org.apache.mahout.cf.taste.impl.similarity.precompute

Class MultithreadedBatchItemSimilarities

java.lang.Object

org.apache.mahout.cf.taste.similarity.precompute.BatchItemSimilarities

org.apache.mahout.cf.taste.impl.similarity.precompute.MultithreadedBatchItemSimilarities

public class MultithreadedBatchItemSimilarities
extends BatchItemSimilarities

Precompute item similarities in parallel on a single machine. The recommender given to this class must use a DataModel that holds the interactions in memory (such as GenericDataModel or FileDataModel) as fast random access to the data is required

Constructor Summary

Constructors

Constructor and Description
MultithreadedBatchItemSimilarities(ItemBasedRecommender recommender, int similarItemsPerItem)
MultithreadedBatchItemSimilarities(ItemBasedRecommender recommender, int similarItemsPerItem, int batchSize)

Method Summary

Modifier and Type	Method and Description
int	computeItemSimilarities(int degreeOfParallelism, int maxDurationInHours, SimilarItemsWriter writer)

Methods inherited from class org.apache.mahout.cf.taste.similarity.precompute.BatchItemSimilarities

getRecommender, getSimilarItemsPerItem

Methods inherited from class java.lang.Object

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

Constructor Detail

MultithreadedBatchItemSimilarities

public MultithreadedBatchItemSimilarities(ItemBasedRecommender recommender,
                                          int similarItemsPerItem)

Parameters:

recommender - recommender to use

similarItemsPerItem - number of similar items to compute per item

MultithreadedBatchItemSimilarities

public MultithreadedBatchItemSimilarities(ItemBasedRecommender recommender,
                                          int similarItemsPerItem,
                                          int batchSize)

Parameters:

recommender - recommender to use

similarItemsPerItem - number of similar items to compute per item

batchSize - size of item batches sent to worker threads

Method Detail

computeItemSimilarities

public int computeItemSimilarities(int degreeOfParallelism,
                                   int maxDurationInHours,
                                   SimilarItemsWriter writer)
                            throws IOException

Specified by:

computeItemSimilarities in class BatchItemSimilarities

Parameters:

degreeOfParallelism - number of threads to use for the computation

maxDurationInHours - maximum duration of the computation

writer - SimilarItemsWriter used to persist the results

Returns:

the number of similarities precomputed

Throws:

IOException