de.lmu.ifi.dbs.elki.database

Class DatabaseUtil

java.lang.Object

de.lmu.ifi.dbs.elki.database.DatabaseUtil

public final class DatabaseUtil
extends java.lang.Object

Class with Database-related utility functions such as centroid computation, covariances etc.

Since:

0.2

Author:

Erich Schubert

Constructor Summary

Constructors

Modifier	Constructor and Description
private	DatabaseUtil() Fake constructor: Do not instantiate!

Method Summary

Modifier and Type	Method and Description
static java.util.SortedSet<ClassLabel>	getClassLabels(Database database) Retrieves all class labels within the database.
static java.util.SortedSet<ClassLabel>	getClassLabels(Relation<? extends ClassLabel> database) Retrieves all class labels within the database.
static ArrayModifiableDBIDs	getObjectsByLabelMatch(Database database, java.util.regex.Pattern name_pattern) Find object by matching their labels.
static Relation<java.lang.String>	guessLabelRepresentation(Database database) Guess a potentially label-like representation, preferring class labels.
static Relation<java.lang.String>	guessObjectLabelRepresentation(Database database) Guess a potentially object label-like representation.
static <O> DistanceQuery<O>	precomputedDistanceQuery(Database database, Relation<O> relation, DistanceFunction<? super O> distf, Logging log) Get (or create) a precomputed distance query for the database.
static <O> KNNQuery<O>	precomputedKNNQuery(Database database, Relation<O> relation, DistanceFunction<? super O> distf, int k) Get (or create) a precomputed kNN query for the database.
static <O> KNNQuery<O>	precomputedKNNQuery(Database database, Relation<O> relation, DistanceQuery<O> dq, int k) Get (or create) a precomputed kNN query for the database.

Methods inherited from class java.lang.Object

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

Constructor Detail

DatabaseUtil

private DatabaseUtil()

Fake constructor: Do not instantiate!

Method Detail

guessLabelRepresentation

public static Relation<java.lang.String> guessLabelRepresentation(Database database)
                                                           throws NoSupportedDataTypeException

Guess a potentially label-like representation, preferring class labels.

Parameters:

database -

Returns:

string representation

Throws:

NoSupportedDataTypeException

guessObjectLabelRepresentation

public static Relation<java.lang.String> guessObjectLabelRepresentation(Database database)
                                                                 throws NoSupportedDataTypeException

Guess a potentially object label-like representation.

Parameters:

database -

Returns:

string representation

Throws:

NoSupportedDataTypeException

getClassLabels

public static java.util.SortedSet<ClassLabel> getClassLabels(Relation<? extends ClassLabel> database)

Retrieves all class labels within the database.

Parameters:

database - the database to be scanned for class labels

Returns:

a set comprising all class labels that are currently set in the database

getClassLabels

public static java.util.SortedSet<ClassLabel> getClassLabels(Database database)

Retrieves all class labels within the database.

Parameters:

database - the database to be scanned for class labels

Returns:

a set comprising all class labels that are currently set in the database

getObjectsByLabelMatch

public static ArrayModifiableDBIDs getObjectsByLabelMatch(Database database,
                                                          java.util.regex.Pattern name_pattern)

Find object by matching their labels.

Parameters:

database - Database to search in

name_pattern - Name to match against class or object label

Returns:

found cluster or it throws an exception.

precomputedKNNQuery

public static <O> KNNQuery<O> precomputedKNNQuery(Database database,
                                                  Relation<O> relation,
                                                  DistanceQuery<O> dq,
                                                  int k)

Get (or create) a precomputed kNN query for the database.

Parameters:

database - Database

relation - Relation

dq - Distance query

k - required number of neighbors

Returns:

KNNQuery for the given relation, that is precomputed.

precomputedKNNQuery

public static <O> KNNQuery<O> precomputedKNNQuery(Database database,
                                                  Relation<O> relation,
                                                  DistanceFunction<? super O> distf,
                                                  int k)

Get (or create) a precomputed kNN query for the database.

Parameters:

database - Database

relation - Relation

distf - Distance function

k - required number of neighbors

Returns:

KNNQuery for the given relation, that is precomputed.

precomputedDistanceQuery

public static <O> DistanceQuery<O> precomputedDistanceQuery(Database database,
                                                            Relation<O> relation,
                                                            DistanceFunction<? super O> distf,
                                                            Logging log)

Get (or create) a precomputed distance query for the database. This will usually force computing a distance matrix, unless there already is one.

Parameters:

database - Database

relation - Relation

distf - Distance function

log - Logger

Returns:

KNNQuery for the given relation, that is precomputed.