org.apache.mahout.cf.taste.impl.model

Class AbstractDataModel

java.lang.Object

org.apache.mahout.cf.taste.impl.model.AbstractDataModel

All Implemented Interfaces:

Serializable, Refreshable, DataModel

Direct Known Subclasses:

FileDataModel, GenericBooleanPrefDataModel, GenericDataModel

public abstract class AbstractDataModel
extends Object
implements DataModel

Contains some features common to all implementations.

See Also:

Serialized Form

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractDataModel()

Method Summary

Modifier and Type	Method and Description
float	getMaxPreference()
float	getMinPreference()
protected void	setMaxPreference(float maxPreference)
protected void	setMinPreference(float minPreference)

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.mahout.cf.taste.model.DataModel

getItemIDs, getItemIDsFromUser, getNumItems, getNumUsers, getNumUsersWithPreferenceFor, getNumUsersWithPreferenceFor, getPreferencesForItem, getPreferencesFromUser, getPreferenceTime, getPreferenceValue, getUserIDs, hasPreferenceValues, removePreference, setPreference

Methods inherited from interface org.apache.mahout.cf.taste.common.Refreshable

refresh

Constructor Detail

AbstractDataModel

protected AbstractDataModel()

Method Detail

getMaxPreference

public float getMaxPreference()

Specified by:

getMaxPreference in interface DataModel

Returns:

the maximum preference value that is possible in the current problem domain being evaluated. For example, if the domain is movie ratings on a scale of 1 to 5, this should be 5. While a Recommender may estimate a preference value above 5.0, it isn't "fair" to consider that the system is actually suggesting an impossible rating of, say, 5.4 stars. In practice the application would cap this estimate to 5.0. Since evaluators evaluate the difference between estimated and actual value, this at least prevents this effect from unfairly penalizing a Recommender

setMaxPreference

protected void setMaxPreference(float maxPreference)

getMinPreference

public float getMinPreference()

Specified by:

getMinPreference in interface DataModel

See Also:

DataModel.getMaxPreference()

setMinPreference

protected void setMinPreference(float minPreference)