Package org.flag4j.util

Class ArrayUtils

java.lang.Object

org.flag4j.util.ArrayUtils

public final class ArrayUtils
extends Object

This class provides several utility methods useful for array manipulation and copying.

Constructor Summary

Constructors

Modifier	Constructor	Description
private	ArrayUtils()

Method Summary

Modifier and Type	Method	Description
static CNumber[]	applyTransform(double[] src, Function<Double,CNumber> opp)	Applies a transform to an array.
static double[]	applyTransform(double[] src, UnaryOperator<Double> opp)	Applies a transform to an array.
static double[]	applyTransform(CNumber[] src, Function<CNumber,Double> opp)	Applies a transform to an array.
static <T> T[]	applyTransform(T[] src, UnaryOperator<T> opp)	Applies a transform to an array.
static void	arraycopy(double[] src, int srcPos, CNumber[] dest, int destPos, int length)	Performs an array copy similar to System.arraycopy(Object, int, Object, int, int) but creates a deep copy of each element in the source array.
static double[]	asDouble(int[] src, double[] dest)	Converts an array of ints to an array of doubles.
static double[]	asDouble(Integer[] src, double[] dest)	Converts an array of Integers to an array of doubles.
static Double[]	boxed(double[] src)	Converts a primitive array to an array of equivalent boxed type.
static Integer[]	boxed(int[] src)	Converts a primitive array to an array of equivalent boxed type.
static boolean	contains(double[] arr, double key)	Checks if an array contains a specified value.
static boolean[]	contains(double[] src, double... keys)	Checks if a set of keys are in an array.
static boolean	contains(int[] arr, int key)	Checks if an array contains a specified value.
static boolean[]	contains(int[] src, int... keys)	Checks if a set of keys is in an array.
static CNumber[]	copy2CNumber(double[] src, CNumber[] dest)	Converts array to an array of complex numbers.
static CNumber[]	copy2CNumber(int[] src, CNumber[] dest)	Converts array to an array of complex numbers.
static CNumber[]	copy2CNumber(Double[] src, CNumber[] dest)	Converts array to an array of complex numbers.
static CNumber[]	copy2CNumber(Integer[] src, CNumber[] dest)	Converts array to an array of complex numbers.
static CNumber[]	copy2CNumber(String[] src, CNumber[] dest)	Converts array to an array of complex numbers.
static HashMap<Integer,Integer>	createUniqueMapping(int[] arr)	Creates a mapping of unique values in {code arr} to integers such that each unique value is mapped to a unique integer and those integers range from 0 to numUnique(arr) - 1.
static int[][]	deepCopy(int[][] src, int[][] dest)	Creates a deep copy of a 2D array.
static boolean	equals(double[] src1, CNumber[] src2)	Checks if a double array is numerically equal to a complex number array.
static void	fill(double[][] dest, double fillValue)	Fills an array with the specified value;
static void	fill(CNumber[][] dest, CNumber fillValue)	Fills an array with specified value.
static void	fill(CNumber[] dest, double fillValue)	Fills an array with specified value.
static void	fill(CNumber[] dest, double fillValue, int from, int to)	Fills range of an array with specified value.
static void	fill(CNumber[] dest, int start, int end, CNumber fillValue)	Fills an array with specified value.
static int[]	filledArray(int size, int value)	Constructs an array filled with a specific value.
static void	fillZeros(CNumber[][] dest)	Fills an array of complex numbers with zeros.
static int[]	findFirstLast(int[] src, int key)	Finds the first and last index of a specified key within a sorted array.
static double[]	flatten(double[][] src)	Flattens a two-dimensional array.
static int[]	flatten(int[][] src)	Flattens a two-dimensional array.
static CNumber[]	flatten(CNumber[][] src)	Flattens a two-dimensional array.
static double[]	fromDoubleList(List<Double> src)	Converts a list of Doubles objects to a primitive array.
static int[]	fromIntegerList(List<Integer> src)	Converts a list of Integer objects to a primitive array.
static int[]	fromIntegerList(List<Integer> src, int[] dest)	Converts a list of Integer objects to a primitive array.
static <T> T[]	fromList(List<T> src, T[] dest)	Converts a list to an array.
static int	indexOf(int[] arr, int key)	Finds the fist index of the specified key within an array.
static int[]	intRange(int start, int end)	Gets an array filled with integers from start (inclusive) to end (exclusive)
