ResizableDoubleArray.java
/*
* 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.legacy.stat.descriptive;
import java.util.Arrays;
import org.apache.commons.math4.legacy.exception.MathIllegalArgumentException;
import org.apache.commons.math4.legacy.exception.MathIllegalStateException;
import org.apache.commons.math4.legacy.exception.NotStrictlyPositiveException;
import org.apache.commons.math4.legacy.exception.NullArgumentException;
import org.apache.commons.math4.legacy.exception.NumberIsTooSmallException;
import org.apache.commons.math4.legacy.exception.util.LocalizedFormats;
import org.apache.commons.math4.core.jdkmath.JdkMath;
import org.apache.commons.math4.legacy.core.MathArrays;
/**
* A variable length {@link DoubleArray} implementation that automatically
* handles expanding and contracting its internal storage array as elements
* are added and removed.
* <p>
* 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.
* <p>
* 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}.
* <p>
* 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.
* <p>
* <b>Note:</b> this class is <b>NOT</b> thread-safe.
*/
class ResizableDoubleArray implements DoubleArray { // Not in public API.
/** 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 expansion mode. */
private static final ExpansionMode DEFAULT_EXPANSION_MODE = ExpansionMode.MULTIPLICATIVE;
/**
* 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 final double contractionCriterion;
/**
* 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, or
* {@code internalArray.length + expansionFactor} if
* {@code expansionMode} is set to ADDITIVE.
*/
private final double expansionFactor;
/**
* Determines whether array expansion by {@code expansionFactor}
* is additive or multiplicative.
*/
private final ExpansionMode expansionMode;
/**
* 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;
/**
* 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;
/**
* Specification of expansion algorithm.
* @since 3.1
*/
public enum ExpansionMode {
/** Multiplicative expansion mode. */
MULTIPLICATIVE,
/** Additive expansion mode. */
ADDITIVE
}
/**
* Creates an instance with default properties.
* <ul>
* <li>{@code initialCapacity = 16}</li>
* <li>{@code expansionMode = MULTIPLICATIVE}</li>
* <li>{@code expansionFactor = 2.0}</li>
* <li>{@code contractionCriterion = 2.5}</li>
* </ul>
*/
ResizableDoubleArray() {
this(DEFAULT_INITIAL_CAPACITY);
}
/**
* Creates an instance with the specified initial capacity.
* <p>
* Other properties take default values:
* <ul>
* <li>{@code expansionMode = MULTIPLICATIVE}</li>
* <li>{@code expansionFactor = 2.0}</li>
* <li>{@code contractionCriterion = 2.5}</li>
* </ul>
* @param initialCapacity Initial size of the internal storage array.
* @throws MathIllegalArgumentException if {@code initialCapacity <= 0}.
*/
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.
* <p>
* 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:
* <ul>
* <li>{@code expansionMode = MULTIPLICATIVE}</li>
* <li>{@code expansionFactor = 2.0}</li>
* <li>{@code contractionCriterion = 2.5}</li>
* </ul>
*
* @param initialArray initial array
* @since 2.2
*/
ResizableDoubleArray(double[] initialArray) {
this(initialArray == null || initialArray.length == 0 ?
DEFAULT_INITIAL_CAPACITY :
initialArray.length,
DEFAULT_EXPANSION_FACTOR,
DEFAULT_CONTRACTION_DELTA + DEFAULT_EXPANSION_FACTOR,
DEFAULT_EXPANSION_MODE,
initialArray);
}
/**
* Creates an instance with the specified initial capacity
* and expansion factor.
* <p>
* The remaining properties take default values:
* <ul>
* <li>{@code expansionMode = MULTIPLICATIVE}</li>
* <li>{@code contractionCriterion = 0.5 + expansionFactor}</li>
* </ul>
* <p>
* Throws MathIllegalArgumentException if the following conditions
* are not met:
* <ul>
* <li>{@code initialCapacity > 0}</li>
* <li>{@code expansionFactor > 1}</li>
* </ul>
*
* @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
*/
ResizableDoubleArray(int initialCapacity, double expansionFactor) throws MathIllegalArgumentException {
this(initialCapacity, expansionFactor, DEFAULT_CONTRACTION_DELTA + expansionFactor);
}
/**
* Creates an instance with the specified initial capacity,
* expansion factor, and contraction criteria.
* <p>
* The expansion mode will default to {@code MULTIPLICATIVE}.
* <p>
* Throws MathIllegalArgumentException if the following conditions
* are not met:
* <ul>
* <li>{@code initialCapacity > 0}</li>
* <li>{@code expansionFactor > 1}</li>
* <li>{@code contractionCriterion >= expansionFactor}</li>
* </ul>
*
* @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
*/
ResizableDoubleArray(int initialCapacity, double expansionFactor, double contractionCriterion)
throws MathIllegalArgumentException {
this(initialCapacity, expansionFactor, contractionCriterion, DEFAULT_EXPANSION_MODE);
}
/**
* Creates an instance with the specified properties.
* <br>
* Throws MathIllegalArgumentException if the following conditions
* are not met:
* <ul>
* <li>{@code initialCapacity > 0}</li>
* <li>{@code expansionFactor > 1}</li>
* <li>{@code contractionCriterion >= expansionFactor}</li>
* </ul>
*
* @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.
