de.lmu.ifi.dbs.elki.algorithm.clustering.hierarchical

Class MatrixParadigm

java.lang.Object

de.lmu.ifi.dbs.elki.algorithm.clustering.hierarchical.MatrixParadigm

public class MatrixParadigm
extends java.lang.Object

Shared code for algorithms that work on a strict matrix paradigm. Note that this requires \(O(n^2)\) memory (and often \(O(n^3)\) runtime). This class bridges the gap from the relational (indexed by identifiers) and the matrix view (indexed by integers 0...n-1). While this will usually store (merge-) distances when clustering, it can store arbitrary doubles.

Since:

0.7.5

Author:

Erich Schubert

Field Summary

Fields

Modifier and Type	Field and Description
DBIDArrayIter	ix Two iterators to reference to objects.
DBIDArrayIter	iy Two iterators to reference to objects.
double[]	matrix Distance matrix (modifiable).
int	size Number of rows/columns.

Constructor Summary

Constructors

Constructor and Description
MatrixParadigm(DBIDs ids) Constructor.

Method Summary

Modifier and Type	Method and Description
double	get(int x, int y) Get a value from the (upper triangular) distance matrix.
MatrixParadigm	initializeWithDistances(DistanceQuery<?> dq) Initialize a distance matrix.
static int	triangleSize(int x) Compute the size of a complete x by x triangle (minus diagonal)

Methods inherited from class java.lang.Object

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

Field Detail

ix

public final DBIDArrayIter ix

Two iterators to reference to objects.

iy

public final DBIDArrayIter iy

Two iterators to reference to objects.

matrix

public final double[] matrix

Distance matrix (modifiable).

size

public final int size

Number of rows/columns.

Constructor Detail

MatrixParadigm

public MatrixParadigm(DBIDs ids)

Constructor.

Parameters:

ids - Database ids.

Method Detail

triangleSize

public static int triangleSize(int x)

Compute the size of a complete x by x triangle (minus diagonal)

Parameters:

x - Offset

Returns:

Size of complete triangle

get

public double get(int x,
                  int y)

Get a value from the (upper triangular) distance matrix. Note: in many cases, linear iteration over the matrix will be fastet than repeated calls to this method!

Parameters:

x - First object

y - Second object

Returns:

Distance

initializeWithDistances

public MatrixParadigm initializeWithDistances(DistanceQuery<?> dq)

Initialize a distance matrix.

Parameters:

dq - Distance query

Returns:

this