static int[]	intRange(int start, int end, int stride)	Gets an array filled with integers from start (inclusive) to end (exclusive) where each int is repeated stride times.
static double[]	join(double[] src1, double[] src2)	Joins two arrays together.
static int[]	join(int[] src1, int[] src2)	Joins two arrays together.
static boolean	notContains(int[] src, int key)	Checks if a key is in an array.
static int[]	notInAxes(int[] srcAxes, int dim)	Given a list of integers, srcAxes, which is a subset of {0, 1, 2, ...., dim-1} in no particular order, compute the integers which are in {0, 1, 2, ...., dim-1} but not in srcAxes.
static int	numUnique(double[] arr)	Counts the number of unique elements in an array.
static int	numUnique(int[] arr)	Counts the number of unique elements in an array.
static double[]	range(int start, int end)	Gets an array filled with integers from start (inclusive) to end (exclusive)
static int[]	repeat(int numTimes, int[] src)	Repeats an array a specified number of times.
static int[]	shift(int shift, int[] indices)	Shifts all indices in an array by a specified amount.
static int[]	shiftRange(int shift, int[] indices, int start, int stop)	Shifts a range of indices in an array by a specified amount.
static double[]	splice(double[] arr1, double[] arr2, int spliceIdx)	Splices an array into another array at the specified index.
static CNumber[]	splice(double[] arr1, CNumber[] arr2, int spliceIdx)	Splices an array into another array at the specified index.
static int[]	splice(int[] arr1, int[] arr2, int spliceIdx)	Splices an array into another array at the specified index.
static double[]	splice(List<Double> list, double[] arr, int spliceIdx)	Splices an array into a list at the specified index.
static int[]	splice(List<Integer> list, int[] arr, int spliceIdx)	Splices an array into a list at the specified index.
static CNumber[]	splice(List<CNumber> list, CNumber[] arr, int spliceIdx)	Splices an array into a list at the specified index.
static CNumber[]	splice(CNumber[] arr1, double[] arr2, int spliceIdx)	Splices an array into another array at the specified index.
static CNumber[]	splice(CNumber[] arr1, CNumber[] arr2, int spliceIdx)	Splices an array into another array at the specified index.
static CNumber[]	spliceDouble(List<CNumber> list, double[] arr, int spliceIdx)	Splices an array into a list at the specified index.
static void	stridedFillZeros(double[] dest, int start, int stride)	Fills an array with zeros separated by the given stride.
static void	stridedFillZeros(double[] dest, int start, int length, int stride)	Fills an array with a range of zeros, each separated by the given stride.
static void	stridedFillZeros(CNumber[] dest, int start, int stride)	Fills an array with zeros separated by the given stride.
static void	stridedFillZeros(CNumber[] dest, int start, int length, int stride)	Fills an array with a range of zeros, each separated by the given stride.
static void	swap(double[] arr, int i, int j)	Swaps to elements in an array.
static void	swap(int[] src, int[] indices)	Swaps elements in an array according to a specified permutation.
static void	swap(int[] arr, int i, int j)	Swaps to elements in an array.
static void	swap(Object[] arr, int i, int j)	Swaps to elements in an array.
static void	swapUnsafe(int[] src, int[] indices)	Swaps elements in an array according to a specified permutation.
static ArrayList<Double>	toArrayList(double[] src)	Converts an array of doubles to an array list.
static ArrayList<Integer>	toArrayList(int[] src)	Converts an array of doubles to an array list.
static ArrayList<CNumber>	toArrayList(CNumber[] src)	Converts an array of complex numbers to an array list.
static ArrayList<CNumber>	toComplexArrayList(double[] src)	Converts an array of doubles to a complex array list.
static double[]	unbox(Double[] arr)	Converts an array of Double objects to a primitive array (i.e.
static int[]	unbox(Integer[] arr)	Converts an array of Integer objects to a primitive array (i.e.
static double[]	unboxFlatten(Double[][] src)	Flattens a two-dimensional array and unboxes.
static int[]	uniqueSorted(int[] src)	Gets the unique values from an array and sorts them.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

ArrayUtils

private ArrayUtils()

Method Details

deepCopy

public static int[][] deepCopy(int[][] src,
 int[][] dest)

Creates a deep copy of a 2D array. Assumes arrays are not jagged.

