org.apache.spark.mllib.rdd

Class SlidingRDD<T>

Object

org.apache.spark.rdd.RDD<Object>

org.apache.spark.mllib.rdd.SlidingRDD<T>

All Implemented Interfaces:

java.io.Serializable, Logging

public class SlidingRDD<T>
extends RDD<Object>

Represents a RDD from grouping items of its parent RDD in fixed size blocks by passing a sliding window over them. The ordering is first based on the partition index and then the ordering of items within each partition. This is similar to sliding in Scala collections, except that it becomes an empty RDD if the window size is greater than the total number of items. It needs to trigger a Spark job if the parent RDD has more than one partitions. To make this operation efficient, the number of items per partition should be larger than the window size and the window size should be small, e.g., 2.

See Also:

RDDFunctions.sliding(int), Serialized Form

Constructor Summary

Constructors

Constructor and Description
SlidingRDD(RDD<T> parent, int windowSize, scala.reflect.ClassTag<T> evidence$1)

Method Summary

Methods

Modifier and Type	Method and Description
scala.collection.Iterator<Object>	compute(Partition split, TaskContext context) :: DeveloperApi :: Implemented by subclasses to compute a given partition.
Partition[]	getPartitions() Implemented by subclasses to return the set of partitions in this RDD.
scala.collection.Seq<String>	getPreferredLocations(Partition split) Optionally overridden by subclasses to specify placement preferences.
RDD<T>	parent()
int	windowSize()

Methods inherited from class org.apache.spark.rdd.RDD

aggregate, cache, cartesian, checkpoint, checkpointData, coalesce, collect, collect, collectPartitions, computeOrReadCheckpoint, conf, context, count, countApprox, countApproxDistinct, countApproxDistinct, countByValue, countByValueApprox, creationSite, dependencies, distinct, distinct, doCheckpoint, doubleRDDToDoubleRDDFunctions, elementClassTag, filter, filterWith, first, flatMap, flatMapWith, fold, foreach, foreachPartition, foreachWith, getCheckpointFile, getCreationSite, getNarrowAncestors, getStorageLevel, glom, groupBy, groupBy, groupBy, id, intersection, intersection, intersection, isCheckpointed, isEmpty, iterator, keyBy, map, mapPartitions, mapPartitionsWithContext, mapPartitionsWithIndex, mapPartitionsWithSplit, mapWith, markCheckpointed, max, min, name, numericRDDToDoubleRDDFunctions, partitioner, partitions, persist, persist, pipe, pipe, pipe, preferredLocations, randomSplit, rddToAsyncRDDActions, rddToOrderedRDDFunctions, rddToPairRDDFunctions, rddToSequenceFileRDDFunctions, reduce, repartition, retag, retag, sample, saveAsObjectFile, saveAsTextFile, saveAsTextFile, setName, sortBy, sparkContext, subtract, subtract, subtract, take, takeOrdered, takeSample, toArray, toDebugString, toJavaRDD, toLocalIterator, top, toString, treeAggregate, treeReduce, union, unpersist, zip, zipPartitions, zipPartitions, zipPartitions, zipPartitions, zipPartitions, zipPartitions, zipWithIndex, zipWithUniqueId

Methods inherited from class Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.spark.Logging

initializeIfNecessary, initializeLogging, isTraceEnabled, log_, log, logDebug, logDebug, logError, logError, logInfo, logInfo, logName, logTrace, logTrace, logWarning, logWarning

Constructor Detail

SlidingRDD

public SlidingRDD(RDD<T> parent,
          int windowSize,
          scala.reflect.ClassTag<T> evidence$1)

Method Detail

parent

public RDD<T> parent()

windowSize

public int windowSize()

compute

public scala.collection.Iterator<Object> compute(Partition split,
                                        TaskContext context)

Description copied from class: RDD

:: DeveloperApi :: Implemented by subclasses to compute a given partition.

Specified by:

compute in class RDD<Object>

getPreferredLocations

public scala.collection.Seq<String> getPreferredLocations(Partition split)

Description copied from class: RDD

Optionally overridden by subclasses to specify placement preferences.

getPartitions

public Partition[] getPartitions()

Description copied from class: RDD

Implemented by subclasses to return the set of partitions in this RDD. This method will only be called once, so it is safe to implement a time-consuming computation in it.