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

java.lang.Object
  extended by org.apache.mahout.cf.taste.similarity.precompute.BatchItemSimilarities
      extended by 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
MultithreadedBatchItemSimilarities(ItemBasedRecommender recommender, int similarItemsPerItem)
           
MultithreadedBatchItemSimilarities(ItemBasedRecommender recommender, int similarItemsPerItem, int batchSize)
           
 
Method Summary
 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


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