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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
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 *
 *      http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.commons.math3.stat.descriptive;

import org.apache.commons.math3.exception.util.LocalizedFormats;
import org.apache.commons.math3.exception.MathIllegalArgumentException;
import org.apache.commons.math3.exception.NullArgumentException;
import org.apache.commons.math3.util.MathUtils;
import org.apache.commons.math3.util.Precision;

Abstract implementation of the StorelessUnivariateStatistic interface. 

Provides default evaluate() and incrementAll(double[])
implementations.

Note that these implementations are not synchronized.
/**
 *
 * Abstract implementation of the {@link StorelessUnivariateStatistic} interface.
 * <p>
 * Provides default <code>evaluate()</code> and <code>incrementAll(double[])</code>
 * implementations.</p>
 * <p>
 * <strong>Note that these implementations are not synchronized.</strong></p>
 *
 */
public abstract class AbstractStorelessUnivariateStatistic
    extends AbstractUnivariateStatistic
    implements StorelessUnivariateStatistic {

    
This default implementation calls clear, then invokes increment in a loop over the the input array, and then uses getResult to compute the return value. 
 Note that this implementation changes the internal state of the statistic. Its side effects are the same as invoking clear and then incrementAll(double[]).

Implementations may override this method with a more efficient and
possibly more accurate implementation that works directly with the
input array.

If the array is null, a MathIllegalArgumentException is thrown.
Params:
values – input array
Throws:
MathIllegalArgumentException – if values is null
See Also:
UnivariateStatistic.evaluate(double[])
Returns:
the value of the statistic applied to the input array/**
     * This default implementation calls {@link #clear}, then invokes
     * {@link #increment} in a loop over the the input array, and then uses
     * {@link #getResult} to compute the return value.
     * <p>
     * Note that this implementation changes the internal state of the
     * statistic.  Its side effects are the same as invoking {@link #clear} and
     * then {@link #incrementAll(double[])}.</p>
     * <p>
     * Implementations may override this method with a more efficient and
     * possibly more accurate implementation that works directly with the
     * input array.</p>
     * <p>
     * If the array is null, a MathIllegalArgumentException is thrown.</p>
     * @param values input array
     * @return the value of the statistic applied to the input array
     * @throws MathIllegalArgumentException if values is null
     * @see org.apache.commons.math3.stat.descriptive.UnivariateStatistic#evaluate(double[])
     */
    @Override
    public double evaluate(final double[] values) throws MathIllegalArgumentException {
        if (values == null) {
            throw new NullArgumentException(LocalizedFormats.INPUT_ARRAY);
        }
        return evaluate(values, 0, values.length);
    }

    
This default implementation calls clear, then invokes increment in a loop over the specified portion of the input array, and then uses getResult to compute the return value. 
 Note that this implementation changes the internal state of the statistic. Its side effects are the same as invoking clear and then incrementAll(double[], int, int).

Implementations may override this method with a more efficient and
possibly more accurate implementation that works directly with the
input array.

If the array is null or the index parameters are not valid, an
MathIllegalArgumentException is thrown.
Params:
values – the input array
begin – the index of the first element to include
length – the number of elements to include
Throws:
MathIllegalArgumentException – if the array is null or the indices are not valid
See Also:
UnivariateStatistic.evaluate(double[], int, int)
Returns:
the value of the statistic applied to the included array entries/**
     * This default implementation calls {@link #clear}, then invokes
     * {@link #increment} in a loop over the specified portion of the input
     * array, and then uses {@link #getResult} to compute the return value.
     * <p>
     * Note that this implementation changes the internal state of the
     * statistic.  Its side effects are the same as invoking {@link #clear} and
     * then {@link #incrementAll(double[], int, int)}.</p>
     * <p>
     * Implementations may override this method with a more efficient and
     * possibly more accurate implementation that works directly with the
     * input array.</p>
     * <p>
     * If the array is null or the index parameters are not valid, an
     * MathIllegalArgumentException is thrown.</p>
     * @param values the input array
     * @param begin the index of the first element to include
     * @param length the number of elements to include
     * @return the value of the statistic applied to the included array entries
     * @throws MathIllegalArgumentException if the array is null or the indices are not valid
     * @see org.apache.commons.math3.stat.descriptive.UnivariateStatistic#evaluate(double[], int, int)
     */
    @Override
    public double evaluate(final double[] values, final int begin,
            final int length) throws MathIllegalArgumentException {
        if (test(values, begin, length)) {
            clear();
            incrementAll(values, begin, length);
        }
        return getResult();
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public abstract StorelessUnivariateStatistic copy();

