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A Java's Collaborative Filtering library to carry out experiments in research of Collaborative Filtering based Recommender Systems. The library has been designed from researchers to researchers.
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/*
* 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.util;
import java.io.Serializable;
import java.util.Arrays;
import org.apache.commons.math3.exception.MathIllegalArgumentException;
import org.apache.commons.math3.exception.MathIllegalStateException;
import org.apache.commons.math3.exception.MathInternalError;
import org.apache.commons.math3.exception.NullArgumentException;
import org.apache.commons.math3.exception.NotStrictlyPositiveException;
import org.apache.commons.math3.exception.NumberIsTooSmallException;
import org.apache.commons.math3.exception.util.LocalizedFormats;
/**
*
* A variable length {@link DoubleArray} implementation that automatically
* handles expanding and contracting its internal storage array as elements
* are added and removed.
*
* Important note: Usage should not assume that this class is thread-safe
* even though some of the methods are {@code synchronized}.
* This qualifier will be dropped in the next major release (4.0).
*
* The internal storage array starts with capacity determined by the
* {@code initialCapacity} property, which can be set by the constructor.
* The default initial capacity is 16. Adding elements using
* {@link #addElement(double)} appends elements to the end of the array.
* When there are no open entries at the end of the internal storage array,
* the array is expanded. The size of the expanded array depends on the
* {@code expansionMode} and {@code expansionFactor} properties.
* The {@code expansionMode} determines whether the size of the array is
* multiplied by the {@code expansionFactor}
* ({@link ExpansionMode#MULTIPLICATIVE}) or if the expansion is additive
* ({@link ExpansionMode#ADDITIVE} -- {@code expansionFactor} storage
* locations added).
* The default {@code expansionMode} is {@code MULTIPLICATIVE} and the default
* {@code expansionFactor} is 2.
*
*
* The {@link #addElementRolling(double)} method adds a new element to the end
* of the internal storage array and adjusts the "usable window" of the
* internal array forward by one position (effectively making what was the
* second element the first, and so on). Repeated activations of this method
* (or activation of {@link #discardFrontElements(int)}) will effectively orphan
* the storage locations at the beginning of the internal storage array. To
* reclaim this storage, each time one of these methods is activated, the size
* of the internal storage array is compared to the number of addressable
* elements (the {@code numElements} property) and if the difference
* is too large, the internal array is contracted to size
* {@code numElements + 1}. The determination of when the internal
* storage array is "too large" depends on the {@code expansionMode} and
* {@code contractionFactor} properties. If the {@code expansionMode}
* is {@code MULTIPLICATIVE}, contraction is triggered when the
* ratio between storage array length and {@code numElements} exceeds
* {@code contractionFactor.} If the {@code expansionMode}
* is {@code ADDITIVE}, the number of excess storage locations
* is compared to {@code contractionFactor}.
*
*
* To avoid cycles of expansions and contractions, the
* {@code expansionFactor} must not exceed the {@code contractionFactor}.
* Constructors and mutators for both of these properties enforce this
* requirement, throwing a {@code MathIllegalArgumentException} if it is
* violated.
*
*/
public class ResizableDoubleArray implements DoubleArray, Serializable {
/** Additive expansion mode.
* @deprecated As of 3.1. Please use {@link ExpansionMode#ADDITIVE} instead.
*/
@Deprecated
public static final int ADDITIVE_MODE = 1;
/** Multiplicative expansion mode.
* @deprecated As of 3.1. Please use {@link ExpansionMode#MULTIPLICATIVE} instead.
*/
@Deprecated
public static final int MULTIPLICATIVE_MODE = 0;
/** Serializable version identifier. */
private static final long serialVersionUID = -3485529955529426875L;
/** Default value for initial capacity. */
private static final int DEFAULT_INITIAL_CAPACITY = 16;
/** Default value for array size modifier. */
private static final double DEFAULT_EXPANSION_FACTOR = 2.0;
/**
* Default value for the difference between {@link #contractionCriterion}
* and {@link #expansionFactor}.
*/
private static final double DEFAULT_CONTRACTION_DELTA = 0.5;
/**
* The contraction criteria determines when the internal array will be
* contracted to fit the number of elements contained in the element
* array + 1.
*/
private double contractionCriterion = 2.5;
/**
* The expansion factor of the array. When the array needs to be expanded,
* the new array size will be
* {@code internalArray.length * expansionFactor}
* if {@code expansionMode} is set to MULTIPLICATIVE_MODE, or
* {@code internalArray.length + expansionFactor} if
* {@code expansionMode} is set to ADDITIVE_MODE.
