RDD (Spark 2.2.2 JavaDoc)

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

All Implemented Interfaces:

java.io.Serializable, Logging

Direct Known Subclasses:

BaseRRDD, CoGroupedRDD, EdgeRDD, HadoopRDD, JdbcRDD, NewHadoopRDD, PartitionPruningRDD, ShuffledRDD, UnionRDD, VertexRDD
```
public abstract class RDD<T>
extends Object
implements scala.Serializable, Logging
```
A Resilient Distributed Dataset (RDD), the basic abstraction in Spark. Represents an immutable, partitioned collection of elements that can be operated on in parallel. This class contains the basic operations available on all RDDs, such as map, filter, and persist. In addition, PairRDDFunctions contains operations available only on RDDs of key-value pairs, such as groupByKey and join; DoubleRDDFunctions contains operations available only on RDDs of Doubles; and SequenceFileRDDFunctions contains operations available on RDDs that can be saved as SequenceFiles. All operations are automatically available on any RDD of the right type (e.g. RDD[(Int, Int)] through implicit.
Internally, each RDD is characterized by five main properties:
- A list of partitions - A function for computing each split - A list of dependencies on other RDDs - Optionally, a Partitioner for key-value RDDs (e.g. to say that the RDD is hash-partitioned) - Optionally, a list of preferred locations to compute each split on (e.g. block locations for an HDFS file)
All of the scheduling and execution in Spark is done based on these methods, allowing each RDD to implement its own way of computing itself. Indeed, users can implement custom RDDs (e.g. for reading data from a new storage system) by overriding these functions. Please refer to the Spark paper for more details on RDD internals.

See Also:

Serialized Form

Constructor Summary

Constructors
Constructor and Description
`RDD(RDD<?> oneParent, scala.reflect.ClassTag<T> evidence$2)` Construct an RDD with just a one-to-one dependency on one parent
`RDD(SparkContext _sc, scala.collection.Seq<Dependency<?>> deps, scala.reflect.ClassTag<T> evidence$1)`

