org.openimaj.util.array

Class SparseIntArray

java.lang.Object

org.openimaj.util.array.SparseIntArray

All Implemented Interfaces:

Readable, ReadableASCII, ReadableBinary, ReadWriteable, Writeable, WriteableASCII, WriteableBinary, Concatenatable<SparseIntArray,SparseIntArray>

Direct Known Subclasses:

SparseBinSearchIntArray, SparseHashedIntArray

public abstract class SparseIntArray
extends Object
implements ReadWriteable, Concatenatable<SparseIntArray,SparseIntArray>

A sparse array of int values. Includes some elementary vector operations (add, subtract, scalar multiply, dot product).

Author:

Jonathon Hare (jsh2@ecs.soton.ac.uk)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SparseIntArray.DualEntry An entry representing the values in two parallel SparseIntArrays at the same index.
static class	SparseIntArray.Entry An entry in a SparseIntArray, consisting of an index and value.

Field Summary

Fields

Modifier and Type	Field and Description
protected static int	DEFAULT_CAPACITY
int	length The length of the array

Constructor Summary

Constructors

Constructor and Description
SparseIntArray()

Method Summary

Modifier and Type	Method and Description
SparseIntArray	add(SparseIntArray vector) Add the values in the given vector to a copy of this array and return the result
SparseIntArray	addInplace(SparseIntArray vector) Add the values in the given vector to this vector and return this
String	asciiHeader() Header for ascii input.
byte[]	binaryHeader() Header for binary input.
abstract void	compact() Compact the space being used by the array if possible.
SparseIntArray	concatenate(List<SparseIntArray> ins) Concatenate all the inputs with this, returning a new object that is the result of the concatenation.
SparseIntArray	concatenate(SparseIntArray... ins) Concatenate all the inputs with this, returning a new object that is the result of the concatenation.
static SparseIntArray	concatenateArrays(SparseIntArray... arrays) Concatenate multiple arrays into a single new array.
abstract SparseIntArray	copy() Deep copy the array.
float	density()
double	dotProduct(SparseIntArray vector) Compute the dot product with another vector
abstract Iterable<SparseIntArray.Entry>	entries() Provide an iterator over the non-zero values.
abstract int	get(int index) Get the value at the given index.
abstract int	increment(int index, int value) Increment the value at the given index.
abstract int[]	indices()
Iterable<SparseIntArray.DualEntry>	intersectEntries(SparseIntArray otherArray) Provide an iterator over the intersection of values present in both this array and another array.
abstract boolean	isUsed(int index) Check whether the given index is used (i.e.
int	length()
int	maxIndex()
int	maxValue()
int	minIndex()
int	minValue()
SparseIntArray	multiply(double value) Copy this vector and multiply its values by a scalar
SparseIntArray	multiplyInplace(double value) Multiply the values inplace by a scalar and return this
void	readASCII(Scanner in) Read internal state from in.
void	readBinary(DataInput in) Read internal state from in.
abstract SparseIntArray	reverse() Reverse the elements, returning this.
abstract int	set(int index, int value) Set the value at the given index.
void	setLength(int newLength) Set the length of the array.
int	size()
SparseIntArray	subtract(SparseIntArray vector) Subtract the values in the given vector from a copy of this vector and return the result
SparseIntArray	subtractInplace(SparseIntArray vector) Subtract the values in the given vector from this array and return this
int	sumValues() Compute the sum of values
int	sumValuesSquared() Compute the sum of values squared
int[]	toArray() Convert this sparse array to a dense array.
int[]	toArray(int[] array) Convert this sparse array to a dense array.
Iterable<SparseIntArray.DualEntry>	unionEntries(SparseIntArray otherArray) Provide an iterator over the union of values present in both this array and another array.
abstract int	used()
abstract int[]	values()
void	writeASCII(PrintWriter out) Write the content of this as ascii to out.
void	writeBinary(DataOutput out) Write the content of this as binary to out.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_CAPACITY

protected static final int DEFAULT_CAPACITY

See Also:

Constant Field Values

length

public int length

The length of the array

Constructor Detail

SparseIntArray

public SparseIntArray()

Method Detail

increment

public abstract int increment(int index,
                              int value)

Increment the value at the given index.