Parameters:

src - Source array to copy.

dest - Destination array of copy. If null, a new array will be initialized.

Returns:

A reference to dest if it was not null. In the case where dest is null, then a new array will be initialized and returned.

Throws:

IllegalArgumentException - If the two arrays are not the same shape.

copy2CNumber

public static CNumber[] copy2CNumber(int[] src,
 CNumber[] dest)

Converts array to an array of complex numbers.

Parameters:

src - Array to convert.

dest - Destination array. If the destination array is null, a new array will be created.

Returns:

A reference to the dest array.

Throws:

IllegalArgumentException - If source and destination arrays do not have the same length.

copy2CNumber

public static CNumber[] copy2CNumber(double[] src,
 CNumber[] dest)

Converts array to an array of complex numbers.

Parameters:

src - Array to convert.

dest - Destination array. If the destination array is null, a new array will be created.

Returns:

A reference to the dest array.

Throws:

IllegalArgumentException - If source and destination arrays do not have the same length.

copy2CNumber

public static CNumber[] copy2CNumber(Integer[] src,
 CNumber[] dest)

Converts array to an array of complex numbers.

Parameters:

src - Array to convert.

dest - Destination array. If the destination array is null, a new array will be created.

Returns:

A reference to the dest array.

Throws:

IllegalArgumentException - If source and destination arrays do not have the same length.

copy2CNumber

public static CNumber[] copy2CNumber(Double[] src,
 CNumber[] dest)

Converts array to an array of complex numbers.

Parameters:

src - Array to convert.

dest - Destination array. If the destination array is null, a new array will be created.

Returns:

A reference to the dest array.

Throws:

IllegalArgumentException - If source and destination arrays do not have the same length.

copy2CNumber

public static CNumber[] copy2CNumber(String[] src,
 CNumber[] dest)

Converts array to an array of complex numbers.

Parameters:

src - Array to convert.

dest - Destination array. If the destination array is null, a new array will be created.

Returns:

A reference to the dest array.

Throws:

IllegalArgumentException - If source and destination arrays do not have the same length.

arraycopy

public static void arraycopy(double[] src,
 int srcPos,
 CNumber[] dest,
 int destPos,
 int length)

Performs an array copy similar to System.arraycopy(Object, int, Object, int, int) but creates a deep copy of each element in the source array.

Parameters:

src - The source array.

srcPos - The starting position from which to copy elements of the source array.

dest - The destination array for the copy.

destPos - Starting index to place copied elements in the destination array.

length - The number of array elements to be copied.

Throws:

ArrayIndexOutOfBoundsException - If the destPos parameter plus the length parameter exceeds the length of the source array length or the destination array length.

fillZeros

public static void fillZeros(CNumber[][] dest)

Fills an array of complex numbers with zeros.

Parameters:

dest - Array to fill with zeros.

stridedFillZeros

public static void stridedFillZeros(double[] dest,
 int start,
 int stride)

Fills an array with zeros separated by the given stride.

If stride=3, start=1, and dest={1, 2, 3, 4, 5, 6, 7, 8, 9} then the result will be {1, 0, 3, 4, 0, 6, 7, 0, 9}.

Parameters:

dest - Array to fill with strided zeros.

start - Staring point in array to apply strided zero fill.

stride - Number of elements between each value to set to zero within the destination array.

Throws:

IllegalArgumentException - If stride is less than 1.

IllegalArgumentException - If start is less than 0.

stridedFillZeros

public static void stridedFillZeros(CNumber[] dest,
 int start,
 int stride)

Fills an array with zeros separated by the given stride.

If stride=3, start=1, and dest={1, 2, 3, 4, 5, 6, 7, 8, 9} then the result will be {1, 0, 3, 4, 0, 6, 7, 0, 9}.

Parameters:

dest - Array to fill with strided zeros.

start - Staring point in array to apply strided zero fill.

stride - Number of elements between each value to set to zero within the destination array.

