at.tuwien.ifs.somtoolbox.data.distance

Class RandomAccessFileInputVectorDistanceMatrix

java.lang.Object

at.tuwien.ifs.somtoolbox.data.distance.InputVectorDistanceMatrix

at.tuwien.ifs.somtoolbox.data.distance.RandomAccessFileInputVectorDistanceMatrix

public class RandomAccessFileInputVectorDistanceMatrix
extends InputVectorDistanceMatrix

A distance matrix based on a binary RandomAccessFile. This implementation does not read the matrix into the memory, and is thus suited especially for big datasets.

The file is built as follows:

• One integer value, giving the number of vectors
• A series of double values representing the upper-right half of the symmetric distance matrix, not containing the values in the diagonal itself (as they are all 0).
  Thus, there are (n-1)! double values, and the matrix file contains the following (x, y) tuples:

   [(2,1) (3,1) (4,1) (5,1) (6,1)]
   [      (3,2) (4,2) (5,1) (6,2)]
   [            (4,3) (5,3) (6,3)]
   [                  (5,4) (6,4)]
   [                        (6,5)]
   [                             ]
   

• The name of the metric used, as String (until the end of the file).

Version:

$Id: RandomAccessFileInputVectorDistanceMatrix.java 3706 2010-07-20 11:07:54Z mayer $

Author:

Rudolf Mayer

Field Summary

Fields

Modifier and Type	Field and Description
private static int	BYTES_CHAR
private static int	BYTES_DOUBLE
static int	BYTES_HEADER
private java.io.RandomAccessFile	file

Fields inherited from class at.tuwien.ifs.somtoolbox.data.distance.InputVectorDistanceMatrix

inputLabels, metric, numVectors

Constructor Summary

Constructors

Constructor and Description
RandomAccessFileInputVectorDistanceMatrix(java.lang.String fileName)

Method Summary

Modifier and Type	Method and Description
double	getDistance(int x, int y) Return the distance between input vectors x and y.
DistanceMetric	getMetric()
protected static long	getOffset(long x, long y, long numVectors) Find the offset of a specific value in the linear order

Methods inherited from class at.tuwien.ifs.somtoolbox.data.distance.InputVectorDistanceMatrix

columns, equals, flatArraySize, getDistances, getDistancesFlat, getDistancesFlatAsMatrix, getInputLabels, getNNearest, initFromFile, numVectors, rows, toString

Methods inherited from class java.lang.Object

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

Field Detail

BYTES_HEADER

public static final int BYTES_HEADER

See Also:

Constant Field Values

BYTES_CHAR

private static final int BYTES_CHAR

See Also:

Constant Field Values

BYTES_DOUBLE

private static final int BYTES_DOUBLE

See Also:

Constant Field Values

file

private java.io.RandomAccessFile file

Constructor Detail

RandomAccessFileInputVectorDistanceMatrix

public RandomAccessFileInputVectorDistanceMatrix(java.lang.String fileName)
                                          throws java.io.IOException,
                                                 SOMToolboxException

Throws:

java.io.IOException

SOMToolboxException

Method Detail

getMetric

public DistanceMetric getMetric()

Overrides:

getMetric in class InputVectorDistanceMatrix

getDistance

public double getDistance(int x,
                          int y)

Description copied from class: InputVectorDistanceMatrix

Return the distance between input vectors x and y.

Specified by:

getDistance in class InputVectorDistanceMatrix

getOffset

protected static long getOffset(long x,
                                long y,
                                long numVectors)

Find the offset of a specific value in the linear order