Java tutorial
/* * 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.math.stat.descriptive; import org.apache.commons.math.MathRuntimeException; import org.apache.commons.math.exception.DimensionMismatchException; import org.apache.commons.math.exception.NotPositiveException; import org.apache.commons.math.exception.NullArgumentException; import org.apache.commons.math.exception.util.LocalizedFormats; /** * Abstract base class for all implementations of the * {@link UnivariateStatistic} interface. * <p> * Provides a default implementation of <code>evaluate(double[]),</code> * delegating to <code>evaluate(double[], int, int)</code> in the natural way. * </p> * <p> * Also includes a <code>test</code> method that performs generic parameter * validation for the <code>evaluate</code> methods.</p> * * @version $Revision: 1006299 $ $Date: 2010-10-10 16:47:17 +0200 (dim. 10 oct. 2010) $ */ public abstract class AbstractUnivariateStatistic implements UnivariateStatistic { /** Stored data. */ private double[] storedData; /** * Set the data array. * <p> * The stored value is a copy of the parameter array, not the array itself * </p> * @param values data array to store (may be null to remove stored data) * @see #evaluate() */ public void setData(final double[] values) { storedData = (values == null) ? null : values.clone(); } /** * Get a copy of the stored data array. * @return copy of the stored data array (may be null) */ public double[] getData() { return (storedData == null) ? null : storedData.clone(); } /** * Get a reference to the stored data array. * @return reference to the stored data array (may be null) */ protected double[] getDataRef() { return storedData; } /** * Set the data array. * @param values data array to store * @param begin the index of the first element to include * @param length the number of elements to include * @see #evaluate() */ public void setData(final double[] values, final int begin, final int length) { storedData = new double[length]; System.arraycopy(values, begin, storedData, 0, length); } /** * Returns the result of evaluating the statistic over the stored data. * <p> * The stored array is the one which was set by previous calls to * </p> * @return the value of the statistic applied to the stored data */ public double evaluate() { return evaluate(storedData); } /** * {@inheritDoc} */ public double evaluate(final double[] values) { test(values, 0, 0); return evaluate(values, 0, values.length); } /** * {@inheritDoc} */ public abstract double evaluate(final double[] values, final int begin, final int length); /** * {@inheritDoc} */ public abstract UnivariateStatistic copy(); /** * This method is used by <code>evaluate(double[], int, int)</code> methods * to verify that the input parameters designate a subarray of positive length. * <p> * <ul> * <li>returns <code>true</code> iff the parameters designate a subarray of * positive length</li> * <li>throws <code>IllegalArgumentException</code> if the array is null or * or the indices are invalid</li> * <li>returns <code>false</li> if the array is non-null, but * <code>length</code> is 0. * </ul></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 true if the parameters are valid and designate a subarray of positive length * @throws IllegalArgumentException if the indices are invalid or the array is null */ protected boolean test(final double[] values, final int begin, final int length) { if (values == null) { throw new NullArgumentException(LocalizedFormats.INPUT_ARRAY); } if (begin < 0) { throw new NotPositiveException(LocalizedFormats.START_POSITION, begin); } if (length < 0) { throw new NotPositiveException(LocalizedFormats.LENGTH, length); } if (begin + length > values.length) { throw MathRuntimeException .createIllegalArgumentException(LocalizedFormats.SUBARRAY_ENDS_AFTER_ARRAY_END); } if (length == 0) { return false; } return true; } /** * This method is used by <code>evaluate(double[], double[], int, int)</code> methods * to verify that the begin and length parameters designate a subarray of positive length * and the weights are all non-negative, non-NaN, finite, and not all zero. * <p> * <ul> * <li>returns <code>true</code> iff the parameters designate a subarray of * positive length and the weights array contains legitimate values.</li> * <li>throws <code>IllegalArgumentException</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> * </li> * <li>returns <code>false</li> if the array is non-null, but * <code>length</code> is 0. * </ul></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 true if the parameters are valid and designate a subarray of positive length * @throws IllegalArgumentException if the indices are invalid or the array is null * @since 2.1 */ protected boolean test(final double[] values, final double[] weights, final int begin, final int length) { if (weights == null) { throw new NullArgumentException(LocalizedFormats.INPUT_ARRAY); } if (weights.length != values.length) { throw new DimensionMismatchException(weights.length, values.length); } boolean containsPositiveWeight = false; for (int i = begin; i < begin + length; i++) { if (Double.isNaN(weights[i])) { throw MathRuntimeException.createIllegalArgumentException(LocalizedFormats.NAN_ELEMENT_AT_INDEX, i); } if (Double.isInfinite(weights[i])) { throw MathRuntimeException.createIllegalArgumentException(LocalizedFormats.INFINITE_ARRAY_ELEMENT, weights[i], i); } if (weights[i] < 0) { throw MathRuntimeException .createIllegalArgumentException(LocalizedFormats.NEGATIVE_ELEMENT_AT_INDEX, i, weights[i]); } if (!containsPositiveWeight && weights[i] > 0.0) { containsPositiveWeight = true; } } if (!containsPositiveWeight) { throw MathRuntimeException .createIllegalArgumentException(LocalizedFormats.WEIGHT_AT_LEAST_ONE_NON_ZERO); } return test(values, begin, length); } }