org.mymedialite.itemrec
Class ItemKNN

java.lang.Object
  extended by org.mymedialite.itemrec.ItemRecommender
      extended by org.mymedialite.itemrec.KNN
          extended by org.mymedialite.itemrec.ItemKNN
All Implemented Interfaces:
java.lang.Cloneable, IItemSimilarityProvider, IRecommender
Direct Known Subclasses:
ItemAttributeKNN, WeightedItemKNN

public class ItemKNN
extends KNN
implements IItemSimilarityProvider

Unweighted k-nearest neighbor item-based collaborative filtering using cosine similarity. This recommender does NOT support incremental updates.


Field Summary
 
Fields inherited from class org.mymedialite.itemrec.KNN
correlation, k, nearest_neighbors
 
Fields inherited from class org.mymedialite.itemrec.ItemRecommender
feedback, maxItemID, maxUserID
 
Constructor Summary
ItemKNN()
           
 
Method Summary
 float getItemSimilarity(int item_id1, int item_id2)
          Get the similarity between two items.
 int[] getMostSimilarItems(int item_id, int n)
          Get the most similar items.
 double predict(int user_id, int item_id)
          Predict the rating or score for a given user-item combination.
 java.lang.String toString()
          Return a string representation of the recommender
 void train()
          Learn the model parameters of the recommender from the training data
 
Methods inherited from class org.mymedialite.itemrec.KNN
loadModel, loadModel, saveModel, saveModel
 
Methods inherited from class org.mymedialite.itemrec.ItemRecommender
canPredict, clone, getFeedback, setFeedback
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

ItemKNN

public ItemKNN()
Method Detail

train

public void train()
Description copied from interface: IRecommender
Learn the model parameters of the recommender from the training data

Specified by:
train in interface IRecommender
Specified by:
train in class ItemRecommender

predict

public double predict(int user_id,
                      int item_id)
Description copied from interface: IRecommender
Predict the rating or score for a given user-item combination.

Specified by:
predict in interface IRecommender
Specified by:
predict in class ItemRecommender
Parameters:
user_id - the user ID
item_id - the item ID
Returns:
the predicted score/rating for the given user-item combination

getItemSimilarity

public float getItemSimilarity(int item_id1,
                               int item_id2)
Description copied from interface: IItemSimilarityProvider
Get the similarity between two items.

Specified by:
getItemSimilarity in interface IItemSimilarityProvider
Parameters:
item_id1 - the ID of the first item
item_id2 - the ID of the second item
Returns:
the item similarity; higher means more similar

getMostSimilarItems

public int[] getMostSimilarItems(int item_id,
                                 int n)
Description copied from interface: IItemSimilarityProvider
Get the most similar items.

Specified by:
getMostSimilarItems in interface IItemSimilarityProvider
Parameters:
item_id - the ID of the item
n - the number of similar items to return
Returns:
the items most similar to a given item

toString

public java.lang.String toString()
Description copied from interface: IRecommender
Return a string representation of the recommender

Specified by:
toString in interface IRecommender
Overrides:
toString in class ItemRecommender
Returns:
the class name and all hyperparameters, separated by space characters.