/**
* 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.mahout.math.hadoop.similarity.cooccurrence.measures;
public class TanimotoCoefficientSimilarity extends CountbasedMeasure {
@Override
public double similarity(double dots, double normA, double normB, int numberOfColumns) {
// Return 0 even when dots == 0 since this will cause it to be ignored -- not NaN
return dots / (normA + normB - dots);
}
@Override
public boolean consider(int numNonZeroEntriesA, int numNonZeroEntriesB, double maxValueA, double maxValueB,
double threshold) {
return numNonZeroEntriesA >= numNonZeroEntriesB * threshold &&
numNonZeroEntriesB >= numNonZeroEntriesA * threshold;
}
}