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

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
              de.lmu.ifi.dbs.elki.datasource.filter.TFIDFNormalization

All Implemented Interfaces:

Normalization<SparseFloatVector>, ObjectFilter, InspectionUtilFrequentlyScanned, Parameterizable

public class TFIDFNormalization
extends InverseDocumentFrequencyNormalization

Perform full TF-IDF Normalization as commonly used in text mining. Each record is first normalized using "term frequencies" to sum up to 1. Then it is globally normalized using the Inverse Document Frequency, so rare terms are weighted stronger than common terms. Restore will only undo the IDF part of the normalization!

Field Summary

Fields inherited from class de.lmu.ifi.dbs.elki.datasource.filter.InverseDocumentFrequencyNormalization

idf, objcnt

Constructor Summary

TFIDFNormalization()
Constructor.

Method Summary

protected SparseFloatVector

filterSingleObject(SparseFloatVector featureVector) Normalize a single instance.

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

getInputTypeRestriction, prepareComplete, prepareProcessInstance, prepareStart, restore

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

Constructor Detail

TFIDFNormalization

public TFIDFNormalization()

Constructor.

Method Detail

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!

Overrides:

filterSingleObject in class InverseDocumentFrequencyNormalization

Parameters:

featureVector - Database object to normalize

Returns:

Normalized database object