*/
private double expansionFactor = 2.0;
/**
* Determines whether array expansion by {@code expansionFactor}
* is additive or multiplicative.
*/
private ExpansionMode expansionMode = ExpansionMode.MULTIPLICATIVE;
/**
* The internal storage array.
*/
private double[] internalArray;
/**
* The number of addressable elements in the array. Note that this
* has nothing to do with the length of the internal storage array.
*/
private int numElements = 0;
/**
* The position of the first addressable element in the internal storage
* array. The addressable elements in the array are
* {@code internalArray[startIndex],...,internalArray[startIndex + numElements - 1]}.
*/
private int startIndex = 0;
/**
* Specification of expansion algorithm.
* @since 3.1
*/
public enum ExpansionMode {
/** Multiplicative expansion mode. */
MULTIPLICATIVE,
/** Additive expansion mode. */
ADDITIVE
}
/**
* Creates an instance with default properties.
*
* - {@code initialCapacity = 16}
* - {@code expansionMode = MULTIPLICATIVE}
* - {@code expansionFactor = 2.0}
* - {@code contractionCriterion = 2.5}
*
*/
public ResizableDoubleArray() {
this(DEFAULT_INITIAL_CAPACITY);
}
/**
* Creates an instance with the specified initial capacity.
* Other properties take default values:
*
* - {@code expansionMode = MULTIPLICATIVE}
* - {@code expansionFactor = 2.0}
* - {@code contractionCriterion = 2.5}
*
* @param initialCapacity Initial size of the internal storage array.
* @throws MathIllegalArgumentException if {@code initialCapacity <= 0}.
*/
public ResizableDoubleArray(int initialCapacity)
throws MathIllegalArgumentException {
this(initialCapacity, DEFAULT_EXPANSION_FACTOR);
}
/**
* Creates an instance from an existing {@code double[]} with the
* initial capacity and numElements corresponding to the size of
* the supplied {@code double[]} array.
* If the supplied array is null, a new empty array with the default
* initial capacity will be created.
* The input array is copied, not referenced.
* Other properties take default values:
*
* - {@code initialCapacity = 16}
* - {@code expansionMode = MULTIPLICATIVE}
* - {@code expansionFactor = 2.0}
* - {@code contractionCriterion = 2.5}
*
*
* @param initialArray initial array
* @since 2.2
*/
public ResizableDoubleArray(double[] initialArray) {
this(DEFAULT_INITIAL_CAPACITY,
DEFAULT_EXPANSION_FACTOR,
DEFAULT_CONTRACTION_DELTA + DEFAULT_EXPANSION_FACTOR,
ExpansionMode.MULTIPLICATIVE,
initialArray);
}
/**
* Creates an instance with the specified initial capacity
* and expansion factor.
* The remaining properties take default values:
*
* - {@code expansionMode = MULTIPLICATIVE}
* - {@code contractionCriterion = 0.5 + expansionFactor}
*
*
* Throws IllegalArgumentException if the following conditions are
* not met:
*
* - {@code initialCapacity > 0}
* - {@code expansionFactor > 1}
*
*
* @param initialCapacity Initial size of the internal storage array.
* @param expansionFactor The array will be expanded based on this
* parameter.
* @throws MathIllegalArgumentException if parameters are not valid.
* @deprecated As of 3.1. Please use
* {@link #ResizableDoubleArray(int,double)} instead.
*/
@Deprecated
public ResizableDoubleArray(int initialCapacity,
float expansionFactor)
throws MathIllegalArgumentException {
this(initialCapacity,
(double) expansionFactor);
}
/**
* Creates an instance with the specified initial capacity
* and expansion factor.
* The remaining properties take default values:
*
* - {@code expansionMode = MULTIPLICATIVE}
* - {@code contractionCriterion = 0.5 + expansionFactor}
*
*
* Throws IllegalArgumentException if the following conditions are
* not met:
*
* - {@code initialCapacity > 0}
* - {@code expansionFactor > 1}
*
*
* @param initialCapacity Initial size of the internal storage array.
* @param expansionFactor The array will be expanded based on this
* parameter.
* @throws MathIllegalArgumentException if parameters are not valid.
* @since 3.1
*/
public ResizableDoubleArray(int initialCapacity,
double expansionFactor)
throws MathIllegalArgumentException {
this(initialCapacity,
expansionFactor,
DEFAULT_CONTRACTION_DELTA + expansionFactor);
}
/**
* Creates an instance with the specified initialCapacity,
* expansionFactor, and contractionCriterion.
* The expansion mode will default to {@code MULTIPLICATIVE}.
