org.apache.mahout.vectorizer.encoders

Class CachingValueEncoder

java.lang.Object

org.apache.mahout.vectorizer.encoders.FeatureVectorEncoder

org.apache.mahout.vectorizer.encoders.CachingValueEncoder

Direct Known Subclasses:

ConstantValueEncoder, ContinuousValueEncoder

public abstract class CachingValueEncoder
extends FeatureVectorEncoder

Provides basic hashing semantics for encoders where the probe locations depend only on the name of the variable.

Field Summary

Fields inherited from class org.apache.mahout.vectorizer.encoders.FeatureVectorEncoder

CONTINUOUS_VALUE_HASH_SEED, WORD_LIKE_VALUE_HASH_SEED

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	CachingValueEncoder(String name, int seed)

Method Summary

Methods

Modifier and Type	Method and Description
protected abstract int	getSeed()
protected int	hashForProbe(byte[] originalForm, int dataSize, String name, int probe) Provides the unique hash for a particular probe.
void	setProbes(int probes) Sets the number of locations in the feature vector that a value should be in.

Methods inherited from class org.apache.mahout.vectorizer.encoders.FeatureVectorEncoder

addToVector, addToVector, addToVector, addToVector, asString, bytesForString, getName, getProbes, getWeight, hash, hash, hash, hash, hash, hashesForProbe, isTraceEnabled, setTraceDictionary, trace, trace

Methods inherited from class java.lang.Object

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

Constructor Detail

CachingValueEncoder

protected CachingValueEncoder(String name,
                   int seed)

Method Detail

setProbes

public void setProbes(int probes)

Sets the number of locations in the feature vector that a value should be in. This causes the cached probe locations to be recomputed.

Overrides:

setProbes in class FeatureVectorEncoder

Parameters:

probes - Number of locations to increment.

getSeed

protected abstract int getSeed()

hashForProbe

protected int hashForProbe(byte[] originalForm,
               int dataSize,
               String name,
               int probe)

Description copied from class: FeatureVectorEncoder

Provides the unique hash for a particular probe. For all encoders except text, this is all that is needed and the default implementation of hashesForProbe will do the right thing. For text and similar values, hashesForProbe should be over-ridden and this method should not be used.

Specified by:

hashForProbe in class FeatureVectorEncoder

Parameters:

originalForm - The original byte array value

dataSize - The length of the vector being encoded

name - The name of the variable being encoded

probe - The probe number

Returns:

The hash of the current probe