Throws:

IllegalArgumentException - If stride is less than 1.

IllegalArgumentException - If start is less than 0.

stridedFillZeros

public static void stridedFillZeros(CNumber[] dest,
 int start,
 int length,
 int stride)

Fills an array with a range of zeros, each separated by the given stride. Specifically, the destination array will be filled with several sequential ranges of zeros of specified length. Each range of zeros will be separated by the stride.

If stride=2, length=3, start=1, and dest={1, 2, 3, 4, 5, 6, 7, 8, 9} then the result will be {1, 0, 0, 0, 5, 0, 0, 0, 9}.

Parameters:

dest - Array to fill with strided zeros.

start - Starting point to apply strided zero fill.

length - Number of sequential zeros to fill per stride.

stride - Number of elements between each value to set to zero within the destination array.

Throws:

IllegalArgumentException - If stride or length is less than one.

IllegalArgumentException - If start is less than zero.

stridedFillZeros

public static void stridedFillZeros(double[] dest,
 int start,
 int length,
 int stride)

Fills an array with a range of zeros, each separated by the given stride. Specifically, the destination array will be filled with several sequential ranges of zeros of specified length. Each range of zeros will be separated by the stride.

If stride=2, length=3, start=1, and dest={1, 2, 3, 4, 5, 6, 7, 8, 9} then the result will be {1, 0, 0, 0, 5, 0, 0, 0, 9}.

Parameters:

dest - Array to fill with strided zeros.

start - Starting point to apply strided zero fill.

length - Number of sequential zeros to fill per stride.

stride - Number of elements between each value to set to zero within the destination array.

Throws:

IllegalArgumentException - If stride or length is less than one.

IllegalArgumentException - If start is less than zero.

fill

public static void fill(CNumber[] dest,
 double fillValue)

Fills an array with specified value.

Parameters:

dest - Array to fill.

fillValue - Value to fill array with.

fill

public static void fill(CNumber[][] dest,
 CNumber fillValue)

Fills an array with specified value.

Parameters:

dest - Array to fill.

fillValue - Value to fill array with.

fill

public static void fill(CNumber[] dest,
 double fillValue,
 int from,
 int to)

Fills range of an array with specified value.

Parameters:

dest - Array to fill.

fillValue - Value to fill array with.

from - Staring index of range (inclusive).

to - Ending index of range (exclusive).

fill

public static void fill(CNumber[] dest,
 int start,
 int end,
 CNumber fillValue)

Fills an array with specified value. Similar to Arrays.fill(Object[], Object) but creates deep copy of the fill value for each position.

Parameters:

dest - Array to fill.

start - Starting index of range to fill (Inclusive).

end - Ending index of range to fill (Exclusive).

fillValue - Value to fill array with. Each index of the dest array will be filled with a deep copy of this value.

Throws:

ArrayIndexOutOfBoundsException - If start or end is not within the destination array.

fill

public static void fill(double[][] dest,
 double fillValue)

Fills an array with the specified value;

Parameters:

dest - Array to fill.

fillValue - Value to fill array with.

toArrayList

public static ArrayList<Double> toArrayList(double[] src)

Converts an array of doubles to an array list.

Parameters:

src - Array to convert.

Returns:

An equivalent array list.

toArrayList

public static ArrayList<CNumber> toArrayList(CNumber[] src)

Converts an array of complex numbers to an array list.

Parameters:

src - Array to convert.

Returns:

An equivalent array list.

toComplexArrayList

public static ArrayList<CNumber> toComplexArrayList(double[] src)

Converts an array of doubles to a complex array list.

Parameters:

src - Array to convert.

Returns:

An equivalent complex array list.

toArrayList

public static ArrayList<Integer> toArrayList(int[] src)

Converts an array of doubles to an array list.

Parameters:

src - Array to convert.

Returns:

An equivalent array list.

fromDoubleList

public static double[] fromDoubleList(List<Double> src)

Converts a list of Doubles objects to a primitive array.

Parameters:

src - Source list to convert.

Returns:

An array containing the same values as the src list.

fromIntegerList

public static int[] fromIntegerList(List<Integer> src)

Converts a list of Integer objects to a primitive array.

Parameters:

src - Source list to convert.

