org.grouplens.lenskit.vectors

Class ImmutableSparseVector

java.lang.Object

org.grouplens.lenskit.vectors.SparseVector

org.grouplens.lenskit.vectors.ImmutableSparseVector

All Implemented Interfaces:

Serializable, Iterable<VectorEntry>

@Immutable
public final class ImmutableSparseVector
extends SparseVector
implements Serializable

Immutable sparse vectors. These vectors cannot be changed, even by other code, and are therefore safe to store and are thread-safe.

Author:

GroupLens Research

See Also:

Serialized Form

Compatibility: Public

Constructor Summary

Constructors

Modifier	Constructor and Description
	ImmutableSparseVector() Create a new, empty immutable sparse vector.
protected	ImmutableSparseVector(long[] ks, double[] vs) Construct a new vector from existing arrays.
protected	ImmutableSparseVector(long[] ks, double[] vs, int sz) Construct a new sparse vector from pre-existing arrays.
	ImmutableSparseVector(Long2DoubleMap ratings) Create a new immutable sparse vector from a map of ratings.

Method Summary

Methods

Modifier and Type	Method and Description
ImmutableSparseVector	channel(Symbol channelSymbol) Fetch the channel stored under a particular symbol.
<K> org.grouplens.lenskit.vectors.ImmutableTypedSideChannel<K>	channel(TypedSymbol<K> channelSymbol) Fetch the channel stored under a particular typed symbol.
Set<Symbol>	getChannels() Retrieve all symbols that map to side channels for this vector.
Set<TypedSymbol<?>>	getTypedChannels() Retrieve all symbols that map to typed side channels for this vector.
boolean	hasChannel(Symbol channelSymbol) Return whether this sparse vector has a channel stored under a particular symbol.
boolean	hasChannel(TypedSymbol<?> channelSymbol) Return whether this sparse vector has a typed channel stored under a particular typed symbol.
ImmutableSparseVector	immutable() Return an immutable snapshot of this sparse vector.
double	mean() Compute and return the mean of the vector's values.
MutableSparseVector	mutableCopy() Return a mutable copy of this sparse vector.
double	norm() Compute and return the L2 norm (Euclidian length) of the vector.
double	sum() Compute and return the L1 norm (sum) of the vector.

Methods inherited from class org.grouplens.lenskit.vectors.SparseVector

containsKey, countCommonKeys, dot, equals, fast, fast, fastIterator, fastIterator, fastPointer, fastPointer, findIndex, get, get, get, hashCode, isEmpty, iterator, keyDomain, keysByValue, keysByValue, keySet, pointer, pointer, size, toString, values

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ImmutableSparseVector

public ImmutableSparseVector()

Create a new, empty immutable sparse vector.

ImmutableSparseVector

public ImmutableSparseVector(Long2DoubleMap ratings)

Create a new immutable sparse vector from a map of ratings.

Parameters:

ratings - The ratings to make a vector from. Its key set is used as the vector's key domain.

ImmutableSparseVector

protected ImmutableSparseVector(long[] ks,
                     double[] vs)

Construct a new vector from existing arrays. It is assumed that the keys are sorted and duplicate-free, and that the values is the same length. The key array is the key domain, and all keys are considered used. No new keys can be added to this vector. Clients should call the wrap() method rather than directly calling this constructor.

Parameters:

ks - The array of keys backing this vector. They must be sorted.

vs - The array of values backing this vector.

ImmutableSparseVector

protected ImmutableSparseVector(long[] ks,
                     double[] vs,
                     int sz)

Construct a new sparse vector from pre-existing arrays. These arrays must be sorted in key order and cannot contain duplicate keys; this condition is not checked.

Parameters:

ks - The key array (will be the key domain).

vs - The value array.

sz - The length to actually use.

Method Detail

immutable

public ImmutableSparseVector immutable()

Description copied from class: SparseVector

Return an immutable snapshot of this sparse vector. The new vector's key domain will be equal to the SparseVector.keySet() of this vector.

Specified by:

immutable in class SparseVector

Returns:

An immutable sparse vector whose contents are the same as this vector. If the vector is already immutable, the returned object may be identical.

mutableCopy

public MutableSparseVector mutableCopy()

Description copied from class: SparseVector

Return a mutable copy of this sparse vector. The key domain of the mutable vector will be the same as this vector's key domain.

Specified by:

mutableCopy in class SparseVector

Returns:

A mutable sparse vector which can be modified without modifying this vector.

hasChannel

public boolean hasChannel(Symbol channelSymbol)

Description copied from class: SparseVector

Return whether this sparse vector has a channel stored under a particular symbol. (Symbols are sort of like names, but more efficient.)

Specified by:

hasChannel in class SparseVector

Parameters:

channelSymbol - the symbol under which the channel was stored in the vector.

Returns:

whether this vector has such a channel right now.

hasChannel

public boolean hasChannel(TypedSymbol<?> channelSymbol)

Description copied from class: SparseVector

Return whether this sparse vector has a typed channel stored under a particular typed symbol. (Symbols are sort of like names, but more efficient.)

Specified by:

hasChannel in class SparseVector

Parameters:

channelSymbol - the typed symbol under which the channel was stored in the vector.

Returns:

whether this vector has such a channel right now.

channel

public ImmutableSparseVector channel(Symbol channelSymbol)

Description copied from class: SparseVector

Fetch the channel stored under a particular symbol.

Specified by:

channel in class SparseVector

Parameters:

channelSymbol - the symbol under which the channel was/is stored in the vector.

Returns:

the channel, which is itself a sparse vector.

channel

public <K> org.grouplens.lenskit.vectors.ImmutableTypedSideChannel<K> channel(TypedSymbol<K> channelSymbol)

Description copied from class: SparseVector

Fetch the channel stored under a particular typed symbol.

Specified by:

channel in class SparseVector

Parameters:

channelSymbol - the typed symbol under which the channel was/is stored in the vector.

Returns:

the channel, which is itself a map from the key domain to objects of the channel's type

getChannels

public Set<Symbol> getChannels()

Description copied from class: SparseVector

Retrieve all symbols that map to side channels for this vector.

Specified by:

getChannels in class SparseVector

Returns:

A set of symbols, each of which identifies a side channel of the vector.

getTypedChannels

public Set<TypedSymbol<?>> getTypedChannels()

Description copied from class: SparseVector

Retrieve all symbols that map to typed side channels for this vector.

Specified by:

getTypedChannels in class SparseVector

Returns:

A set of symbols, each of which identifies a side channel of the vector.

norm

public double norm()

Description copied from class: SparseVector

Compute and return the L2 norm (Euclidian length) of the vector.

Overrides:

norm in class SparseVector

Returns:

The L2 norm of the vector

sum

public double sum()

Description copied from class: SparseVector

Compute and return the L1 norm (sum) of the vector.

Overrides:

sum in class SparseVector

Returns:

the sum of the vector's values

mean

public double mean()

Description copied from class: SparseVector

Compute and return the mean of the vector's values.

Overrides:

mean in class SparseVector

Returns:

the mean of the vector