it.unimi.dsi.fastutil.bytes
Class ByteBigArrays

java.lang.Object
  extended by it.unimi.dsi.fastutil.bytes.ByteBigArrays

public class ByteBigArrays
extends java.lang.Object

A class providing static methods and objects that do useful things with big arrays.

In particular, the ensureCapacity(), grow(), trim() and setLength() methods allow to handle big arrays much like array lists.

Note that BinIO and TextIO contain several methods that make it possible to load and save big arrays of primitive types as sequences of elements in DataInput format (i.e., not as objects) or as sequences of lines of text.

See Also:
BigArrays

Field Summary
static byte[][] EMPTY_BIG_ARRAY
          A static, final, empty big array.
static Hash.Strategy HASH_STRATEGY
          A type-specific content-based hash strategy for big arrays.
 
Method Summary
static void add(byte[][] array, long index, byte incr)
          Adds the specified increment the element of the given big array of specified index.
static long binarySearch(byte[][] a, byte key)
          Searches a big array for the specified value using the binary search algorithm.
static long binarySearch(byte[][] a, byte key, ByteComparator c)
          Searches a big array for the specified value using the binary search algorithm and a specified comparator.
static long binarySearch(byte[][] a, long from, long to, byte key)
          Searches a range of the specified big array for the specified value using the binary search algorithm.
static long binarySearch(byte[][] a, long from, long to, byte key, ByteComparator c)
          Searches a range of the specified big array for the specified value using the binary search algorithm and a specified comparator.
static byte[][] copy(byte[][] array)
          Returns a copy of a big array.
static void copy(byte[][] srcArray, long srcPos, byte[][] destArray, long destPos, long length)
          Copies a big array from the specified source big array, beginning at the specified position, to the specified position of the destination big array.
static byte[][] copy(byte[][] array, long offset, long length)
          Returns a copy of a portion of a big array.
static void copyFromBig(byte[][] srcArray, long srcPos, byte[] destArray, int destPos, int length)
          Copies a big array from the specified source big array, beginning at the specified position, to the specified position of the destination array.
static void copyToBig(byte[] srcArray, int srcPos, byte[][] destArray, long destPos, long length)
          Copies an array from the specified source array, beginning at the specified position, to the specified position of the destination big array.
static void decr(byte[][] array, long index)
          Decrements the element of the given big array of specified index.
static byte[][] ensureCapacity(byte[][] array, long length)
          Ensures that a big array can contain the given number of entries.
static byte[][] ensureCapacity(byte[][] array, long length, long preserve)
          Ensures that a big array can contain the given number of entries, preserving just a part of the big array.
static void ensureFromTo(byte[][] a, long from, long to)
          Ensures that a range given by its first (inclusive) and last (exclusive) elements fits a big array.
static void ensureOffsetLength(byte[][] a, long offset, long length)
          Ensures that a range given by an offset and a length fits a big array.
static boolean equals(byte[][] a1, byte[][] a2)
          Returns true if the two big arrays are elementwise equal.
static void fill(byte[][] array, byte value)
          Fills the given big array with the given value.
static void fill(byte[][] array, long from, long to, byte value)
          Fills a portion of the given big array with the given value.
static byte get(byte[][] array, long index)
          Returns the element of the given big array of specified index.
static byte[][] grow(byte[][] array, long length)
          Grows the given big array to the maximum between the given length and the current length multiplied by two, provided that the given length is larger than the current length.
static byte[][] grow(byte[][] array, long length, long preserve)
          Grows the given big array to the maximum between the given length and the current length multiplied by two, provided that the given length is larger than the current length, preserving just a part of the big array.
static void incr(byte[][] array, long index)
          Increments the element of the given big array of specified index.
static long length(byte[][] array)
          Returns the length of the given big array.
static void mul(byte[][] array, long index, byte factor)
          Multiplies by the specified factor the element of the given big array of specified index.
static byte[][] newBigArray(long length)
          Creates a new big array.
static void quickSort(byte[][] x)
          Sorts the specified big array according to the natural ascending order using quicksort.
static void quickSort(byte[][] x, ByteComparator comp)
          Sorts the specified big array according to the order induced by the specified comparator using quicksort.
static void quickSort(byte[][] x, long from, long to)
          Sorts the specified range of elements according to the natural ascending order using quicksort.
static void quickSort(byte[][] x, long from, long to, ByteComparator comp)
          Sorts the specified range of elements according to the order induced by the specified comparator using quicksort.
static void radixSort(byte[][] a)
          Sorts the specified big array using radix sort.
static void radixSort(byte[][] a, byte[][] b)
          Sorts the specified pair of big arrays lexicographically using radix sort.
static void radixSort(byte[][] a, byte[][] b, long from, long to)
          Sorts the specified pair of big arrays lexicographically using radix sort.
static void radixSort(byte[][] a, long from, long to)
          Sorts the specified big array using radix sort.
static void set(byte[][] array, long index, byte value)
          Sets the element of the given big array of specified index.
static byte[][] setLength(byte[][] array, long length)
          Sets the length of the given big array.
static byte[][] shuffle(byte[][] a, long from, long to, java.util.Random random)
          Shuffles the specified big array fragment using the specified pseudorandom number generator.
static byte[][] shuffle(byte[][] a, java.util.Random random)
          Shuffles the specified big array using the specified pseudorandom number generator.
static void swap(byte[][] array, long first, long second)
          Swaps the element of the given big array of specified indices.
static java.lang.String toString(byte[][] a)
           