Returns:

An array containing the same values as the src list.

fromIntegerList

public static int[] fromIntegerList(List<Integer> src,
 int[] dest)

Converts a list of Integer objects to a primitive array.

Parameters:

src - Source list to convert.

dest - Destination array to store values from src in (modified). Must be at least as large as src.

Returns:

A reference to the dest array.

fromList

public static <T> T[] fromList(List<T> src,
 T[] dest)

Converts a list to an array.

Parameters:

src - Source list to convert.

dest - Destination array to store values from src in (modified). Must be at least as large as src.

Returns:

A reference to the dest array.

Throws:

IllegalArgumentException - If the dest array is not large enough to store all entries of src list.

swap

public static void swap(int[] arr,
 int i,
 int j)

Swaps to elements in an array. This is done in place.

Parameters:

arr - Array to swap elements in. This array is modified.

i - Index of first value to swap.

j - Index of second value to swap.

Throws:

IndexOutOfBoundsException - If i or j are out of the bounds of arr.

swap

public static void swap(int[] src,
 int[] indices)

Swaps elements in an array according to a specified permutation.

Parameters:

src - Array to swap elements within.

indices - Array containing indices of the permutation. If the src array has length N, then the array must be a permutation of {0, 1, 2, ..., N-1}.

Throws:

IllegalArgumentException - If indices is not a permutation of {0, 1, 2, ..., N-1}.

swapUnsafe

public static void swapUnsafe(int[] src,
 int[] indices)

Swaps elements in an array according to a specified permutation. This method should be used with extreem caution as unlike swap(int[], int[]), this method does not verify that indices is a permutation.

Parameters:

src - Array to swap elements within.

indices - Array containing indices of the permutation. If the src array has length N, then the array must be a permutation of {0, 1, 2, ..., N-1}.

swap

public static void swap(double[] arr,
 int i,
 int j)

Swaps to elements in an array. This is done in place.

Parameters:

arr - Array to swap elements in. This array is modified.

i - Index of first value to swap.

j - Index of second value to swap.

Throws:

IndexOutOfBoundsException - If i or j are out of the bounds of arr.

swap

public static void swap(Object[] arr,
 int i,
 int j)

Swaps to elements in an array. This is done in place.

Parameters:

arr - Array to swap elements in. This array is modified.

i - Index of first value to swap.

j - Index of second value to swap.

Throws:

IndexOutOfBoundsException - If i or j are out of the bounds of arr.

range

public static double[] range(int start,
 int end)

Gets an array filled with integers from start (inclusive) to end (exclusive)

Parameters:

start - Staring value (inclusive).

end - Stopping value (exclusive).

Returns:

An array containing the integer range [start, end).

intRange

public static int[] intRange(int start,
 int end)

Gets an array filled with integers from start (inclusive) to end (exclusive)

Parameters:

start - Staring value (inclusive).

end - Stopping value (exclusive).

Returns:

An array containing the integer range [start, end).

intRange

public static int[] intRange(int start,
 int end,
 int stride)

Gets an array filled with integers from start (inclusive) to end (exclusive) where each int is repeated stride times.

Parameters:

start - Staring value (inclusive).

end - Stopping value (exclusive).

stride - Number of times to repeat each integer.

Returns:

An array containing the integer range [start, end) and each integer is repeated stride times.

Throws:

NegativeArraySizeException - If stride is negative.

IllegalArgumentException - If start is not in [0, end)

equals

public static boolean equals(double[] src1,
 CNumber[] src2)

Checks if a double array is numerically equal to a complex number array.

Parameters:

src1 - Double array.

src2 - Complex number array.

Returns:

True if all entries in src2 have zero imaginary component and real component equal to the corresponding entry in src1. Otherwise, returns false.

notContains

public static boolean notContains(int[] src,
 int key)

Checks if a key is in an array.

Parameters:

src - Source array. Must be sorted, if not, call Arrays.sort(double[]) first. Otherwise, the behavior of this method is undefined.

key - Values to check if they are in the source array.

Returns:

A boolean describing if the specified key is in the array or not.

contains

public static boolean[] contains(double[] src,
 double... keys)

Checks if a set of keys are in an array.

