Package de.lmu.ifi.dbs.elki.database.ids

Database object identification and ID group handling API.


Interface Summary
ArrayDBIDs Interface for array based DBIDs.
ArrayModifiableDBIDs Array-oriented implementation of a modifiable DBID collection.
ArrayStaticDBIDs Unmodifiable, indexed DBIDs.
DBID Database ID object.
DBIDFactory Factory interface for generating DBIDs.
DBIDPair Immutable pair of two DBIDs.
DBIDRange Static DBID range.
DBIDs Interface for a collection of database references (IDs).
HashSetDBIDs Hash-organized DBIDs
HashSetModifiableDBIDs Set-oriented implementation of a modifiable DBID collection.
ModifiableDBIDs Interface for a generic modifiable DBID collection.
SetDBIDs Interface for DBIDs that support fast "set" operations, in particular "contains" lookups.
StaticDBIDs Unmodifiable DBIDs.
TreeSetDBIDs Marker for sorted, tree-organized DBIDs
TreeSetModifiableDBIDs Set-oriented implementation of a modifiable DBID collection.

Class Summary
DBIDUtil DBID Utility functions.
EmptyDBIDs Empty DBID collection.

Package de.lmu.ifi.dbs.elki.database.ids Description

Database object identification and ID group handling API. Database IDs (short: DBID) in ELKI are based on the factory pattern, to allow replacing the simple Integer-based DBIDs with more complex implementations, e.g. for use with external databases or to add tracking for debugging purposes. This also allows adding of more efficient implementations later on in a single place.

DBID interface:

The DBID object identifies a single object. The DBIDs hierarchy contains classes for handling groups (sets, arrays) of IDs, that can be seen as a two-dimensional matrix consisting
ArrayDBIDs HashSetDBIDs TreeSetDBIDs
ModifiableDBIDs ArrayModifiableDBIDs HashSetModifiableDBIDs TreeSetModifiableDBIDs
StaticDBIDs ArrayStaticDBIDs n/a n/a
StaticDBIDs are structures that cannot support modifications, but thus can be implemented more efficiently, for example as Interval. They are mostly used by the data sources. These interfaces cannot be instantiated, obviously. Instead, use the static DBIDFactory.FACTORY, which is also wrapped in the DBIDUtil class.


DBIDs allids = database.getIDs();
 // preallocate an array of initial capacity 123 
 ArrayModifiableDBIDs array = DBIDUtil.newArraySet(123);
 // new DBID hash set with minimum initial capacity
 ModifiableDBIDs hash = DBIDUtil.newHashSet();
 // initialize a tree set with the IDs of the database.
 ModifiableDBIDs tree = DBIDUtil.newTreeSet(database.getIDs());
 // add all DBIDs from the hash

Utility functions:

The static DBIDUtil class provides various utility functions, including:

Generic utility classes:

MergedDBIDs allows virtual concatenation of multiple DBIDs objects.

MaskedDBIDs allows masking an ArrayDBIDs with a BitSet.

Release 0.4.0 (2011-09-20_1324)