Parameters:

index - the index

value - the amount to increment by.

Returns:

the new value

indices

public abstract int[] indices()

Returns:

the indices of the non-zero valued entries of the array.

values

public abstract int[] values()

Returns:

the packed non-zero valued entries of the array.

entries

public abstract Iterable<SparseIntArray.Entry> entries()

Provide an iterator over the non-zero values.

Note: the SparseIntArray.Entry returned by the iterator is always the same object. In addition, the iterator cannot affect the value of anything in the array (i.e. changing anything in the SparseIntArray.Entry has no effect on the actual array).

Returns:

an iterator over the non-zero values.

unionEntries

public Iterable<SparseIntArray.DualEntry> unionEntries(SparseIntArray otherArray)

Provide an iterator over the union of values present in both this array and another array. Values where both arrays are zero are skipped.

Note: the SparseIntArray.DualEntry returned by the iterator is always the same object. In addition, the iterator cannot affect the value of anything in the array (i.e. changing anything in the SparseIntArray.DualEntry has no effect on the actual array).

Parameters:

otherArray - the second array

Returns:

an iterator over the non-zero values.

intersectEntries

public Iterable<SparseIntArray.DualEntry> intersectEntries(SparseIntArray otherArray)

Provide an iterator over the intersection of values present in both this array and another array. Values are only presented for the cases where both arrays are non-zero.

Note: the SparseIntArray.DualEntry returned by the iterator is always the same object. In addition, the iterator cannot affect the value of anything in the array (i.e. changing anything in the SparseIntArray.DualEntry has no effect on the actual array).

Parameters:

otherArray - the second array

Returns:

an iterator over the non-zero values.

get

public abstract int get(int index)

Get the value at the given index.

Parameters:

index - the index

Returns:

the value at the index.

isUsed

public abstract boolean isUsed(int index)

Check whether the given index is used (i.e. has a non-zero value)

Parameters:

index - the index

Returns:

true if not used; false otherwise.

set

public abstract int set(int index,
                        int value)

Set the value at the given index.

Parameters:

index - the index.

value - the value to set.

Returns:

the value

setLength

public void setLength(int newLength)

Set the length of the array. Arrays can only be extended with this method.

Parameters:

newLength - the new array length

Throws:

IllegalArgumentException - if the new length is shorter than the existing length.

size

public int size()

Returns:

the length of the array

length

public int length()

Returns:

the length of the array

used

public abstract int used()

Returns:

the number of non-zero entries in the array

density

public float density()

Returns:

the density of the array (number of used elements divided by array length)

compact

public abstract void compact()

Compact the space being used by the array if possible.

writeASCII

public void writeASCII(PrintWriter out)
                throws IOException

Description copied from interface: WriteableASCII

Write the content of this as ascii to out.

Specified by:

writeASCII in interface WriteableASCII

Parameters:

out - sink to write to

Throws:

IOException - an error writing to out

readASCII

public void readASCII(Scanner in)
               throws IOException

Description copied from interface: ReadableASCII

Read internal state from in.

Specified by:

readASCII in interface ReadableASCII

Parameters:

in - source to read from.

Throws:

IOException - an error reading input

asciiHeader

public String asciiHeader()

Description copied from interface: ReadableASCII

Header for ascii input. Will be automatically read by IOUtils when using readASCII().

Specified by:

asciiHeader in interface ReadableASCII

Specified by:

asciiHeader in interface WriteableASCII

Returns:

header

writeBinary

public void writeBinary(DataOutput out)
                 throws IOException

Description copied from interface: WriteableBinary

Write the content of this as binary to out.

Specified by:

writeBinary in interface WriteableBinary

Parameters:

out - sink to write to

Throws:

IOException - an error writing to out

readBinary

public void readBinary(DataInput in)
                throws IOException

Description copied from interface: ReadableBinary

Read internal state from in.