Parameters:

src - Source array. Must be sorted, if not, call Arrays.sort(double[]) first. Otherwise, the behavior of this method is undefined.

keys - Values to check if they are in the source array.

Returns:

A boolean array with the same length as keys describing if the associated keys are in the array.

contains

public static boolean[] contains(int[] src,
 int... keys)

Checks if a set of keys is in an array.

Parameters:

src - Source array. Must be sorted, if not, call Arrays.sort(int[]) first. Otherwise, the behavior of this method is undefined.

keys - Values to check if they are in the source array.

Returns:

A boolean array with the same length as keys describing if the associated keys are in the array.

contains

public static boolean contains(int[] arr,
 int key)

Checks if an array contains a specified value. This method assumes that the array is sorted as it uses the binary search algorithm. If the array is not sorted, use Arrays.sort(int[]) first.

Parameters:

arr - Array of interest.

key - Value to check for in the arr array.

Returns:

True if the key value is found in the array. False otherwise.

See Also:

• Arrays.sort(int[])

contains

public static boolean contains(double[] arr,
 double key)

Checks if an array contains a specified value. This method assumes that the array is sorted as it uses the binary search algorithm. If the array is not sorted, use Arrays.sort(int[]) first.

Parameters:

arr - Array of interest.

key - Value to check for in the arr array.

Returns:

True if the key value is found in the array. False otherwise.

See Also:

• Arrays.sort(int[])

flatten

public static int[] flatten(int[][] src)

Flattens a two-dimensional array.

Parameters:

src - Array to flatten.

Returns:

The flattened array.

flatten

public static double[] flatten(double[][] src)

Flattens a two-dimensional array.

Parameters:

src - Array to flatten.

Returns:

The flattened array.

unboxFlatten

public static double[] unboxFlatten(Double[][] src)

Flattens a two-dimensional array and unboxes.

Parameters:

src - Array to flatten and unbox.

Returns:

The flattened array.

flatten

public static CNumber[] flatten(CNumber[][] src)

Flattens a two-dimensional array.

Parameters:

src - Array to flatten.

Returns:

The flattened array.

join

public static double[] join(double[] src1,
 double[] src2)

Joins two arrays together.

Parameters:

src1 - First array to join.

src2 - Second array to join.

Returns:

A single array of length src1.length + src2.length containing the elements of src1 followed by the elements of src2.

join

public static int[] join(int[] src1,
 int[] src2)

Joins two arrays together.

Parameters:

src1 - First array to join.

src2 - Second array to join.

Returns:

A single array of length src1.length + src2.length containing the elements of src1 followed by the elements of src2.

notInAxes

public static int[] notInAxes(int[] srcAxes,
 int dim)

Given a list of integers, srcAxes, which is a subset of {0, 1, 2, ...., dim-1} in no particular order, compute the integers which are in {0, 1, 2, ...., dim-1} but not in srcAxes.

Parameters:

srcAxes - Source axes which contains a subset of {0, 1, 2, ...., dim-1} in no particular order.

dim - Dimension of space which contains the axes of interest.

Returns:

An array containing the set subtraction {0, 1, 2, ...., dim-1} - srcAxes.

shift

public static int[] shift(int shift,
 int[] indices)

Shifts all indices in an array by a specified amount.

Parameters:

shift - Amount to shift indices by.

indices - Array of indices to shift.

Returns:

A reference to indices.

See Also:

• shiftRange(int, int[], int, int)

shiftRange

public static int[] shiftRange(int shift,
 int[] indices,
 int start,
 int stop)

Shifts a range of indices in an array by a specified amount.

Parameters:

shift - Amount to shift indices by.

indices - Array of indices to shift.

start - Starting index of range to shift (inclusive).

stop - Stopping index of range to shift (exclusive).

Returns:

A reference to indices.

Throws:

ArrayIndexOutOfBoundsException - If start or stop is not within the bounds of the indices array.

See Also:

• shift(int, int[])

uniqueSorted

public static int[] uniqueSorted(int[] src)

Gets the unique values from an array and sorts them.

Parameters:

src - The array to get unique values from.

Returns:

A sorted array containing all unique values in the src array.

indexOf

public static int indexOf(int[] arr,
 int key)

Finds the fist index of the specified key within an array. If the element does not exist, then -1 is returned.