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    public abstract void clear();

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    public abstract double getResult();

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    public abstract void increment(final double d);

    
This default implementation just calls increment in a loop over the input array. 

Throws IllegalArgumentException if the input values array is null.
Params:
values – values to add
Throws:
MathIllegalArgumentException – if values is null
See Also:
StorelessUnivariateStatistic.incrementAll(double[])/**
     * This default implementation just calls {@link #increment} in a loop over
     * the input array.
     * <p>
     * Throws IllegalArgumentException if the input values array is null.</p>
     *
     * @param values values to add
     * @throws MathIllegalArgumentException if values is null
     * @see org.apache.commons.math3.stat.descriptive.StorelessUnivariateStatistic#incrementAll(double[])
     */
    public void incrementAll(double[] values) throws MathIllegalArgumentException {
        if (values == null) {
            throw new NullArgumentException(LocalizedFormats.INPUT_ARRAY);
        }
        incrementAll(values, 0, values.length);
    }

    
This default implementation just calls increment in a loop over the specified portion of the input array. 

Throws IllegalArgumentException if the input values array is null.
Params:
values –  array holding values to add
begin –   index of the first array element to add
length –  number of array elements to add
Throws:
MathIllegalArgumentException – if values is null
See Also:
StorelessUnivariateStatistic.incrementAll(double[], int, int)/**
     * This default implementation just calls {@link #increment} in a loop over
     * the specified portion of the input array.
     * <p>
     * Throws IllegalArgumentException if the input values array is null.</p>
     *
     * @param values  array holding values to add
     * @param begin   index of the first array element to add
     * @param length  number of array elements to add
     * @throws MathIllegalArgumentException if values is null
     * @see org.apache.commons.math3.stat.descriptive.StorelessUnivariateStatistic#incrementAll(double[], int, int)
     */
    public void incrementAll(double[] values, int begin, int length) throws MathIllegalArgumentException {
        if (test(values, begin, length)) {
            int k = begin + length;
            for (int i = begin; i < k; i++) {
                increment(values[i]);
            }
        }
    }

    
Returns true iff object is an
AbstractStorelessUnivariateStatistic returning the same
values as this for getResult() and getN()
Params:
object – object to test equality against.
Returns:
true if object returns the same value as this/**
     * Returns true iff <code>object</code> is an
     * <code>AbstractStorelessUnivariateStatistic</code> returning the same
     * values as this for <code>getResult()</code> and <code>getN()</code>
     * @param object object to test equality against.
     * @return true if object returns the same value as this
     */
    @Override
    public boolean equals(Object object) {
        if (object == this ) {
            return true;
        }
       if (object instanceof AbstractStorelessUnivariateStatistic == false) {
            return false;
        }
        AbstractStorelessUnivariateStatistic stat = (AbstractStorelessUnivariateStatistic) object;
        return Precision.equalsIncludingNaN(stat.getResult(), this.getResult()) &&
               Precision.equalsIncludingNaN(stat.getN(), this.getN());
    }

    
Returns hash code based on getResult() and getN()
Returns:
hash code/**
     * Returns hash code based on getResult() and getN()
     *
     * @return hash code
     */
    @Override
    public int hashCode() {
        return 31* (31 + MathUtils.hash(getResult())) + MathUtils.hash(getN());
    }

}