de.lmu.ifi.dbs.elki.datasource.filter
Class InverseDocumentFrequencyNormalization

java.lang.Object
  de.lmu.ifi.dbs.elki.datasource.filter.AbstractConversionFilter<O,O>
      de.lmu.ifi.dbs.elki.datasource.filter.AbstractNormalization<SparseFloatVector>
          de.lmu.ifi.dbs.elki.datasource.filter.InverseDocumentFrequencyNormalization

All Implemented Interfaces:

Normalization<SparseFloatVector>, ObjectFilter, InspectionUtilFrequentlyScanned, Parameterizable

Direct Known Subclasses:

TFIDFNormalization

public class InverseDocumentFrequencyNormalization
extends AbstractNormalization<SparseFloatVector>

Normalization for text frequency vectors, using the inverse document frequency.

Field Summary

(package private) Map<Integer,Number>	idf The IDF storage
(package private) int	objcnt The number of objects in the dataset

Constructor Summary

InverseDocumentFrequencyNormalization()
Constructor.

Method Summary

protected SparseFloatVector	filterSingleObject(SparseFloatVector featureVector) Normalize a single instance.
protected SimpleTypeInformation<? super SparseFloatVector>	getInputTypeRestriction() Get the input type restriction used for negotiating the data query.
protected void	prepareComplete() Complete the initialization phase
protected void	prepareProcessInstance(SparseFloatVector featureVector) Process a single object during initialization.
protected boolean	prepareStart(SimpleTypeInformation<SparseFloatVector> in) Return "true" when the normalization needs initialization (two-pass filtering!)
SparseFloatVector	restore(SparseFloatVector featureVector) Transforms a feature vector to the original attribute ranges.

Methods inherited from class de.lmu.ifi.dbs.elki.datasource.filter.AbstractNormalization

convertedType, normalizeObjects, toString, transform

Methods inherited from class de.lmu.ifi.dbs.elki.datasource.filter.AbstractConversionFilter

filter

Methods inherited from class java.lang.Object

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

Methods inherited from interface de.lmu.ifi.dbs.elki.datasource.filter.ObjectFilter

filter

Field Detail

idf

Map<Integer,Number> idf

The IDF storage

objcnt

int objcnt

The number of objects in the dataset

Constructor Detail

InverseDocumentFrequencyNormalization

public InverseDocumentFrequencyNormalization()

Constructor.

Method Detail

prepareStart

protected boolean prepareStart(SimpleTypeInformation<SparseFloatVector> in)

Description copied from class: AbstractConversionFilter

Return "true" when the normalization needs initialization (two-pass filtering!)

Overrides:

prepareStart in class AbstractConversionFilter<SparseFloatVector,SparseFloatVector>

Parameters:

in - Input type information

Returns:

true or false

prepareProcessInstance

protected void prepareProcessInstance(SparseFloatVector featureVector)

Description copied from class: AbstractConversionFilter

Process a single object during initialization.

Overrides:

prepareProcessInstance in class AbstractConversionFilter<SparseFloatVector,SparseFloatVector>

Parameters:

featureVector - Object to process

prepareComplete

protected void prepareComplete()

Description copied from class: AbstractConversionFilter

Complete the initialization phase

Overrides:

prepareComplete in class AbstractConversionFilter<SparseFloatVector,SparseFloatVector>

filterSingleObject

protected SparseFloatVector filterSingleObject(SparseFloatVector featureVector)

Description copied from class: AbstractConversionFilter

Normalize a single instance. You can implement this as UnsupportedOperationException if you override both public "normalize" functions!

Specified by:

filterSingleObject in class AbstractConversionFilter<SparseFloatVector,SparseFloatVector>

Parameters:

featureVector - Database object to normalize

Returns:

Normalized database object

restore

public SparseFloatVector restore(SparseFloatVector featureVector)

Description copied from interface: Normalization

Transforms a feature vector to the original attribute ranges.

Parameters:

featureVector - a feature vector to be transformed into original space

Returns:

a feature vector transformed into original space corresponding to the given feature vector

getInputTypeRestriction

protected SimpleTypeInformation<? super SparseFloatVector> getInputTypeRestriction()

Description copied from class: AbstractConversionFilter

Get the input type restriction used for negotiating the data query.

Specified by:

getInputTypeRestriction in class AbstractConversionFilter<SparseFloatVector,SparseFloatVector>

Returns:

Type restriction