Parameters:

arr - Array of interest.

key - Key value to search for.

Returns:

Returns the first index of the value key within the arr array. If the key does not occur in the array, -1 will be returned.

unbox

public static double[] unbox(Double[] arr)

Converts an array of Double objects to a primitive array (i.e. unboxing).

Parameters:

arr - Array to convert.

Returns:

A primitive array equivalent to arr.

unbox

public static int[] unbox(Integer[] arr)

Converts an array of Integer objects to a primitive array (i.e. unboxing).

Parameters:

arr - Array to convert.

Returns:

A primitive array equivalent to arr.

boxed

public static Double[] boxed(double[] src)

Converts a primitive array to an array of equivalent boxed type.

Parameters:

src - The source primitive array to box.

Returns:

A boxed array equivalent to the src primitive array.

boxed

public static Integer[] boxed(int[] src)

Converts a primitive array to an array of equivalent boxed type.

Parameters:

src - The source primitive array to box.

Returns:

A boxed array equivalent to the src primitive array.

numUnique

public static int numUnique(double[] arr)

Counts the number of unique elements in an array.

Parameters:

arr - Array to count unique elements in.

Returns:

The number of unique elements in arr.

numUnique

public static int numUnique(int[] arr)

Counts the number of unique elements in an array.

Parameters:

arr - Array to count unique elements in.

Returns:

The number of unique elements in arr.

createUniqueMapping

public static HashMap<Integer,Integer> createUniqueMapping(int[] arr)

Creates a mapping of unique values in {code arr} to integers such that each unique value is mapped to a unique integer and those integers range from 0 to numUnique(arr) - 1.

Parameters:

arr - Array to create a mapping for.

Returns:

A mapping of unique values in {code arr} to integers such that each unique value is mapped to a unique integer and those integers range from 0 to numUnique(arr) - 1.

findFirstLast

public static int[] findFirstLast(int[] src,
 int key)

Finds the first and last index of a specified key within a sorted array.

Parameters:

src - The source array to search within. This array is assumed ot be sorted. If the array is not sorted, call Arrays.sort(src) before this method. If this is not done, and an unsorted array is passed to this method, the results are undefined.

key - The key value to find the first and last index of within the src array.

Returns:

An array of length 2 containing the first (inclusive) and last (exclusive) index of the key within the src array. If the key value does not exist in the array, then both first and last index will be (-insertion_point - 1) where insertion_point is defined as the index the key would be inserted into the sorted array.

repeat

public static int[] repeat(int numTimes,
 int[] src)

Repeats an array a specified number of times.

Parameters:

numTimes - Number of times to repeat the array.

src - The source array to repeat.

Returns:

The src array repeated numTimes times.

filledArray

public static int[] filledArray(int size,
 int value)

Constructs an array filled with a specific value.

Parameters:

size - Size of the array.

value - Value to set each index of the array.

Returns:

An array of specified size filled with the specified value.

Throws:

NegativeArraySizeException - If is negative.

asDouble

public static double[] asDouble(int[] src,
 double[] dest)

Converts an array of ints to an array of doubles.

Parameters:

src - Source array to convert.

dest - Destination array to store double values equivalent to the values in the src array. If null, a new double array with the same size as src will be created.

Returns:

A reference to the dest array.

asDouble

public static double[] asDouble(Integer[] src,
 double[] dest)

Converts an array of Integers to an array of doubles.

Parameters:

src - Source array to convert.

dest - Destination array to store double values equivalent to the values in the src array. If null, a new double array with the same size as src will be created.

Returns:

A reference to the dest array.

splice

public static CNumber[] splice(CNumber[] arr1,
 CNumber[] arr2,
 int spliceIdx)

Splices an array into another array at the specified index.

Parameters:

arr1 - First array.

arr2 - Array to splice into arr1.

spliceIdx - The index within arr1 to splice arr2 into.

Returns:

The result of splicing arr2 into arr1 at the index spliceIdx.

splice

public static CNumber[] splice(CNumber[] arr1,
 double[] arr2,
 int spliceIdx)

Splices an array into another array at the specified index.