*
* Throws IllegalArgumentException if the following conditions are
* not met:
*
* - {@code initialCapacity > 0}
* - {@code expansionFactor > 1}
* - {@code contractionCriterion >= expansionFactor}
*
*
* @param initialCapacity Initial size of the internal storage array..
* @param expansionFactor The array will be expanded based on this
* parameter.
* @param contractionCriteria Contraction criteria.
* @throws MathIllegalArgumentException if parameters are not valid.
* @deprecated As of 3.1. Please use
* {@link #ResizableDoubleArray(int,double,double)} instead.
*/
@Deprecated
public ResizableDoubleArray(int initialCapacity,
float expansionFactor,
float contractionCriteria)
throws MathIllegalArgumentException {
this(initialCapacity,
(double) expansionFactor,
(double) contractionCriteria);
}
/**
* Creates an instance with the specified initial capacity,
* expansion factor, and contraction criteria.
* The expansion mode will default to {@code MULTIPLICATIVE}.
*
* Throws IllegalArgumentException if the following conditions are
* not met:
*
* - {@code initialCapacity > 0}
* - {@code expansionFactor > 1}
* - {@code contractionCriterion >= expansionFactor}
*
*
* @param initialCapacity Initial size of the internal storage array..
* @param expansionFactor The array will be expanded based on this
* parameter.
* @param contractionCriterion Contraction criterion.
* @throws MathIllegalArgumentException if the parameters are not valid.
* @since 3.1
*/
public ResizableDoubleArray(int initialCapacity,
double expansionFactor,
double contractionCriterion)
throws MathIllegalArgumentException {
this(initialCapacity,
expansionFactor,
contractionCriterion,
ExpansionMode.MULTIPLICATIVE,
null);
}
/**
*
* Create a ResizableArray with the specified properties.
*
* Throws IllegalArgumentException if the following conditions are
* not met:
*
* initialCapacity > 0expansionFactor > 1contractionFactor >= expansionFactorexpansionMode in {MULTIPLICATIVE_MODE, ADDITIVE_MODE}
*
*
* @param initialCapacity the initial size of the internal storage array
* @param expansionFactor the array will be expanded based on this
* parameter
* @param contractionCriteria the contraction Criteria
* @param expansionMode the expansion mode
* @throws MathIllegalArgumentException if parameters are not valid
* @deprecated As of 3.1. Please use
* {@link #ResizableDoubleArray(int,double,double,ExpansionMode,double[])}
* instead.
*/
@Deprecated
public ResizableDoubleArray(int initialCapacity, float expansionFactor,
float contractionCriteria, int expansionMode) throws MathIllegalArgumentException {
this(initialCapacity,
expansionFactor,
contractionCriteria,
expansionMode == ADDITIVE_MODE ?
ExpansionMode.ADDITIVE :
ExpansionMode.MULTIPLICATIVE,
null);
// XXX Just ot retain the expected failure in a unit test.
// With the new "enum", that test will become obsolete.
setExpansionMode(expansionMode);
}
/**
* Creates an instance with the specified properties.
*
* Throws MathIllegalArgumentException if the following conditions are
* not met:
*
* - {@code initialCapacity > 0}
* - {@code expansionFactor > 1}
* - {@code contractionCriterion >= expansionFactor}
*
*
* @param initialCapacity Initial size of the internal storage array.
* @param expansionFactor The array will be expanded based on this
* parameter.
* @param contractionCriterion Contraction criteria.
* @param expansionMode Expansion mode.
* @param data Initial contents of the array.
* @throws MathIllegalArgumentException if the parameters are not valid.
*/
public ResizableDoubleArray(int initialCapacity,
double expansionFactor,
double contractionCriterion,
ExpansionMode expansionMode,
double ... data)
throws MathIllegalArgumentException {
if (initialCapacity <= 0) {
throw new NotStrictlyPositiveException(LocalizedFormats.INITIAL_CAPACITY_NOT_POSITIVE,
initialCapacity);
}
checkContractExpand(contractionCriterion, expansionFactor);
this.expansionFactor = expansionFactor;
this.contractionCriterion = contractionCriterion;
this.expansionMode = expansionMode;
internalArray = new double[initialCapacity];
numElements = 0;
startIndex = 0;
if (data != null && data.length > 0) {
addElements(data);
}
}
/**
* Copy constructor. Creates a new ResizableDoubleArray that is a deep,
* fresh copy of the original. Needs to acquire synchronization lock
* on original. Original may not be null; otherwise a {@link NullArgumentException}
* is thrown.
*
* @param original array to copy
* @exception NullArgumentException if original is null
* @since 2.0
*/
public ResizableDoubleArray(ResizableDoubleArray original)
throws NullArgumentException {
MathUtils.checkNotNull(original);
copy(original, this);
}
/**
* Adds an element to the end of this expandable array.
