org.lenskit.data.ratings

Class RatingSummary

java.lang.Object

org.lenskit.data.ratings.RatingSummary

All Implemented Interfaces:

Serializable

@Shareable
 @DefaultProvider(value=RatingSummaryProvider.class)
public class RatingSummary
extends Object
implements Serializable

A summary of the ratings data.

Since:

3.0

See Also:

Serialized Form

Method Summary

Modifier and Type	Method and Description
static RatingSummary	create(DataAccessObject dao) Create a rating summary from a DAO.
double	getGlobalMean()
double	getItemMean(long item) Get the mean rating for an item.
Long2DoubleSortedArrayMap	getItemOffets()
double	getItemOffset(long item) Get the item’s average offset from global mean.
int	getItemRatingCount(long item) Get the number of ratings for the item.
LongSet	getItems()

Methods inherited from class java.lang.Object

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

Method Detail

create

public static RatingSummary create(DataAccessObject dao)

Create a rating summary from a DAO.

Parameters:

dao - The events.

Returns:

The rating summary.

getGlobalMean

public double getGlobalMean()

getItems

public LongSet getItems()

getItemMean

public double getItemMean(long item)

Get the mean rating for an item.

Parameters:

item - The item.

Returns:

The item’s mean rating, or Double.NaN if the item is absent.

getItemOffset

public double getItemOffset(long item)

Get the item’s average offset from global mean.

Parameters:

item - The item.

Returns:

The item’s average offset from the global mean rating, or 0 if the item is missing

getItemRatingCount

public int getItemRatingCount(long item)

Get the number of ratings for the item.

getItemOffets

public Long2DoubleSortedArrayMap getItemOffets()