PredicatedAverage.java

/*
 * Copyright (c) 2013, SRI International
 * All rights reserved.
 * Licensed under the The BSD 3-Clause License;
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 * 
 * http://opensource.org/licenses/BSD-3-Clause
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 * Neither the name of the aic-util nor the names of its
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 * this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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package com.sri.ai.util.rangeoperation.library.operators;

import com.google.common.annotations.Beta;
import com.google.common.base.Predicate;
import com.sri.ai.util.Util;
import com.sri.ai.util.rangeoperation.core.AbstractAggregateOperator;

/**
 * Similar to {@link Average} but taking a predicate selecting items to be considered in average.
 */
@Beta
public class PredicatedAverage extends AbstractAggregateOperator<Object, Object> {

	protected int weight = 0;
	protected Predicate<Object> predicate;

	public PredicatedAverage(Predicate<Object> predicate) {
		this.predicate = predicate;
	}

	@Override
	public void initialize() {
		result = 0;
		weight = 0;
	}
	
	@Override
	public void increment(Object another) {
		if ( ! predicate.apply(another)) {
			return;
		}

		if (weight == 0) {
			result = another;
			weight = 1;
		}
		else {
			result = Util.incrementalComponentWiseAverageArbitraryDepth(result, weight, another);
			weight++;
		}
	}
}