*
* @param value Value to be added to end of array.
*/
public synchronized void addElement(double value) {
if (internalArray.length <= startIndex + numElements) {
expand();
}
internalArray[startIndex + numElements++] = value;
}
/**
* Adds several element to the end of this expandable array.
*
* @param values Values to be added to end of array.
* @since 2.2
*/
public synchronized void addElements(double[] values) {
final double[] tempArray = new double[numElements + values.length + 1];
System.arraycopy(internalArray, startIndex, tempArray, 0, numElements);
System.arraycopy(values, 0, tempArray, numElements, values.length);
internalArray = tempArray;
startIndex = 0;
numElements += values.length;
}
/**
*
* Adds an element to the end of the array and removes the first
* element in the array. Returns the discarded first element.
* The effect is similar to a push operation in a FIFO queue.
*
*
* Example: If the array contains the elements 1, 2, 3, 4 (in that order)
* and addElementRolling(5) is invoked, the result is an array containing
* the entries 2, 3, 4, 5 and the value returned is 1.
*
*
* @param value Value to be added to the array.
* @return the value which has been discarded or "pushed" out of the array
* by this rolling insert.
*/
public synchronized double addElementRolling(double value) {
double discarded = internalArray[startIndex];
if ((startIndex + (numElements + 1)) > internalArray.length) {
expand();
}
// Increment the start index
startIndex += 1;
// Add the new value
internalArray[startIndex + (numElements - 1)] = value;
// Check the contraction criterion.
if (shouldContract()) {
contract();
}
return discarded;
}
/**
* Substitutes value for the most recently added value.
* Returns the value that has been replaced. If the array is empty (i.e.
* if {@link #numElements} is zero), an IllegalStateException is thrown.
*
* @param value New value to substitute for the most recently added value
* @return the value that has been replaced in the array.
* @throws MathIllegalStateException if the array is empty
* @since 2.0
*/
public synchronized double substituteMostRecentElement(double value)
throws MathIllegalStateException {
if (numElements < 1) {
throw new MathIllegalStateException(
LocalizedFormats.CANNOT_SUBSTITUTE_ELEMENT_FROM_EMPTY_ARRAY);
}
final int substIndex = startIndex + (numElements - 1);
final double discarded = internalArray[substIndex];
internalArray[substIndex] = value;
return discarded;
}
/**
* Checks the expansion factor and the contraction criterion and throws an
* IllegalArgumentException if the contractionCriteria is less than the
* expansionCriteria
*
* @param expansion factor to be checked
* @param contraction criteria to be checked
* @throws MathIllegalArgumentException if the contractionCriteria is less than
* the expansionCriteria.
* @deprecated As of 3.1. Please use
* {@link #checkContractExpand(double,double)} instead.
*/
@Deprecated
protected void checkContractExpand(float contraction, float expansion)
throws MathIllegalArgumentException {
checkContractExpand((double) contraction,
(double) expansion);
}
/**
* Checks the expansion factor and the contraction criterion and raises
* an exception if the contraction criterion is smaller than the
* expansion criterion.
*
* @param contraction Criterion to be checked.
* @param expansion Factor to be checked.
* @throws NumberIsTooSmallException if {@code contraction < expansion}.
* @throws NumberIsTooSmallException if {@code contraction <= 1}.
* @throws NumberIsTooSmallException if {@code expansion <= 1 }.
* @since 3.1
*/
protected void checkContractExpand(double contraction,
double expansion)
throws NumberIsTooSmallException {
if (contraction < expansion) {
final NumberIsTooSmallException e = new NumberIsTooSmallException(contraction, 1, true);
e.getContext().addMessage(LocalizedFormats.CONTRACTION_CRITERIA_SMALLER_THAN_EXPANSION_FACTOR,
contraction, expansion);
throw e;
}
if (contraction <= 1) {
final NumberIsTooSmallException e = new NumberIsTooSmallException(contraction, 1, false);
e.getContext().addMessage(LocalizedFormats.CONTRACTION_CRITERIA_SMALLER_THAN_ONE,
contraction);
throw e;
}
if (expansion <= 1) {
final NumberIsTooSmallException e = new NumberIsTooSmallException(contraction, 1, false);
e.getContext().addMessage(LocalizedFormats.EXPANSION_FACTOR_SMALLER_THAN_ONE,
expansion);
throw e;
}
}
/**
* Clear the array contents, resetting the number of elements to zero.
*/
public synchronized void clear() {
numElements = 0;
startIndex = 0;
}
/**
* Contracts the storage array to the (size of the element set) + 1 - to
* avoid a zero length array. This function also resets the startIndex to
* zero.