* @throws NullArgumentException if expansionMode is null
*/
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);
NullArgumentException.check(expansionMode);
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.
* <p>
* Creates a new ResizableDoubleArray that is a deep, fresh copy of the 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
*/
ResizableDoubleArray(final ResizableDoubleArray original)
throws NullArgumentException {
NullArgumentException.check(original);
this.contractionCriterion = original.contractionCriterion;
this.expansionFactor = original.expansionFactor;
this.expansionMode = original.expansionMode;
this.internalArray = new double[original.internalArray.length];
System.arraycopy(original.internalArray, 0, this.internalArray, 0, this.internalArray.length);
this.numElements = original.numElements;
this.startIndex = original.startIndex;
}
/**
* Adds an element to the end of this expandable array.
*
* @param value Value to be added to end of array.
*/
@Override
public void addElement(final 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
*/
@Override
public void addElements(final 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.
* <p>
* The effect is similar to a push operation in a FIFO queue.
* <p>
* 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.
*/
@Override
public 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 {@code value} for the most recently added value.
* <p>
* Returns the value that has been replaced. If the array is empty (i.e.
* if {@link #numElements} is zero), an MathIllegalStateException 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 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 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.
*/
@Override
public 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 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 {@code i} initial elements of the array.
* <p>
* For example, if the array contains the elements 1,2,3,4, invoking
* {@code discardFrontElements(2)} will cause the first two elements
* to be discarded, leaving 3,4 in the array.
*
* @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 void discardFrontElements(int i) throws MathIllegalArgumentException {
discardExtremeElements(i,true);
}
/**
* Discards the {@code i} last elements of the array.
* <p>
* For example, if the array contains the elements 1,2,3,4, invoking
* {@code discardMostRecentElements(2)} will cause the last two elements
* to be discarded, leaving 1,2 in the array.
*
* @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 void discardMostRecentElements(int i) throws MathIllegalArgumentException {
discardExtremeElements(i,false);
}
/**
* Discards the {@code i} first or last elements of the array,
* depending on the value of {@code front}.
* <p>
* For example, if the array contains the elements 1,2,3,4, invoking
* {@code 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
* {@code discardExtremeElements(2,true)} will cause the first two elements
* to be discarded, leaving 3,4 in the array.
*
* @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 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.
* <p>
* If {@code expansionMode} is set to MULTIPLICATIVE,
* the new array size will be {@code internalArray.length * expansionFactor}.
* If {@code expansionMode} is set to ADDITIVE, the length
* after expansion will be {@code internalArray.length + expansionFactor}.
*/
protected void expand() {
// notice the use of JdkMath.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) JdkMath.ceil(internalArray.length * expansionFactor);
} else {
newSize = (int) (internalArray.length + JdkMath.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 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 criterion defines when the internal array will contract
* to store only the number of elements in the element array.
* <p>
* 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}.
*
* @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 {@code index} is less than
* zero or is greater than {@code getNumElements() - 1}.
*/
@Override
public 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.
* <p>
* 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.
*/
@Override
public 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.
* <p>
* The {@code expansionMode} determines whether the size of the array
* is multiplied by the {@code expansionFactor} (MULTIPLICATIVE) or if
* the expansion is additive (ADDITIVE -- {@code expansionFactor}
* storage locations added). The default {@code expansionMode} is
* MULTIPLICATIVE and the default {@code expansionFactor} is 2.0.
*
* @return the expansion factor of this expandable double array
*/
public double getExpansionFactor() {
return expansionFactor;
}
/**
* The expansion mode determines whether the internal storage
* array grows additively or multiplicatively when it is expanded.
*
* @return the expansion mode.
*/
public ExpansionMode getExpansionMode() {
return expansionMode;
}
/**
* 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.
*/
@Override
public int getNumElements() {
return numElements;
}
/**
* Provides <em>direct</em> access to the internal storage array.
* Please note that this method returns a reference to this object's
* storage array, not a copy.
* <p>
* To correctly address elements of the array, the "start index" is
* required (available via the {@link #getStartIndex() getStartIndex}
* method.
* <p>
* This method should only be used to avoid copying the internal array.
* The returned value <em>must</em> be used for reading only; other
* uses could lead to this object becoming inconsistent.
* <p>
* 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.
* <p>
* 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;
}
/**
* 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) {
return f.evaluate(internalArray, startIndex, numElements);
}
/**
* Sets the element at the specified index.
* <p>
* If the specified index is greater than {@code getNumElements() - 1},
* the {@code numElements} property is increased to {@code 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}.
*/
@Override
public 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;
}
/**
* 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 {@code i} is negative.
*/
public 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 boolean shouldContract() {
if (expansionMode == ExpansionMode.MULTIPLICATIVE) {
return (internalArray.length / ((float) numElements)) > contractionCriterion;
} else {
return (internalArray.length - numElements) > contractionCriterion;
}
}
/**
* 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 ResizableDoubleArray copy() {
return new ResizableDoubleArray(this);
}
/**
* 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)) {
return false;
}
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 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);
}
}