de.lmu.ifi.dbs.elki.algorithm.projection

Interface AffinityMatrix

All Known Implementing Classes:

DenseAffinityMatrix, SparseAffinityMatrix

public interface AffinityMatrix

Abstraction interface for an affinity matrix.

Since:

0.7.5

Author:

Erich Schubert

Method Summary

Modifier and Type	Method and Description
double	get(int i, int j) Get an entry by absolute position.
int	iter(int x) Iterator over non-zero features only.
int	iterAdvance(int x, int iter) Advance the iterator to the next position.
DBIDArrayIter	iterDBIDs() Array iterator over the stored objects.
int	iterDim(int x, int iter) Get the dimension an iterator points to.
boolean	iterValid(int x, int iter) Test the iterator position for validity.
double	iterValue(int x, int iter) Get the value an iterator points to.
void	scale(double d) Scale the whole matrix with a constant factor d.
int	size() Number of rows.

Method Detail

scale

void scale(double d)

Scale the whole matrix with a constant factor d. This is used to add/remove early exaggeration of tSNE.

Parameters:

d - Scaling factor.

size

int size()

Number of rows.

Returns:

Size

get

double get(int i,
           int j)

Get an entry by absolute position. Note: this may be expensive on sparse matrixes.

Parameters:

i - Row

j - Column

Returns:

Entry

iter

int iter(int x)

Iterator over non-zero features only. Note: depending on the underlying implementation, this may or may not be the dimension. Use iterDim(int, int) to get the actual dimension. In fact, usually this will be the ith non-zero value, assuming an array representation. Think of this number as an iterator. But for efficiency, it has a primitive type, so it does not require garbage collection. With Java 10 value types, we will likely be able to make this both type-safe and highly efficient again. Intended usage:

 
 for (int iter = v.iter(x); v.iterValid(x, iter); iter = v.iterAdvance(x, iter)) {
   final int dim = v.iterDim(x, iter);
   final int val = v.iterValue(x, iter);
 }
 
 

Important: you need to use the return value of iterAdvance for the next iteration, or you will have an endless loop.

Parameters:

x - Point to get the neighbors for

Returns:

Identifier for the first non-zero dimension, not necessarily the dimension!

iterDim

int iterDim(int x,
            int iter)

Get the dimension an iterator points to.

Parameters:

iter - Iterator position

Returns:

Dimension the iterator refers to

iterValue

double iterValue(int x,
                 int iter)

Get the value an iterator points to.

Parameters:

iter - Iterator position

Returns:

Dimension the iterator refers to

iterAdvance

int iterAdvance(int x,
                int iter)

Advance the iterator to the next position.

Parameters:

iter - Previous iterator position

Returns:

Next iterator position

iterValid

boolean iterValid(int x,
                  int iter)

Test the iterator position for validity.

Parameters:

iter - Iterator position

Returns:

true when it refers to a valid position.

iterDBIDs

DBIDArrayIter iterDBIDs()

Array iterator over the stored objects.

Returns:

DBID iterator