Specified by:

readBinary in interface ReadableBinary

Parameters:

in - source to read from.

Throws:

IOException - an error reading input

binaryHeader

public byte[] binaryHeader()

Description copied from interface: ReadableBinary

Header for binary input. Will be automatically read by IOUtils when using readBinary().

Specified by:

binaryHeader in interface ReadableBinary

Specified by:

binaryHeader in interface WriteableBinary

Returns:

header

copy

public abstract SparseIntArray copy()

Deep copy the array.

Returns:

a deep copy of the array

add

public SparseIntArray add(SparseIntArray vector)

Add the values in the given vector to a copy of this array and return the result

Parameters:

vector - the vector to add

Returns:

the resultant vector

addInplace

public SparseIntArray addInplace(SparseIntArray vector)

Add the values in the given vector to this vector and return this

Parameters:

vector - the vector to add

Returns:

this

subtract

public SparseIntArray subtract(SparseIntArray vector)

Subtract the values in the given vector from a copy of this vector and return the result

Parameters:

vector - the array to add

Returns:

the resultant vector

subtractInplace

public SparseIntArray subtractInplace(SparseIntArray vector)

Subtract the values in the given vector from this array and return this

Parameters:

vector - the vector to add

Returns:

this

multiply

public SparseIntArray multiply(double value)

Copy this vector and multiply its values by a scalar

Parameters:

value - scalar multiplier

Returns:

the multiplied vector

multiplyInplace

public SparseIntArray multiplyInplace(double value)

Multiply the values inplace by a scalar and return this

Parameters:

value - scalar multiplier

Returns:

this

dotProduct

public double dotProduct(SparseIntArray vector)

Compute the dot product with another vector

Parameters:

vector - the other vector

Returns:

the dot product

maxValue

public int maxValue()

Returns:

the largest value in the array

minValue

public int minValue()

Returns:

the smallest value in the array

maxIndex

public int maxIndex()

Returns:

the index of the largest value in the array

minIndex

public int minIndex()

Returns:

the index of the smallest value in the array

reverse

public abstract SparseIntArray reverse()

Reverse the elements, returning this.

Returns:

this array

concatenateArrays

public static SparseIntArray concatenateArrays(SparseIntArray... arrays)

Concatenate multiple arrays into a single new array.

Parameters:

arrays - the arrays to concatenate.

Returns:

the new concatenated array

sumValues

public int sumValues()

Compute the sum of values

Returns:

the sum of all values

sumValuesSquared

public int sumValuesSquared()

Compute the sum of values squared

Returns:

the sum of all values

toArray

public int[] toArray()

Convert this sparse array to a dense array.

Be aware that calling this method results in an array of length being created. This could be very bad for performance.

Returns:

the dense array representation of this feature.

toArray

public int[] toArray(int[] array)

Convert this sparse array to a dense array. If the input array is longer than length, then it will be cleared and populated with the data held in this sparse array. If the input array is null or is smaller than length, then a new array will be allocated, filled and returned.

Be aware that calling this method may result in an array of length being created. This could be very bad for performance.

Parameters:

array - The array to fill or null.

Returns:

the dense array representation of this feature.

concatenate

public SparseIntArray concatenate(SparseIntArray... ins)

Description copied from interface: Concatenatable

Concatenate all the inputs with this, returning a new object that is the result of the concatenation.

Specified by:

concatenate in interface Concatenatable<SparseIntArray,SparseIntArray>

Parameters:

ins - the inputs

Returns:

the concatenated object

concatenate

public SparseIntArray concatenate(List<SparseIntArray> ins)

Description copied from interface: Concatenatable

Concatenate all the inputs with this, returning a new object that is the result of the concatenation.

Specified by:

concatenate in interface Concatenatable<SparseIntArray,SparseIntArray>

Parameters:

ins - the inputs

Returns:

the concatenated object