net.librec.recommender.item

Class RecommendedItemList

java.lang.Object

net.librec.recommender.item.RecommendedItemList

All Implemented Interfaces:

java.io.Serializable, RecommendedList

public class RecommendedItemList
extends java.lang.Object
implements RecommendedList, java.io.Serializable

Recommended Item List

Author:

WangYuFeng and Keqiang Wang

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
RecommendedItemList(int maxUserIdxParam) Constructs an empty list with the specified initial capacity(number of users).
RecommendedItemList(int maxUserIdxParam, int initCapacityParam) Constructs an empty list with the specified initial capacity(number of users).

Method Summary

Methods

Modifier and Type	Method and Description
boolean	addItemIdxList(int userIdx, java.util.ArrayList<ItemEntry<java.lang.Integer,java.lang.Double>> itemList) append the specified element to the end of this list.
boolean	addUserItemIdx(int userIdx, int itemIdx, double rating) Appends the specified element to the end of this list.
boolean	contains(int userIdx) Returns true if this list contains the specified userIdx.
java.util.Iterator<UserItemRatingEntry>	entryIterator() get the iterator of user-item-rating entry
double	getEntryValue(int userIdx, int itemIdx) Deprecated.
java.util.List<ItemEntry<java.lang.Integer,java.lang.Double>>	getItemIdxListByUserIdx(int userIdx) Returns the itemEntry of user index in this list.
int	getSize() the number of users (the number of ArrayList)
java.util.List<ItemEntry<java.lang.Integer,java.lang.Double>>	removeUserIdx(int userIdx) Removes the element at the specified position in this list.
boolean	setItemIdxList(int userIdx, java.util.List<ItemEntry<java.lang.Integer,java.lang.Double>> itemList) set the specified element to the end of this list.
int	size() Returns the number of elements in this list.
void	topNRank(int itemTopN) top n ranked Items for all userIdx
void	topNRankItemsByUser(int userIdx, int topN) top n ranked Items at user userIdx
java.util.Iterator<java.lang.Integer>	userIterator() get the iterator of user index

Methods inherited from class java.lang.Object

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

Constructor Detail

RecommendedItemList

public RecommendedItemList(int maxUserIdxParam)

Constructs an empty list with the specified initial capacity(number of users).

Parameters:

maxUserIdxParam - the max user index

Throws:

java.lang.IllegalArgumentException - if the specified initial capacity is negative

RecommendedItemList

public RecommendedItemList(int maxUserIdxParam,
                   int initCapacityParam)

Constructs an empty list with the specified initial capacity(number of users).

Parameters:

maxUserIdxParam - the max user index

initCapacityParam - initial capacity

Throws:

java.lang.IllegalArgumentException - if the specified initial capacity is negative

Method Detail

setItemIdxList

public boolean setItemIdxList(int userIdx,
                     java.util.List<ItemEntry<java.lang.Integer,java.lang.Double>> itemList)

set the specified element to the end of this list.

Parameters:

userIdx - user index

itemList - element to be appended to this list

Returns:

true (as specified by Collection.add(E))

addItemIdxList

public boolean addItemIdxList(int userIdx,
                     java.util.ArrayList<ItemEntry<java.lang.Integer,java.lang.Double>> itemList)

append the specified element to the end of this list.

Parameters:

userIdx - user index

itemList - element to be appended to this list

Returns:

true (as specified by Collection.add(E))

addUserItemIdx

public boolean addUserItemIdx(int userIdx,
                     int itemIdx,
                     double rating)

Appends the specified element to the end of this list.

Specified by:

addUserItemIdx in interface RecommendedList

Parameters:

userIdx - user index

itemIdx - item index

rating - rating value

Returns:

true (as specified by Collection.add(E))

getItemIdxListByUserIdx

public java.util.List<ItemEntry<java.lang.Integer,java.lang.Double>> getItemIdxListByUserIdx(int userIdx)
                                                                                      throws java.lang.IndexOutOfBoundsException

Returns the itemEntry of user index in this list.

Specified by:

getItemIdxListByUserIdx in interface RecommendedList

Parameters:

userIdx - user index

Returns:

the itemEntry of user index in this list

Throws:

java.lang.IndexOutOfBoundsException

getEntryValue

@Deprecated
@LibrecWaring(value="It is best not to use this method! Too slow and the complexity is O(itemIdxList.size()).")
public double getEntryValue(int userIdx,
                                                int itemIdx)
                     throws java.lang.IndexOutOfBoundsException

Deprecated.

Returns the element at the specified position in this list.

Specified by:

getEntryValue in interface RecommendedList

Parameters:

userIdx - index of the element to return

itemIdx - index of the element to return

Returns:

the element at the specified position in this list

Throws:

java.lang.IndexOutOfBoundsException

removeUserIdx

public java.util.List<ItemEntry<java.lang.Integer,java.lang.Double>> removeUserIdx(int userIdx)
                                                                            throws java.lang.IndexOutOfBoundsException

Removes the element at the specified position in this list. Shifts any subsequent elements to the left (subtracts one from their indices).

Specified by:

removeUserIdx in interface RecommendedList

Parameters:

userIdx - user index

Returns:

the element that was removed from the list

Throws:

java.lang.IndexOutOfBoundsException

topNRank

public void topNRank(int itemTopN)

top n ranked Items for all userIdx

Specified by:

topNRank in interface RecommendedList

Parameters:

itemTopN - top n ranked Items

topNRankItemsByUser

public void topNRankItemsByUser(int userIdx,
                       int topN)

top n ranked Items at user userIdx

Specified by:

topNRankItemsByUser in interface RecommendedList

Parameters:

userIdx - user userIdx

topN - top n ranked Items

contains

public boolean contains(int userIdx)

Returns true if this list contains the specified userIdx. More formally, returns true if and only if this list contains userIdx e such that (userIdx==null ? e==null : userIdx.equals(e)).

Specified by:

contains in interface RecommendedList

Parameters:

userIdx - element whose presence in this list is to be tested

Returns:

true if this list contains the specified userIdx

getSize

public int getSize()

the number of users (the number of ArrayList)

Returns:

the number of users

userIterator

public java.util.Iterator<java.lang.Integer> userIterator()

get the iterator of user index

Specified by:

userIterator in interface RecommendedList

Returns:

user index iterator

entryIterator

public java.util.Iterator<UserItemRatingEntry> entryIterator()

get the iterator of user-item-rating entry

Specified by:

entryIterator in interface RecommendedList

Returns:

user item-rating-entry iterator

size

public int size()

Description copied from interface: RecommendedList

Returns the number of elements in this list. If this list contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.

Specified by:

size in interface RecommendedList

Returns:

the number of elements in this list