*/
public synchronized void contract() {
final double[] tempArray = new double[numElements + 1];
// Copy and swap - copy only the element array from the src array.
System.arraycopy(internalArray, startIndex, tempArray, 0, numElements);
internalArray = tempArray;
// Reset the start index to zero
startIndex = 0;
}
/**
* Discards the i initial elements of the array. For example,
* if the array contains the elements 1,2,3,4, invoking
* discardFrontElements(2) will cause the first two elements
* to be discarded, leaving 3,4 in the array. Throws illegalArgumentException
* if i exceeds numElements.
*
* @param i the number of elements to discard from the front of the array
* @throws MathIllegalArgumentException if i is greater than numElements.
* @since 2.0
*/
public synchronized void discardFrontElements(int i)
throws MathIllegalArgumentException {
discardExtremeElements(i,true);
}
/**
* Discards the i last elements of the array. For example,
* if the array contains the elements 1,2,3,4, invoking
* discardMostRecentElements(2) will cause the last two elements
* to be discarded, leaving 1,2 in the array. Throws illegalArgumentException
* if i exceeds numElements.
*
* @param i the number of elements to discard from the end of the array
* @throws MathIllegalArgumentException if i is greater than numElements.
* @since 2.0
*/
public synchronized void discardMostRecentElements(int i)
throws MathIllegalArgumentException {
discardExtremeElements(i,false);
}
/**
* Discards the i first or last elements of the array,
* depending on the value of front.
* For example, if the array contains the elements 1,2,3,4, invoking
* discardExtremeElements(2,false) will cause the last two elements
* to be discarded, leaving 1,2 in the array.
* For example, if the array contains the elements 1,2,3,4, invoking
* discardExtremeElements(2,true) will cause the first two elements
* to be discarded, leaving 3,4 in the array.
* Throws illegalArgumentException
* if i exceeds numElements.
*
* @param i the number of elements to discard from the front/end of the array
* @param front true if elements are to be discarded from the front
* of the array, false if elements are to be discarded from the end
* of the array
* @throws MathIllegalArgumentException if i is greater than numElements.
* @since 2.0
*/
private synchronized void discardExtremeElements(int i,
boolean front)
throws MathIllegalArgumentException {
if (i > numElements) {
throw new MathIllegalArgumentException(
LocalizedFormats.TOO_MANY_ELEMENTS_TO_DISCARD_FROM_ARRAY,
i, numElements);
} else if (i < 0) {
throw new MathIllegalArgumentException(
LocalizedFormats.CANNOT_DISCARD_NEGATIVE_NUMBER_OF_ELEMENTS,
i);
} else {
// "Subtract" this number of discarded from numElements
numElements -= i;
if (front) {
startIndex += i;
}
}
if (shouldContract()) {
contract();
}
}
/**
* Expands the internal storage array using the expansion factor.
*
* if expansionMode is set to MULTIPLICATIVE_MODE,
* the new array size will be internalArray.length * expansionFactor.
* If expansionMode is set to ADDITIVE_MODE, the length
* after expansion will be internalArray.length + expansionFactor
*
*/
protected synchronized void expand() {
// notice the use of FastMath.ceil(), this guarantees that we will always
// have an array of at least currentSize + 1. Assume that the
// current initial capacity is 1 and the expansion factor
// is 1.000000000000000001. The newly calculated size will be
// rounded up to 2 after the multiplication is performed.
int newSize = 0;
if (expansionMode == ExpansionMode.MULTIPLICATIVE) {
newSize = (int) FastMath.ceil(internalArray.length * expansionFactor);
} else {
newSize = (int) (internalArray.length + FastMath.round(expansionFactor));
}
final double[] tempArray = new double[newSize];
// Copy and swap
System.arraycopy(internalArray, 0, tempArray, 0, internalArray.length);
internalArray = tempArray;
}
/**
* Expands the internal storage array to the specified size.
*
* @param size Size of the new internal storage array.
*/
private synchronized void expandTo(int size) {
final double[] tempArray = new double[size];
// Copy and swap
System.arraycopy(internalArray, 0, tempArray, 0, internalArray.length);
internalArray = tempArray;
}
/**
* The contraction criteria defines when the internal array will contract
* to store only the number of elements in the element array.
* If the expansionMode is MULTIPLICATIVE_MODE,
* contraction is triggered when the ratio between storage array length
* and numElements exceeds contractionFactor.
* If the expansionMode is ADDITIVE_MODE, the
* number of excess storage locations is compared to
* contractionFactor.
*
* @return the contraction criteria used to reclaim memory.