Parameters:

arr1 - First array.

arr2 - Array to splice into arr1.

spliceIdx - The index within arr1 to splice arr2 into.

Returns:

The result of splicing arr2 into arr1 at the index spliceIdx.

splice

public static CNumber[] splice(double[] arr1,
 CNumber[] arr2,
 int spliceIdx)

Splices an array into another array at the specified index.

Parameters:

arr1 - First array.

arr2 - Array to splice into arr1.

spliceIdx - The index within arr1 to splice arr2 into.

Returns:

The result of splicing arr2 into arr1 at the index spliceIdx.

splice

public static double[] splice(double[] arr1,
 double[] arr2,
 int spliceIdx)

Splices an array into another array at the specified index.

Parameters:

arr1 - First array.

arr2 - Array to splice into arr1.

spliceIdx - The index within arr1 to splice arr2 into.

Returns:

The result of splicing arr2 into arr1 at the index spliceIdx.

splice

public static int[] splice(int[] arr1,
 int[] arr2,
 int spliceIdx)

Splices an array into another array at the specified index.

Parameters:

arr1 - First array.

arr2 - Array to splice into arr1.

spliceIdx - The index within arr1 to splice arr2 into.

Returns:

The result of splicing arr2 into arr1 at the index spliceIdx.

splice

public static double[] splice(List<Double> list,
 double[] arr,
 int spliceIdx)

Splices an array into a list at the specified index. The list is implicitly converted to an array.

Parameters:

list - List to splice into.

arr - Array to splice into list.

spliceIdx - The index within list to splice arr into.

Returns:

The result of splicing arr into list at the index spliceIdx.

spliceDouble

public static CNumber[] spliceDouble(List<CNumber> list,
 double[] arr,
 int spliceIdx)

Splices an array into a list at the specified index. The list is implicitly converted to an array.

Parameters:

list - List to splice into.

arr - Array to splice into list.

spliceIdx - The index within list to splice arr into.

Returns:

The result of splicing arr into list at the index spliceIdx.

splice

public static CNumber[] splice(List<CNumber> list,
 CNumber[] arr,
 int spliceIdx)

Splices an array into a list at the specified index. The list is implicitly converted to an array.

Parameters:

list - List to splice into.

arr - Array to splice into list.

spliceIdx - The index within list to splice arr into.

Returns:

The result of splicing arr into list at the index spliceIdx.

splice

public static int[] splice(List<Integer> list,
 int[] arr,
 int spliceIdx)

Splices an array into a list at the specified index. The list is implicitly converted to an array.

Parameters:

list - List to splice into.

arr - Array to splice into list.

spliceIdx - The index within list to splice arr into.

Returns:

The result of splicing arr into list at the index spliceIdx.

applyTransform

public static double[] applyTransform(double[] src,
 UnaryOperator<Double> opp)

Applies a transform to an array. This is done in place.

Parameters:

src - Array to apply transform to. Modified.

opp - Operation to use to transform the array.

Returns:

A reference to the src array.

applyTransform

public static <T> T[] applyTransform(T[] src,
 UnaryOperator<T> opp)

Applies a transform to an array. This is done in place.

Parameters:

src - Array to apply transform to. Modified.

opp - Operation to use to transform the array.

Returns:

A reference to the src array.

applyTransform

public static CNumber[] applyTransform(double[] src,
 Function<Double,CNumber> opp)

Applies a transform to an array. Note, unlike applyTransform(double[], UnaryOperator) and applyTransform(Object[], UnaryOperator), this method does not work in place.

Parameters:

src - Array to apply transform to.

opp - Operation to use to transform the array.

Returns:

A new array containing the result of the transformation.

See Also:

• applyTransform(Object[], UnaryOperator)
• applyTransform(double[], UnaryOperator)

applyTransform

public static double[] applyTransform(CNumber[] src,
 Function<CNumber,Double> opp)

Applies a transform to an array. Note, unlike applyTransform(double[], UnaryOperator) and applyTransform(Object[], UnaryOperator), this method does not work in place.

Parameters:

src - Array to apply transform to.

opp - Operation to use to transform the array.

Returns:

A new array containing the result of the transformation.

See Also:

• applyTransform(Object[], UnaryOperator)
• applyTransform(double[], UnaryOperator)