/*
* 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.math4.stat.descriptive;
import org.apache.commons.math4.exception.MathIllegalArgumentException;
import org.apache.commons.math4.exception.NullArgumentException;
import org.apache.commons.math4.exception.util.LocalizedFormats;
import org.apache.commons.math4.util.MathArrays;
import org.apache.commons.math4.util.MathUtils;
import org.apache.commons.numbers.core.Precision;
/**
* Abstract base class for implementations of the
* {@link StorelessUnivariateStatistic} interface.
* <p>
* Provides default {@code evaluate(double[],...)} and {@code incrementAll(double[])}
* implementations.
* <p>
* <strong>Note that these implementations are not synchronized.</strong>
*/
public abstract class AbstractStorelessUnivariateStatistic
implements StorelessUnivariateStatistic {
/**
* This default implementation creates a copy of this {@link StorelessUnivariateStatistic}
* instance, calls {@link #clear} on it, then calls {@link #incrementAll} with the specified
* portion of the input array, and then uses {@link #getResult} to compute the return value.
* <p>
* Note that this implementation does not change the internal state of the statistic.
* <p>
* Implementations may override this method with a more efficient and possibly more
* accurate implementation that works directly with the input array.
* <p>
* If the array is null, a MathIllegalArgumentException is thrown.
*
* @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.math4.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 creates a copy of this {@link StorelessUnivariateStatistic}
* instance, calls {@link #clear} on it, then calls {@link #incrementAll} with the specified
* portion of the input array, and then uses {@link #getResult} to compute the return value.
* <p>
* Note that this implementation does not change the internal state of the statistic.
* <p>
* Implementations may override this method with a more efficient and possibly more
* accurate implementation that works directly with the input array.
* <p>
* If the array is null or the index parameters are not valid, an
* MathIllegalArgumentException is thrown.
*
* @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.math4.stat.descriptive.UnivariateStatistic#evaluate(double[], int, int)
*/
@Override
public double evaluate(final double[] values, final int begin, final int length)
throws MathIllegalArgumentException {
if (MathArrays.verifyValues(values, begin, length)) {
final StorelessUnivariateStatistic stat = copy();
stat.clear();
stat.incrementAll(values, begin, length);
return stat.getResult();
}
return Double.NaN;
}
/**
* {@inheritDoc}
*/
@Override
public abstract StorelessUnivariateStatistic copy();
/**
* {@inheritDoc}
*/
@Override
public abstract void clear();
/**
* {@inheritDoc}
*/
@Override
public abstract double getResult();
/**
* {@inheritDoc}
*/
@Override
public abstract void increment(final double d);
/**
* This default implementation just calls {@link #increment} in a loop over
* the input array.
* <p>
* Throws IllegalArgumentException if the input values array is null.
*
* @param values values to add
* @throws MathIllegalArgumentException if values is null
* @see StorelessUnivariateStatistic#incrementAll(double[])
*/
@Override
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 {@link #increment} in a loop over
* the specified portion of the input array.
* <p>
* Throws IllegalArgumentException if the input values array is null.
*
* @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 StorelessUnivariateStatistic#incrementAll(double[], int, int)
*/
@Override
public void incrementAll(double[] values, int begin, int length) throws MathIllegalArgumentException {
if (MathArrays.verifyValues(values, begin, length)) {
int k = begin + length;
for (int i = begin; i < k; i++) {
increment(values[i]);
}
}
}
/**
* Returns true iff <code>object</code> is the same type of
* {@link StorelessUnivariateStatistic} (the object's class equals this
* instance) 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 == null || object.getClass() != this.getClass()) {
return false;
}
StorelessUnivariateStatistic stat = (StorelessUnivariateStatistic) object;
return Precision.equalsIncludingNaN(stat.getResult(), this.getResult()) &&
Precision.equalsIncludingNaN(stat.getN(), this.getN());
}
/**
* Returns hash code based on getResult() and getN().
*
* @return hash code
*/
@Override
public int hashCode() {
return 31 * (31 + MathUtils.hash(getResult())) + MathUtils.hash(getN());
}
}