static byte[][] trim(byte[][] array, long length)
          Trims the given big array to the given length.
static byte[][] wrap(byte[] array)
          Turns a standard array into a big array.
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

EMPTY_BIG_ARRAY

public static final byte[][] EMPTY_BIG_ARRAY
A static, final, empty big array.


HASH_STRATEGY

public static final Hash.Strategy HASH_STRATEGY
A type-specific content-based hash strategy for big arrays.

This hash strategy may be used in custom hash collections whenever keys are big arrays, and they must be considered equal by content. This strategy will handle null correctly, and it is serializable.

Method Detail

get

public static byte get(byte[][] array,
                       long index)
Returns the element of the given big array of specified index.

Parameters:
array - a big array.
index - a position in the big array.
Returns:
the element of the big array at the specified position.

set

public static void set(byte[][] array,
                       long index,
                       byte value)
Sets the element of the given big array of specified index.

Parameters:
array - a big array.
index - a position in the big array.

swap

public static void swap(byte[][] array,
                        long first,
                        long second)
Swaps the element of the given big array of specified indices.

Parameters:
array - a big array.
first - a position in the big array.
second - a position in the big array.

add

public static void add(byte[][] array,
                       long index,
                       byte incr)
Adds the specified increment the element of the given big array of specified index.

Parameters:
array - a big array.
index - a position in the big array.
incr - the increment

mul

public static void mul(byte[][] array,
                       long index,
                       byte factor)
Multiplies by the specified factor the element of the given big array of specified index.

Parameters:
array - a big array.
index - a position in the big array.
factor - the factor

incr

public static void incr(byte[][] array,
                        long index)
Increments the element of the given big array of specified index.

Parameters:
array - a big array.
index - a position in the big array.

decr

public static void decr(byte[][] array,
                        long index)
Decrements the element of the given big array of specified index.

Parameters:
array - a big array.
index - a position in the big array.

length

public static long length(byte[][] array)
Returns the length of the given big array.

Parameters:
array - a big array.
Returns:
the length of the given big array.

copy

public static void copy(byte[][] srcArray,
                        long srcPos,
                        byte[][] destArray,
                        long destPos,
                        long length)
Copies a big array from the specified source big array, beginning at the specified position, to the specified position of the destination big array. Handles correctly overlapping regions of the same big array.

Parameters:
srcArray - the source big array.
srcPos - the starting position in the source big array.
destArray - the destination big array.
destPos - the starting position in the destination data.
length - the number of elements to be copied.

copyFromBig

public static void copyFromBig(byte[][] srcArray,
                               long srcPos,
                               byte[] destArray,
                               int destPos,
                               int length)
Copies a big array from the specified source big array, beginning at the specified position, to the specified position of the destination array.

