer second) {
return cardinality(first, second, (x, y) -> x | y);
}
/**
* Calculates the cardinality of the logical {@code XOR} of the bit maps for the two filters.
* @param first the first BitMapProducer.
* @param second the second BitMapProducer
* @return the cardinality of the {@code XOR} of the filters.
*/
public static int xorCardinality(final BitMapProducer first, final BitMapProducer second) {
return cardinality(first, second, (x, y) -> x ^ y);
}
/**
* Do not instantiate.
*/
private SetOperations() {
}
}