de.lmu.ifi.dbs.elki.data

Class Subspace

java.lang.Object

de.lmu.ifi.dbs.elki.data.Subspace

Direct Known Subclasses:

CLIQUESubspace

public class Subspace
extends java.lang.Object

Represents a subspace of the original data space.

Since:

0.1

Author:

Elke Achtert

Field Summary

Fields

Modifier and Type	Field and Description
static java.util.Comparator<Subspace>	DIMENSION_COMPARATOR A comparator for subspaces based on their involved dimensions.
private int	dimensionality The dimensionality of this subspace.
private long[]	dimensions The dimensions building this subspace.

Constructor Summary

Constructors

Constructor and Description
Subspace(int dimension) Creates a new one-dimensional subspace of the original data space.
Subspace(long[] dimensions) Creates a new k-dimensional subspace of the original data space.

Method Summary

Modifier and Type	Method and Description
int	dimensionality() Returns the dimensionality of this subspace.
java.lang.String	dimensionsToString() Returns a string representation of the dimensions of this subspace separated by comma.
java.lang.String	dimensonsToString(java.lang.String sep) Returns a string representation of the dimensions of this subspace.
boolean	equals(java.lang.Object obj)
long[]	getDimensions() Returns the BitSet representing the dimensions of this subspace.
int	hashCode() Returns the hash code value of the dimensions of this subspace.
boolean	isSubspace(Subspace subspace) Returns true if this subspace is a subspace of the specified subspace, i.e.
Subspace	join(Subspace other) Joins this subspace with the specified subspace.
protected long[]	joinLastDimensions(Subspace other) Joins the dimensions of this subspace with the dimensions of the specified subspace.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

dimensions

private final long[] dimensions

The dimensions building this subspace.

dimensionality

private final int dimensionality

The dimensionality of this subspace.

DIMENSION_COMPARATOR

public static java.util.Comparator<Subspace> DIMENSION_COMPARATOR

A comparator for subspaces based on their involved dimensions. The subspaces are ordered according to the ordering of their dimensions.

If the two subspaces have different dimensionalities a negative integer or a positive integer will be returned if the dimensionality of the first subspace is less than or greater than the dimensionality of the second subspace. Otherwise the comparison works as follows: Let d1 and d2 be the first occurrences of pairwise unequal dimensions in the specified subspaces. Then a negative integer or a positive integer will be returned if d1 is less than or greater than d2. Otherwise the two subspaces have equal dimensions and zero will be returned.

Constructor Detail

Subspace

public Subspace(int dimension)

Creates a new one-dimensional subspace of the original data space.

Parameters:

dimension - the dimension building this subspace

Subspace

public Subspace(long[] dimensions)

Creates a new k-dimensional subspace of the original data space.

Parameters:

dimensions - the dimensions building this subspace

Method Detail

getDimensions

public final long[] getDimensions()

Returns the BitSet representing the dimensions of this subspace.

Returns:

the dimensions of this subspace

dimensionality

public final int dimensionality()

Returns the dimensionality of this subspace.

Returns:

the number of dimensions this subspace contains

join

public Subspace join(Subspace other)

Joins this subspace with the specified subspace. The join is only successful if both subspaces have the first k-1 dimensions in common (where k is the number of dimensions) and the last dimension of this subspace is less than the last dimension of the specified subspace.

Parameters:

other - the subspace to join

Returns:

the join of this subspace with the specified subspace if the join condition is fulfilled, null otherwise.

See Also:

joinLastDimensions(Subspace)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

dimensionsToString

public java.lang.String dimensionsToString()

Returns a string representation of the dimensions of this subspace separated by comma.

Returns:

a string representation of the dimensions of this subspace

dimensonsToString

public java.lang.String dimensonsToString(java.lang.String sep)

Returns a string representation of the dimensions of this subspace.

Parameters:

sep - the separator between the dimensions

Returns:

a string representation of the dimensions of this subspace

isSubspace

public boolean isSubspace(Subspace subspace)

Returns true if this subspace is a subspace of the specified subspace, i.e. if the set of dimensions building this subspace are contained in the set of dimensions building the specified subspace.

Parameters:

subspace - the subspace to test

Returns:

true if this subspace is a subspace of the specified subspace, false otherwise

joinLastDimensions

protected long[] joinLastDimensions(Subspace other)

Joins the dimensions of this subspace with the dimensions of the specified subspace. The join is only successful if both subspaces have the first k-1 dimensions in common (where k is the number of dimensions) and the last dimension of this subspace is less than the last dimension of the specified subspace.

Parameters:

other - the subspace to join

Returns:

the joined dimensions of this subspace with the dimensions of the specified subspace if the join condition is fulfilled, null otherwise.

hashCode

public int hashCode()

Returns the hash code value of the dimensions of this subspace.

Overrides:

hashCode in class java.lang.Object

Returns:

a hash code value for this subspace

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object