Parameters:
srcArray - the source big array.
srcPos - the starting position in the source big array.
destArray - the destination array.
destPos - the starting position in the destination data.
length - the number of elements to be copied.

copyToBig

public static void copyToBig(byte[] srcArray,
                             int srcPos,
                             byte[][] destArray,
                             long destPos,
                             long length)
Copies an array from the specified source array, beginning at the specified position, to the specified position of the destination big array.

Parameters:
srcArray - the source array.
srcPos - the starting position in the source array.
destArray - the destination big array.
destPos - the starting position in the destination data.
length - the number of elements to be copied.

newBigArray

public static byte[][] newBigArray(long length)
Creates a new big array.

Parameters:
length - the length of the new big array.
Returns:
a new big array of given length.

wrap

public static byte[][] wrap(byte[] array)
Turns a standard array into a big array.

Note that the returned big array might contain as a segment the original array.

Parameters:
array - an array.
Returns:
a new big array with the same length and content of array.

ensureCapacity

public static byte[][] ensureCapacity(byte[][] array,
                                      long length)
Ensures that a big array can contain the given number of entries.

If you cannot foresee whether this big array will need again to be enlarged, you should probably use grow() instead.

Warning: the returned array might use part of the segments of the original array, which must be considered read-only after calling this method.

Parameters:
array - a big array.
length - the new minimum length for this big array.
Returns:
array, if it contains length entries or more; otherwise, a big array with length entries whose first length(array) entries are the same as those of array.

ensureCapacity

public static byte[][] ensureCapacity(byte[][] array,
                                      long length,
                                      long preserve)
Ensures that a big array can contain the given number of entries, preserving just a part of the big array.

Warning: the returned array might use part of the segments of the original array, which must be considered read-only after calling this method.

Parameters:
array - a big array.
length - the new minimum length for this big array.
preserve - the number of elements of the big array that must be preserved in case a new allocation is necessary.
Returns:
array, if it can contain length entries or more; otherwise, a big array with length entries whose first preserve entries are the same as those of array.

grow

public static byte[][] grow(byte[][] array,
                            long length)
Grows the given big array to the maximum between the given length and the current length multiplied by two, provided that the given length is larger than the current length.

If you want complete control on the big array growth, you should probably use ensureCapacity() instead.

Warning: the returned array might use part of the segments of the original array, which must be considered read-only after calling this method.

Parameters:
array - a big array.
length - the new minimum length for this big array.
Returns:
array, if it can contain length entries; otherwise, a big array with max(length,length(array)/φ) entries whose first length(array) entries are the same as those of array.

grow

public static byte[][] grow(byte[][] array,
                            long length,
                            long preserve)
Grows the given big array to the maximum between the given length and the current length multiplied by two, provided that the given length is larger than the current length, preserving just a part of the big array.

If you want complete control on the big array growth, you should probably use ensureCapacity() instead.

Warning: the returned array might use part of the segments of the original array, which must be considered read-only after calling this method.

Parameters:
array - a big array.
length - the new minimum length for this big array.
preserve - the number of elements of the big array that must be preserved in case a new allocation is necessary.
Returns:
array, if it can contain length entries; otherwise, a big array with max(length,length(array)/φ) entries whose first preserve entries are the same as those of array.

trim

public static byte[][] trim(byte[][] array,
                            long length)
Trims the given big array to the given length.

Warning: the returned array might use part of the segments of the original array, which must be considered read-only after calling this method.

Parameters:
array - a big array.
length - the new maximum length for the big array.
Returns:
array, if it contains length entries or less; otherwise, a big array with length entries whose entries are the same as the first length entries of array.

setLength

public static byte[][] setLength(byte[][] array,
                                 long length)
Sets the length of the given big array.

Warning: the returned array might use part of the segments of the original array, which must be considered read-only after calling this method.