* @deprecated As of 3.1. Please use {@link #getContractionCriterion()}
* instead.
*/
@Deprecated
public float getContractionCriteria() {
return (float) getContractionCriterion();
}
/**
* The contraction criterion defines when the internal array will contract
* to store only the number of elements in the element array.
* If the expansionMode is MULTIPLICATIVE_MODE,
* contraction is triggered when the ratio between storage array length
* and numElements exceeds contractionFactor.
* If the expansionMode is ADDITIVE_MODE, the
* number of excess storage locations is compared to
* contractionFactor.
*
* @return the contraction criterion used to reclaim memory.
* @since 3.1
*/
public double getContractionCriterion() {
return contractionCriterion;
}
/**
* Returns the element at the specified index
*
* @param index index to fetch a value from
* @return value stored at the specified index
* @throws ArrayIndexOutOfBoundsException if index is less than
* zero or is greater than getNumElements() - 1.
*/
public synchronized double getElement(int index) {
if (index >= numElements) {
throw new ArrayIndexOutOfBoundsException(index);
} else if (index >= 0) {
return internalArray[startIndex + index];
} else {
throw new ArrayIndexOutOfBoundsException(index);
}
}
/**
* Returns a double array containing the elements of this
* ResizableArray. This method returns a copy, not a
* reference to the underlying array, so that changes made to the returned
* array have no effect on this ResizableArray.
* @return the double array.
*/
public synchronized double[] getElements() {
final double[] elementArray = new double[numElements];
System.arraycopy(internalArray, startIndex, elementArray, 0, numElements);
return elementArray;
}
/**
* The expansion factor controls the size of a new array when an array
* needs to be expanded. The expansionMode
* determines whether the size of the array is multiplied by the
* expansionFactor (MULTIPLICATIVE_MODE) or if
* the expansion is additive (ADDITIVE_MODE -- expansionFactor
* storage locations added). The default expansionMode is
* MULTIPLICATIVE_MODE and the default expansionFactor
* is 2.0.
*
* @return the expansion factor of this expandable double array
* @deprecated As of 3.1. Return type will be changed to "double" in 4.0.
*/
@Deprecated
public float getExpansionFactor() {
return (float) expansionFactor;
}
/**
* The expansion mode determines whether the internal storage
* array grows additively or multiplicatively when it is expanded.
*
* @return the expansion mode.
* @deprecated As of 3.1. Return value to be changed to
* {@link ExpansionMode} in 4.0.
*/
@Deprecated
public int getExpansionMode() {
synchronized (this) {
switch (expansionMode) {
case MULTIPLICATIVE:
return MULTIPLICATIVE_MODE;
case ADDITIVE:
return ADDITIVE_MODE;
default:
throw new MathInternalError(); // Should never happen.
}
}
}
/**
* Notice the package scope on this method. This method is simply here
* for the JUnit test, it allows us check if the expansion is working
* properly after a number of expansions. This is not meant to be a part
* of the public interface of this class.
*
* @return the length of the internal storage array.
* @deprecated As of 3.1. Please use {@link #getCapacity()} instead.
*/
@Deprecated
synchronized int getInternalLength() {
return internalArray.length;
}
/**
* Gets the currently allocated size of the internal data structure used
* for storing elements.
* This is not to be confused with {@link #getNumElements() the number of
* elements actually stored}.
*
* @return the length of the internal array.
* @since 3.1
*/
public int getCapacity() {
return internalArray.length;
}
/**
* Returns the number of elements currently in the array. Please note
* that this is different from the length of the internal storage array.
*
* @return the number of elements.
*/
public synchronized int getNumElements() {
return numElements;
}
/**
* Returns the internal storage array. Note that this method returns
* a reference to the internal storage array, not a copy, and to correctly
* address elements of the array, the startIndex is
* required (available via the {@link #start} method). This method should
* only be used in cases where copying the internal array is not practical.
* The {@link #getElements} method should be used in all other cases.
*
*
* @return the internal storage array used by this object
* @since 2.0
* @deprecated As of 3.1.
*/
@Deprecated
public synchronized double[] getInternalValues() {
return internalArray;
}
/**
* Provides direct access to the internal storage array.
* Please note that this method returns a reference to this object's
* storage array, not a copy.
*
* To correctly address elements of the array, the "start index" is
* required (available via the {@link #getStartIndex() getStartIndex}
* method.
*
* This method should only be used to avoid copying the internal array.
* The returned value must be used for reading only; other
* uses could lead to this object becoming inconsistent.
*
* The {@link #getElements} method has no such limitation since it
* returns a copy of this array's addressable elements.
