org.openimaj.util.array

Class SparseFloatArray

java.lang.Object

org.openimaj.util.array.SparseFloatArray

All Implemented Interfaces:

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

Direct Known Subclasses:

SparseBinSearchFloatArray, SparseHashedFloatArray

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

A sparse array of float 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	SparseFloatArray.DualEntry An entry representing the values in two parallel SparseFloatArrays at the same index.
static class	SparseFloatArray.Entry An entry in a SparseFloatArray, 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
SparseFloatArray()

Method Summary

Modifier and Type	Method and Description
SparseFloatArray	add(SparseFloatArray vector) Add the values in the given vector to a copy of this array and return the result
SparseFloatArray	addInplace(SparseFloatArray 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.
SparseFloatArray	concatenate(List<SparseFloatArray> ins) Concatenate all the inputs with this, returning a new object that is the result of the concatenation.
SparseFloatArray	concatenate(SparseFloatArray... ins) Concatenate all the inputs with this, returning a new object that is the result of the concatenation.
static SparseFloatArray	concatenateArrays(SparseFloatArray... arrays) Concatenate multiple arrays into a single new array.
abstract SparseFloatArray	copy() Deep copy the array.
float	density()
double	dotProduct(SparseFloatArray vector) Compute the dot product with another vector
abstract Iterable<SparseFloatArray.Entry>	entries() Provide an iterator over the non-zero values.
abstract float	get(int index) Get the value at the given index.
abstract float	increment(int index, float value) Increment the value at the given index.
abstract int[]	indices()
Iterable<SparseFloatArray.DualEntry>	intersectEntries(SparseFloatArray 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()
float	maxValue()
int	minIndex()
float	minValue()
SparseFloatArray	multiply(double value) Copy this vector and multiply its values by a scalar
SparseFloatArray	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 SparseFloatArray	reverse() Reverse the elements, returning this.
abstract float	set(int index, float value) Set the value at the given index.
void	setLength(int newLength) Set the length of the array.
int	size()
SparseFloatArray	subtract(SparseFloatArray vector) Subtract the values in the given vector from a copy of this vector and return the result
SparseFloatArray	subtractInplace(SparseFloatArray vector) Subtract the values in the given vector from this array and return this
float	sumValues() Compute the sum of values
float	sumValuesSquared() Compute the sum of values squared
float[]	toArray() Convert this sparse array to a dense array.
float[]	toArray(float[] array) Convert this sparse array to a dense array.
Iterable<SparseFloatArray.DualEntry>	unionEntries(SparseFloatArray otherArray) Provide an iterator over the union of values present in both this array and another array.
abstract int	used()
abstract float[]	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

SparseFloatArray

public SparseFloatArray()

Method Detail

increment

public abstract float increment(int index,
                                float 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 float[] values()

Returns:

the packed non-zero valued entries of the array.

entries

public abstract Iterable<SparseFloatArray.Entry> entries()

Provide an iterator over the non-zero values.

Note: the SparseFloatArray.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 SparseFloatArray.Entry has no effect on the actual array).

Returns:

an iterator over the non-zero values.

unionEntries

public Iterable<SparseFloatArray.DualEntry> unionEntries(SparseFloatArray 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 SparseFloatArray.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 SparseFloatArray.DualEntry has no effect on the actual array).

Parameters:

otherArray - the second array

Returns:

an iterator over the non-zero values.

intersectEntries

public Iterable<SparseFloatArray.DualEntry> intersectEntries(SparseFloatArray 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 SparseFloatArray.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 SparseFloatArray.DualEntry has no effect on the actual array).

Parameters:

otherArray - the second array

Returns:

an iterator over the non-zero values.

get

public abstract float 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 float set(int index,
                          float 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 SparseFloatArray copy()

Deep copy the array.

Returns:

a deep copy of the array

add

public SparseFloatArray add(SparseFloatArray 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 SparseFloatArray addInplace(SparseFloatArray vector)

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

Parameters:

vector - the vector to add

Returns:

this

subtract

public SparseFloatArray subtract(SparseFloatArray 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 SparseFloatArray subtractInplace(SparseFloatArray vector)

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

Parameters:

vector - the vector to add

Returns:

this

multiply

public SparseFloatArray multiply(double value)

Copy this vector and multiply its values by a scalar

Parameters:

value - scalar multiplier

Returns:

the multiplied vector

multiplyInplace

public SparseFloatArray multiplyInplace(double value)

Multiply the values inplace by a scalar and return this

Parameters:

value - scalar multiplier

Returns:

this

dotProduct

public double dotProduct(SparseFloatArray vector)

Compute the dot product with another vector

Parameters:

vector - the other vector

Returns:

the dot product

maxValue

public float maxValue()

Returns:

the largest value in the array

minValue

public float 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 SparseFloatArray reverse()

Reverse the elements, returning this.

Returns:

this array

concatenateArrays

public static SparseFloatArray concatenateArrays(SparseFloatArray... arrays)

Concatenate multiple arrays into a single new array.

Parameters:

arrays - the arrays to concatenate.

Returns:

the new concatenated array

sumValues

public float sumValues()

Compute the sum of values

Returns:

the sum of all values

sumValuesSquared

public float sumValuesSquared()

Compute the sum of values squared

Returns:

the sum of all values

toArray

public float[] 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 float[] toArray(float[] 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 SparseFloatArray concatenate(SparseFloatArray... 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<SparseFloatArray,SparseFloatArray>

Parameters:

ins - the inputs

Returns:

the concatenated object

concatenate

public SparseFloatArray concatenate(List<SparseFloatArray> 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<SparseFloatArray,SparseFloatArray>

Parameters:

ins - the inputs

Returns:

the concatenated object