Parameters:
array - a big array.
length - the new length for the big array.
Returns:
array, if it contains exactly length entries; otherwise, if it contains more than length entries, a big array with length entries whose entries are the same as the first length entries of array; otherwise, a big array with length entries whose first length(array) entries are the same as those of array.

copy

public static byte[][] copy(byte[][] array,
                            long offset,
                            long length)
Returns a copy of a portion of a big array.

Parameters:
array - a big array.
offset - the first element to copy.
length - the number of elements to copy.
Returns:
a new big array containing length elements of array starting at offset.

copy

public static byte[][] copy(byte[][] array)
Returns a copy of a big array.

Parameters:
array - a big array.
Returns:
a copy of array.

fill

public static void fill(byte[][] array,
                        byte value)
Fills the given big array with the given value.

This method uses a backward loop. It is significantly faster than the corresponding method in Arrays.

Parameters:
array - a big array.
value - the new value for all elements of the big array.

fill

public static void fill(byte[][] array,
                        long from,
                        long to,
                        byte value)
Fills a portion of the given big array with the given value.

If possible (i.e., from is 0) this method uses a backward loop. In this case, it is significantly faster than the corresponding method in Arrays.

Parameters:
array - a big array.
from - the starting index of the portion to fill.
to - the end index of the portion to fill.
value - the new value for all elements of the specified portion of the big array.

equals

public static boolean equals(byte[][] a1,
                             byte[][] a2)
Returns true if the two big arrays are elementwise equal.

This method uses a backward loop. It is significantly faster than the corresponding method in Arrays.

Parameters:
a1 - a big array.
a2 - another big array.
Returns:
true if the two big arrays are of the same length, and their elements are equal.

toString

public static java.lang.String toString(byte[][] a)

ensureFromTo

public static void ensureFromTo(byte[][] a,
                                long from,
                                long to)
Ensures that a range given by its first (inclusive) and last (exclusive) elements fits a big array.

This method may be used whenever a big array range check is needed.

Parameters:
a - a big array.
from - a start index (inclusive).
to - an end index (inclusive).
Throws:
java.lang.IllegalArgumentException - if from is greater than to.
java.lang.ArrayIndexOutOfBoundsException - if from or to are greater than the big array length or negative.

ensureOffsetLength

public static void ensureOffsetLength(byte[][] a,
                                      long offset,
                                      long length)
Ensures that a range given by an offset and a length fits a big array.

This method may be used whenever a big array range check is needed.

Parameters:
a - a big array.
offset - a start index.
length - a length (the number of elements in the range).
Throws:
java.lang.IllegalArgumentException - if length is negative.
java.lang.ArrayIndexOutOfBoundsException - if offset is negative or offset+length is greater than the big array length.

quickSort

public static void quickSort(byte[][] x,
                             long from,
                             long to,
                             ByteComparator comp)
Sorts the specified range of elements according to the order induced by the specified comparator using quicksort.

The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11), pages 1249−1265, 1993.

Parameters:
x - the big array to be sorted.
from - the index of the first element (inclusive) to be sorted.
to - the index of the last element (exclusive) to be sorted.
comp - the comparator to determine the sorting order.

quickSort

public static void quickSort(byte[][] x,
                             ByteComparator comp)
Sorts the specified big array according to the order induced by the specified comparator using quicksort.

The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11), pages 1249−1265, 1993.

Parameters:
x - the big array to be sorted.
comp - the comparator to determine the sorting order.

quickSort

public static void quickSort(byte[][] x,
                             long from,
                             long to)
Sorts the specified range of elements according to the natural ascending order using quicksort.

The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11), pages 1249−1265, 1993.

Parameters:
x - the big array to be sorted.
from - the index of the first element (inclusive) to be sorted.
to - the index of the last element (exclusive) to be sorted.

quickSort

public static void quickSort(byte[][] x)
Sorts the specified big array according to the natural ascending order using quicksort.

The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11), pages 1249−1265, 1993.

Parameters:
x - the big array to be sorted.

binarySearch

public static long binarySearch(byte[][] a,
                                long from,
                                long to,
                                byte key)
Searches a range of the specified big array for the specified value using the binary search algorithm. The range must be sorted prior to making this call. If it is not sorted, the results are undefined. If the range contains multiple elements with the specified value, there is no guarantee which one will be found.