*
* @return the internal storage array used by this object.
* @since 3.1
*/
protected double[] getArrayRef() {
return internalArray;
}
/**
* Returns the "start index" of the internal array.
* This index is the position of the first addressable element in the
* internal storage array.
* The addressable elements in the array are at indices contained in
* the interval [{@link #getStartIndex()},
* {@link #getStartIndex()} + {@link #getNumElements()} - 1].
*
* @return the start index.
* @since 3.1
*/
protected int getStartIndex() {
return startIndex;
}
/**
* Sets the contraction criteria.
*
* @param contractionCriteria contraction criteria
* @throws MathIllegalArgumentException if the contractionCriteria is less than
* the expansionCriteria.
* @deprecated As of 3.1 (to be removed in 4.0 as field will become "final").
*/
@Deprecated
public void setContractionCriteria(float contractionCriteria)
throws MathIllegalArgumentException {
checkContractExpand(contractionCriteria, getExpansionFactor());
synchronized(this) {
this.contractionCriterion = contractionCriteria;
}
}
/**
* Performs an operation on the addressable elements of the array.
*
* @param f Function to be applied on this array.
* @return the result.
* @since 3.1
*/
public double compute(MathArrays.Function f) {
final double[] array;
final int start;
final int num;
synchronized(this) {
array = internalArray;
start = startIndex;
num = numElements;
}
return f.evaluate(array, start, num);
}
/**
* Sets the element at the specified index. If the specified index is greater than
* getNumElements() - 1, the numElements property
* is increased to index +1 and additional storage is allocated
* (if necessary) for the new element and all (uninitialized) elements
* between the new element and the previous end of the array).
*
* @param index index to store a value in
* @param value value to store at the specified index
* @throws ArrayIndexOutOfBoundsException if {@code index < 0}.
*/
public synchronized void setElement(int index, double value) {
if (index < 0) {
throw new ArrayIndexOutOfBoundsException(index);
}
if (index + 1 > numElements) {
numElements = index + 1;
}
if ((startIndex + index) >= internalArray.length) {
expandTo(startIndex + (index + 1));
}
internalArray[startIndex + index] = value;
}
/**
* Sets the expansionFactor. Throws IllegalArgumentException if the
* the following conditions are not met:
*
* expansionFactor > 1contractionFactor >= expansionFactor
* @param expansionFactor the new expansion factor value.
* @throws MathIllegalArgumentException if expansionFactor is <= 1 or greater
* than contractionFactor
* @deprecated As of 3.1 (to be removed in 4.0 as field will become "final").
*/
@Deprecated
public void setExpansionFactor(float expansionFactor) throws MathIllegalArgumentException {
checkContractExpand(getContractionCriterion(), expansionFactor);
// The check above verifies that the expansion factor is > 1.0;
synchronized(this) {
this.expansionFactor = expansionFactor;
}
}
/**
* Sets the expansionMode. The specified value must be one of
* ADDITIVE_MODE, MULTIPLICATIVE_MODE.
*
* @param expansionMode The expansionMode to set.
* @throws MathIllegalArgumentException if the specified mode value is not valid.
* @deprecated As of 3.1. Please use {@link #setExpansionMode(ExpansionMode)} instead.
*/
@Deprecated
public void setExpansionMode(int expansionMode)
throws MathIllegalArgumentException {
if (expansionMode != MULTIPLICATIVE_MODE &&
expansionMode != ADDITIVE_MODE) {
throw new MathIllegalArgumentException(LocalizedFormats.UNSUPPORTED_EXPANSION_MODE, expansionMode,
MULTIPLICATIVE_MODE, "MULTIPLICATIVE_MODE",
ADDITIVE_MODE, "ADDITIVE_MODE");
}
synchronized(this) {
if (expansionMode == MULTIPLICATIVE_MODE) {
setExpansionMode(ExpansionMode.MULTIPLICATIVE);
} else if (expansionMode == ADDITIVE_MODE) {
setExpansionMode(ExpansionMode.ADDITIVE);
}
}
}
/**
* Sets the {@link ExpansionMode expansion mode}.
*
* @param expansionMode Expansion mode to use for resizing the array.
* @deprecated As of 3.1 (to be removed in 4.0 as field will become "final").
*/
@Deprecated
public void setExpansionMode(ExpansionMode expansionMode) {
synchronized(this) {
this.expansionMode = expansionMode;
}
}
/**
* Sets the initial capacity. Should only be invoked by constructors.
*
* @param initialCapacity of the array
* @throws MathIllegalArgumentException if initialCapacity is not
* positive.
* @deprecated As of 3.1, this is a no-op.
