/*
* 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.math3.stat.descriptive.summary;
import java.io.Serializable;
import org.apache.commons.math3.exception.MathIllegalArgumentException;
import org.apache.commons.math3.exception.NullArgumentException;
import org.apache.commons.math3.stat.descriptive.AbstractStorelessUnivariateStatistic;
import org.apache.commons.math3.util.MathUtils;
/**
* Returns the sum of the available values.
* <p>
* If there are no values in the dataset, then 0 is returned.
* If any of the values are
* <code>NaN</code>, then <code>NaN</code> is returned.</p>
* <p>
* <strong>Note that this implementation is not synchronized.</strong> If
* multiple threads access an instance of this class concurrently, and at least
* one of the threads invokes the <code>increment()</code> or
* <code>clear()</code> method, it must be synchronized externally.</p>
*
*/
public class Sum extends AbstractStorelessUnivariateStatistic implements Serializable {
/** Serializable version identifier */
private static final long serialVersionUID = -8231831954703408316L;
/** */
private long n;
/**
* The currently running sum.
*/
private double value;
/**
* Create a Sum instance
*/
public Sum() {
n = 0;
value = 0;
}
/**
* Copy constructor, creates a new {@code Sum} identical
* to the {@code original}
*
* @param original the {@code Sum} instance to copy
* @throws NullArgumentException if original is null
*/
public Sum(Sum original) throws NullArgumentException {
copy(original, this);
}
/**
* {@inheritDoc}
*/
@Override
public void increment(final double d) {
value += d;
n++;
}
/**
* {@inheritDoc}
*/
@Override
public double getResult() {
return value;
}
/**
* {@inheritDoc}
*/
public long getN() {
return n;
}
/**
* {@inheritDoc}
*/
@Override
public void clear() {
value = 0;
n = 0;
}
/**
* The sum of the entries in the specified portion of
* the input array, or 0 if the designated subarray
* is empty.
* <p>
* Throws <code>MathIllegalArgumentException</code> if the array is null.</p>
*
* @param values the input array
* @param begin index of the first array element to include
* @param length the number of elements to include
* @return the sum of the values or 0 if length = 0
* @throws MathIllegalArgumentException if the array is null or the array index
* parameters are not valid
*/
@Override
public double evaluate(final double[] values, final int begin, final int length)
throws MathIllegalArgumentException {
double sum = Double.NaN;
if (test(values, begin, length, true)) {
sum = 0.0;
for (int i = begin; i < begin + length; i++) {
sum += values[i];
}
}
return sum;
}
/**
* The weighted sum of the entries in the specified portion of
* the input array, or 0 if the designated subarray
* is empty.
* <p>
* Throws <code>MathIllegalArgumentException</code> if any of the following are true:
* <ul><li>the values array is null</li>
* <li>the weights array is null</li>
* <li>the weights array does not have the same length as the values array</li>
* <li>the weights array contains one or more infinite values</li>
* <li>the weights array contains one or more NaN values</li>
* <li>the weights array contains negative values</li>
* <li>the start and length arguments do not determine a valid array</li>
* </ul></p>
* <p>
* Uses the formula, <pre>
* weighted sum = Σ(values[i] * weights[i])
* </pre></p>
*
* @param values the input array
* @param weights the weights array
* @param begin index of the first array element to include
* @param length the number of elements to include
* @return the sum of the values or 0 if length = 0
* @throws MathIllegalArgumentException if the parameters are not valid
* @since 2.1
*/
public double evaluate(final double[] values, final double[] weights,
final int begin, final int length) throws MathIllegalArgumentException {
double sum = Double.NaN;
if (test(values, weights, begin, length, true)) {
sum = 0.0;
for (int i = begin; i < begin + length; i++) {
sum += values[i] * weights[i];
}
}
return sum;
}
/**
* The weighted sum of the entries in the the input array.
* <p>
* Throws <code>MathIllegalArgumentException</code> if any of the following are true:
* <ul><li>the values array is null</li>
* <li>the weights array is null</li>
* <li>the weights array does not have the same length as the values array</li>
* <li>the weights array contains one or more infinite values</li>
* <li>the weights array contains one or more NaN values</li>
* <li>the weights array contains negative values</li>
* </ul></p>
* <p>
* Uses the formula, <pre>
* weighted sum = Σ(values[i] * weights[i])
* </pre></p>
*
* @param values the input array
* @param weights the weights array
* @return the sum of the values or Double.NaN if length = 0
* @throws MathIllegalArgumentException if the parameters are not valid
* @since 2.1
*/
public double evaluate(final double[] values, final double[] weights)
throws MathIllegalArgumentException {
return evaluate(values, weights, 0, values.length);
}
/**
* {@inheritDoc}
*/
@Override
public Sum copy() {
Sum result = new Sum();
// No try-catch or advertised exception because args are valid
copy(this, result);
return result;
}
/**
* Copies source to dest.
* <p>Neither source nor dest can be null.</p>
*
* @param source Sum to copy
* @param dest Sum to copy to
* @throws NullArgumentException if either source or dest is null
*/
public static void copy(Sum source, Sum dest)
throws NullArgumentException {
MathUtils.checkNotNull(source);
MathUtils.checkNotNull(dest);
dest.setData(source.getDataRef());
dest.n = source.n;
dest.value = source.value;
}
}