Parameters:
a - the big array to be searched.
from - the index of the first element (inclusive) to be searched.
to - the index of the last element (exclusive) to be searched.
key - the value to be searched for.
Returns:
index of the search key, if it is contained in the big array; otherwise, (-(insertion point) - 1). The insertion point is defined as the the point at which the value would be inserted into the big array: the index of the first element greater than the key, or the length of the big array, if all elements in the big array are less than the specified key. Note that this guarantees that the return value will be >= 0 if and only if the key is found.
See Also:
Arrays

binarySearch

public static long binarySearch(byte[][] a,
                                byte key)
Searches a big array for the specified value using the binary search algorithm. The range must be sorted prior to making this call. If it is not sorted, the results are undefined. If the range contains multiple elements with the specified value, there is no guarantee which one will be found.

Parameters:
a - the big array to be searched.
key - the value to be searched for.
Returns:
index of the search key, if it is contained in the big array; otherwise, (-(insertion point) - 1). The insertion point is defined as the the point at which the value would be inserted into the big array: the index of the first element greater than the key, or the length of the big array, if all elements in the big array are less than the specified key. Note that this guarantees that the return value will be >= 0 if and only if the key is found.
See Also:
Arrays

binarySearch

public static long binarySearch(byte[][] a,
                                long from,
                                long to,
                                byte key,
                                ByteComparator c)
Searches a range of the specified big array for the specified value using the binary search algorithm and a specified comparator. The range must be sorted following the comparator prior to making this call. If it is not sorted, the results are undefined. If the range contains multiple elements with the specified value, there is no guarantee which one will be found.

Parameters:
a - the big array to be searched.
from - the index of the first element (inclusive) to be searched.
to - the index of the last element (exclusive) to be searched.
key - the value to be searched for.
c - a comparator.
Returns:
index of the search key, if it is contained in the big array; otherwise, (-(insertion point) - 1). The insertion point is defined as the the point at which the value would be inserted into the big array: the index of the first element greater than the key, or the length of the big array, if all elements in the big array are less than the specified key. Note that this guarantees that the return value will be >= 0 if and only if the key is found.
See Also:
Arrays

binarySearch

public static long binarySearch(byte[][] a,
                                byte key,
                                ByteComparator c)
Searches a big array for the specified value using the binary search algorithm and a specified comparator. The range must be sorted following the comparator prior to making this call. If it is not sorted, the results are undefined. If the range contains multiple elements with the specified value, there is no guarantee which one will be found.

Parameters:
a - the big array to be searched.
key - the value to be searched for.
c - a comparator.
Returns:
index of the search key, if it is contained in the big array; otherwise, (-(insertion point) - 1). The insertion point is defined as the the point at which the value would be inserted into the big array: the index of the first element greater than the key, or the length of the big array, if all elements in the big array are less than the specified key. Note that this guarantees that the return value will be >= 0 if and only if the key is found.
See Also:
Arrays

radixSort

public static void radixSort(byte[][] a)
Sorts the specified big array using radix sort.

The sorting algorithm is a tuned radix sort adapted from Peter M. McIlroy, Keith Bostic and M. Douglas McIlroy, “Engineering radix sort”, Computing Systems, 6(1), pages 5−27 (1993), and further improved using the digit-oracle idea described by Juha Kärkkäinen and Tommi Rantala in “Engineering radix sort for strings”, String Processing and Information Retrieval, 15th International Symposium, volume 5280 of Lecture Notes in Computer Science, pages 3−14, Springer (2008).

This implementation is significantly faster than quicksort already at small sizes (say, more than 10000 elements), but it can only sort in ascending order. It will allocate a support array of bytes with the same number of elements as the array to be sorted.

Parameters:
a - the big array to be sorted.

radixSort

public static void radixSort(byte[][] a,
                             long from,
                             long to)
Sorts the specified big array using radix sort.

