de.lmu.ifi.dbs.elki.database.relation

Class RelationUtil

java.lang.Object

de.lmu.ifi.dbs.elki.database.relation.RelationUtil

public final class RelationUtil
extends Object

Utility functions for handling database relation.

Constructor Summary

Constructors

Modifier	Constructor and Description
private	RelationUtil() Fake constructor: do not instantiate.

Method Summary

Methods

Modifier and Type	Method and Description
static <V extends FeatureVector<?>> VectorFieldTypeInformation<V>	assumeVectorField(Relation<V> relation) Get the vector field type information from a relation.
static int	dimensionality(Relation<? extends FeatureVector<?>> relation) Get the dimensionality of a database relation.
static <V extends FeatureVector<?>> String	getColumnLabel(Relation<? extends V> rel, int col) Get the column name or produce a generic label "Column XY".
static <V extends NumberVector<? extends N>,N extends Number> NumberVector.Factory<V,N>	getNumberVectorFactory(Relation<V> relation) Get the number vector factory of a database relation.
static double[][]	relationAsMatrix(Relation<? extends NumberVector<?>> relation, ArrayDBIDs ids) Copy a relation into a double matrix.

Methods inherited from class java.lang.Object

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

Constructor Detail

RelationUtil

private RelationUtil()

Fake constructor: do not instantiate.

Method Detail

assumeVectorField

public static <V extends FeatureVector<?>> VectorFieldTypeInformation<V> assumeVectorField(Relation<V> relation)

Get the vector field type information from a relation.

Type Parameters:

V - Vector type

Parameters:

relation - relation

Returns:

Vector field type information

getNumberVectorFactory

public static <V extends NumberVector<? extends N>,N extends Number> NumberVector.Factory<V,N> getNumberVectorFactory(Relation<V> relation)

Get the number vector factory of a database relation.

Type Parameters:

V - Vector type

N - Number type

Parameters:

relation - relation

Returns:

Vector field type information

dimensionality

public static int dimensionality(Relation<? extends FeatureVector<?>> relation)

Get the dimensionality of a database relation.

Parameters:

relation - relation

Returns:

Database dimensionality

relationAsMatrix

public static double[][] relationAsMatrix(Relation<? extends NumberVector<?>> relation,
                          ArrayDBIDs ids)

Copy a relation into a double matrix. This is not recommended unless you need to modify the data temporarily.

Parameters:

relation - Relation

ids - IDs, with well-defined order (i.e. array)

Returns:

Data matrix

getColumnLabel

public static <V extends FeatureVector<?>> String getColumnLabel(Relation<? extends V> rel,
                                                 int col)

Get the column name or produce a generic label "Column XY".

Type Parameters:

V - Vector type

Parameters:

rel - Relation

col - Column

Returns:

Label