*/
@Deprecated
protected void setInitialCapacity(int initialCapacity)
throws MathIllegalArgumentException {
// Body removed in 3.1.
}
/**
* This function allows you to control the number of elements contained
* in this array, and can be used to "throw out" the last n values in an
* array. This function will also expand the internal array as needed.
*
* @param i a new number of elements
* @throws MathIllegalArgumentException if i is negative.
*/
public synchronized void setNumElements(int i)
throws MathIllegalArgumentException {
// If index is negative thrown an error.
if (i < 0) {
throw new MathIllegalArgumentException(
LocalizedFormats.INDEX_NOT_POSITIVE,
i);
}
// Test the new num elements, check to see if the array needs to be
// expanded to accommodate this new number of elements.
final int newSize = startIndex + i;
if (newSize > internalArray.length) {
expandTo(newSize);
}
// Set the new number of elements to new value.
numElements = i;
}
/**
* Returns true if the internal storage array has too many unused
* storage positions.
*
* @return true if array satisfies the contraction criteria
*/
private synchronized boolean shouldContract() {
if (expansionMode == ExpansionMode.MULTIPLICATIVE) {
return (internalArray.length / ((float) numElements)) > contractionCriterion;
} else {
return (internalArray.length - numElements) > contractionCriterion;
}
}
/**
* Returns the starting index of the internal array. The starting index is
* the position of the first addressable element in the internal storage
* array. The addressable elements in the array are
* internalArray[startIndex],...,internalArray[startIndex + numElements -1]
*
*
* @return the starting index.
* @deprecated As of 3.1.
*/
@Deprecated
public synchronized int start() {
return startIndex;
}
/**
* Copies source to dest, copying the underlying data, so dest is
* a new, independent copy of source. Does not contract before
* the copy.
*
* Obtains synchronization locks on both source and dest
* (in that order) before performing the copy.
*
* Neither source nor dest may be null; otherwise a {@link NullArgumentException}
* is thrown
*
* @param source ResizableDoubleArray to copy
* @param dest ResizableArray to replace with a copy of the source array
* @exception NullArgumentException if either source or dest is null
* @since 2.0
*
*/
public static void copy(ResizableDoubleArray source,
ResizableDoubleArray dest)
throws NullArgumentException {
MathUtils.checkNotNull(source);
MathUtils.checkNotNull(dest);
synchronized(source) {
synchronized(dest) {
dest.contractionCriterion = source.contractionCriterion;
dest.expansionFactor = source.expansionFactor;
dest.expansionMode = source.expansionMode;
dest.internalArray = new double[source.internalArray.length];
System.arraycopy(source.internalArray, 0, dest.internalArray,
0, dest.internalArray.length);
dest.numElements = source.numElements;
dest.startIndex = source.startIndex;
}
}
}
/**
* Returns a copy of the ResizableDoubleArray. Does not contract before
* the copy, so the returned object is an exact copy of this.
*
* @return a new ResizableDoubleArray with the same data and configuration
* properties as this
* @since 2.0
*/
public synchronized ResizableDoubleArray copy() {
final ResizableDoubleArray result = new ResizableDoubleArray();
copy(this, result);
return result;
}
/**
* Returns true iff object is a ResizableDoubleArray with the same properties
* as this and an identical internal storage array.
*
* @param object object to be compared for equality with this
* @return true iff object is a ResizableDoubleArray with the same data and
* properties as this
* @since 2.0
*/
@Override
public boolean equals(Object object) {
if (object == this ) {
return true;
}
if (object instanceof ResizableDoubleArray == false) {
return false;
}
synchronized(this) {
synchronized(object) {
boolean result = true;
final ResizableDoubleArray other = (ResizableDoubleArray) object;
result = result && (other.contractionCriterion == contractionCriterion);
result = result && (other.expansionFactor == expansionFactor);
result = result && (other.expansionMode == expansionMode);
result = result && (other.numElements == numElements);
result = result && (other.startIndex == startIndex);
if (!result) {
return false;
} else {
return Arrays.equals(internalArray, other.internalArray);
}
}
}
}
/**
* Returns a hash code consistent with equals.
*
* @return the hash code representing this {@code ResizableDoubleArray}.
* @since 2.0
*/
@Override
public synchronized int hashCode() {
final int[] hashData = new int[6];
hashData[0] = Double.valueOf(expansionFactor).hashCode();
hashData[1] = Double.valueOf(contractionCriterion).hashCode();
hashData[2] = expansionMode.hashCode();
hashData[3] = Arrays.hashCode(internalArray);
hashData[4] = numElements;
hashData[5] = startIndex;
return Arrays.hashCode(hashData);
}
}
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