The sorting algorithm is a tuned radix sort adapted from Peter M. McIlroy, Keith Bostic and M. Douglas McIlroy, “Engineering radix sort”, Computing Systems, 6(1), pages 5−27 (1993), and further improved using the digit-oracle idea described by Juha Kärkkäinen and Tommi Rantala in “Engineering radix sort for strings”, String Processing and Information Retrieval, 15th International Symposium, volume 5280 of Lecture Notes in Computer Science, pages 3−14, Springer (2008).

This implementation is significantly faster than quicksort already at small sizes (say, more than 10000 elements), but it can only sort in ascending order. It will allocate a support array of bytes with the same number of elements as the array to be sorted.

Parameters:
a - the big array to be sorted.
from - the index of the first element (inclusive) to be sorted.
to - the index of the last element (exclusive) to be sorted.

radixSort

public static void radixSort(byte[][] a,
                             byte[][] b)
Sorts the specified pair of big arrays lexicographically using radix sort.

The sorting algorithm is a tuned radix sort adapted from Peter M. McIlroy, Keith Bostic and M. Douglas McIlroy, “Engineering radix sort”, Computing Systems, 6(1), pages 5−27 (1993), and further improved using the digit-oracle idea described by Juha Kärkkäinen and Tommi Rantala in “Engineering radix sort for strings”, String Processing and Information Retrieval, 15th International Symposium, volume 5280 of Lecture Notes in Computer Science, pages 3−14, Springer (2008).

This method implements a lexicographical sorting of the arguments. Pairs of elements in the same position in the two provided arrays will be considered a single key, and permuted accordingly. In the end, either a[ i ] < a[ i + 1 ] or a[ i ] == a[ i + 1 ] and b[ i ] <= b[ i + 1 ].

This implementation is significantly faster than quicksort already at small sizes (say, more than 10000 elements), but it can only sort in ascending order. It will allocate a support array of bytes with the same number of elements as the arrays to be sorted.

Parameters:
a - the first big array to be sorted.
b - the second big array to be sorted.

radixSort

public static void radixSort(byte[][] a,
                             byte[][] b,
                             long from,
                             long to)
Sorts the specified pair of big arrays lexicographically using radix sort.

The sorting algorithm is a tuned radix sort adapted from Peter M. McIlroy, Keith Bostic and M. Douglas McIlroy, “Engineering radix sort”, Computing Systems, 6(1), pages 5−27 (1993), and further improved using the digit-oracle idea described by Juha Kärkkäinen and Tommi Rantala in “Engineering radix sort for strings”, String Processing and Information Retrieval, 15th International Symposium, volume 5280 of Lecture Notes in Computer Science, pages 3−14, Springer (2008).

This method implements a lexicographical sorting of the arguments. Pairs of elements in the same position in the two provided arrays will be considered a single key, and permuted accordingly. In the end, either a[ i ] < a[ i + 1 ] or a[ i ] == a[ i + 1 ] and b[ i ] <= b[ i + 1 ].

This implementation is significantly faster than quicksort already at small sizes (say, more than 10000 elements), but it can only sort in ascending order. It will allocate a support array of bytes with the same number of elements as the arrays to be sorted.

Parameters:
a - the first big array to be sorted.
b - the second big array to be sorted.
from - the index of the first element (inclusive) to be sorted.
to - the index of the last element (exclusive) to be sorted.

shuffle

public static byte[][] shuffle(byte[][] a,
                               long from,
                               long to,
                               java.util.Random random)
Shuffles the specified big array fragment using the specified pseudorandom number generator.

Parameters:
a - the big array to be shuffled.
from - the index of the first element (inclusive) to be shuffled.
to - the index of the last element (exclusive) to be shuffled.
random - a pseudorandom number generator (please use a XorShift* generator).
Returns:
a.

shuffle

public static byte[][] shuffle(byte[][] a,
                               java.util.Random random)
Shuffles the specified big array using the specified pseudorandom number generator.

Parameters:
a - the big array to be shuffled.
random - a pseudorandom number generator (please use a XorShift* generator).
Returns:
a.