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`<U> U`	`aggregate(U zeroValue, scala.Function2<U,T,U> seqOp, scala.Function2<U,U,U> combOp, scala.reflect.ClassTag<U> evidence$30)` Aggregate the elements of each partition, and then the results for all the partitions, using given combine functions and a neutral "zero value".
`RDD<T>`	`cache()` Persist this RDD with the default storage level (`MEMORY_ONLY`).
`<U> RDD<scala.Tuple2<T,U>>`	`cartesian(RDD<U> other, scala.reflect.ClassTag<U> evidence$5)` Return the Cartesian product of this RDD and another one, that is, the RDD of all pairs of elements (a, b) where a is in `this` and b is in `other`.
`void`	`checkpoint()` Mark this RDD for checkpointing.
`RDD<T>`	`coalesce(int numPartitions, boolean shuffle, scala.Option<PartitionCoalescer> partitionCoalescer, scala.math.Ordering<T> ord)` Return a new RDD that is reduced into `numPartitions` partitions.
`Object`	`collect()` Return an array that contains all of the elements in this RDD.
`<U> RDD<U>`	`collect(scala.PartialFunction<T,U> f, scala.reflect.ClassTag<U> evidence$29)` Return an RDD that contains all matching values by applying `f`.
`abstract scala.collection.Iterator<T>`	`compute(Partition split, TaskContext context)` :: DeveloperApi :: Implemented by subclasses to compute a given partition.
`SparkContext`	`context()` The `SparkContext` that this RDD was created on.
`long`	`count()` Return the number of elements in the RDD.
`PartialResult<BoundedDouble>`	`countApprox(long timeout, double confidence)` Approximate version of count() that returns a potentially incomplete result within a timeout, even if not all tasks have finished.
`long`	`countApproxDistinct(double relativeSD)` Return approximate number of distinct elements in the RDD.
`long`	`countApproxDistinct(int p, int sp)` Return approximate number of distinct elements in the RDD.
`scala.collection.Map<T,Object>`	`countByValue(scala.math.Ordering<T> ord)` Return the count of each unique value in this RDD as a local map of (value, count) pairs.
`PartialResult<scala.collection.Map<T,BoundedDouble>>`	`countByValueApprox(long timeout, double confidence, scala.math.Ordering<T> ord)` Approximate version of countByValue().
`scala.collection.Seq<Dependency<?>>`	`dependencies()` Get the list of dependencies of this RDD, taking into account whether the RDD is checkpointed or not.
`RDD<T>`	`distinct()` Return a new RDD containing the distinct elements in this RDD.
`RDD<T>`	`distinct(int numPartitions, scala.math.Ordering<T> ord)` Return a new RDD containing the distinct elements in this RDD.
`static DoubleRDDFunctions`	`doubleRDDToDoubleRDDFunctions(RDD<Object> rdd)`
`RDD<T>`	`filter(scala.Function1<T,Object> f)` Return a new RDD containing only the elements that satisfy a predicate.
`T`	`first()` Return the first element in this RDD.
`<U> RDD<U>`	`flatMap(scala.Function1<T,scala.collection.TraversableOnce<U>> f, scala.reflect.ClassTag<U> evidence$4)` Return a new RDD by first applying a function to all elements of this RDD, and then flattening the results.
`T`	`fold(T zeroValue, scala.Function2<T,T,T> op)` Aggregate the elements of each partition, and then the results for all the partitions, using a given associative function and a neutral "zero value".
`void`	`foreach(scala.Function1<T,scala.runtime.BoxedUnit> f)` Applies a function f to all elements of this RDD.
`void`	`foreachPartition(scala.Function1<scala.collection.Iterator<T>,scala.runtime.BoxedUnit> f)` Applies a function f to each partition of this RDD.
`scala.Option<String>`	`getCheckpointFile()` Gets the name of the directory to which this RDD was checkpointed.
`int`	`getNumPartitions()` Returns the number of partitions of this RDD.
`StorageLevel`	`getStorageLevel()` Get the RDD's current storage level, or StorageLevel.NONE if none is set.
`RDD<Object>`	`glom()` Return an RDD created by coalescing all elements within each partition into an array.
`<K> RDD<scala.Tuple2<K,scala.collection.Iterable<T>>>`	`groupBy(scala.Function1<T,K> f, scala.reflect.ClassTag<K> kt)` Return an RDD of grouped items.
`<K> RDD<scala.Tuple2<K,scala.collection.Iterable<T>>>`	`groupBy(scala.Function1<T,K> f, int numPartitions, scala.reflect.ClassTag<K> kt)` Return an RDD of grouped elements.
`<K> RDD<scala.Tuple2<K,scala.collection.Iterable<T>>>`	`groupBy(scala.Function1<T,K> f, Partitioner p, scala.reflect.ClassTag<K> kt, scala.math.Ordering<K> ord)` Return an RDD of grouped items.
`int`	`id()` A unique ID for this RDD (within its SparkContext).
`RDD<T>`	`intersection(RDD<T> other)` Return the intersection of this RDD and another one.
`RDD<T>`	`intersection(RDD<T> other, int numPartitions)` Return the intersection of this RDD and another one.
`RDD<T>`	`intersection(RDD<T> other, Partitioner partitioner, scala.math.Ordering<T> ord)` Return the intersection of this RDD and another one.
`boolean`	`isCheckpointed()` Return whether this RDD is checkpointed and materialized, either reliably or locally.
`boolean`	`isEmpty()`
`scala.collection.Iterator<T>`	`iterator(Partition split, TaskContext context)` Internal method to this RDD; will read from cache if applicable, or otherwise compute it.
`<K> RDD<scala.Tuple2<K,T>>`	`keyBy(scala.Function1<T,K> f)` Creates tuples of the elements in this RDD by applying `f`.
`RDD<T>`	`localCheckpoint()` Mark this RDD for local checkpointing using Spark's existing caching layer.
`<U> RDD<U>`	`map(scala.Function1<T,U> f, scala.reflect.ClassTag<U> evidence$3)` Return a new RDD by applying a function to all elements of this RDD.
`<U> RDD<U>`	`mapPartitions(scala.Function1<scala.collection.Iterator<T>,scala.collection.Iterator<U>> f, boolean preservesPartitioning, scala.reflect.ClassTag<U> evidence$6)` Return a new RDD by applying a function to each partition of this RDD.
`<U> RDD<U>`	`mapPartitionsWithIndex(scala.Function2<Object,scala.collection.Iterator<T>,scala.collection.Iterator<U>> f, boolean preservesPartitioning, scala.reflect.ClassTag<U> evidence$9)` Return a new RDD by applying a function to each partition of this RDD, while tracking the index of the original partition.
`T`	`max(scala.math.Ordering<T> ord)` Returns the max of this RDD as defined by the implicit Ordering[T].
`T`	`min(scala.math.Ordering<T> ord)` Returns the min of this RDD as defined by the implicit Ordering[T].
`String`	`name()` A friendly name for this RDD
`static <T> DoubleRDDFunctions`	`numericRDDToDoubleRDDFunctions(RDD<T> rdd, scala.math.Numeric<T> num)`
`scala.Option<Partitioner>`	`partitioner()` Optionally overridden by subclasses to specify how they are partitioned.
`Partition[]`	`partitions()` Get the array of partitions of this RDD, taking into account whether the RDD is checkpointed or not.
`RDD<T>`	`persist()` Persist this RDD with the default storage level (`MEMORY_ONLY`).
`RDD<T>`	`persist(StorageLevel newLevel)` Set this RDD's storage level to persist its values across operations after the first time it is computed.
`RDD<String>`	`pipe(scala.collection.Seq<String> command, scala.collection.Map<String,String> env, scala.Function1<scala.Function1<String,scala.runtime.BoxedUnit>,scala.runtime.BoxedUnit> printPipeContext, scala.Function2<T,scala.Function1<String,scala.runtime.BoxedUnit>,scala.runtime.BoxedUnit> printRDDElement, boolean separateWorkingDir, int bufferSize, String encoding)` Return an RDD created by piping elements to a forked external process.
`RDD<String>`	`pipe(String command)` Return an RDD created by piping elements to a forked external process.
`RDD<String>`	`pipe(String command, scala.collection.Map<String,String> env)` Return an RDD created by piping elements to a forked external process.
`scala.collection.Seq<String>`	`preferredLocations(Partition split)` Get the preferred locations of a partition, taking into account whether the RDD is checkpointed.
`RDD<T>[]`	`randomSplit(double[] weights, long seed)` Randomly splits this RDD with the provided weights.
`static <T> AsyncRDDActions<T>`	`rddToAsyncRDDActions(RDD<T> rdd, scala.reflect.ClassTag<T> evidence$34)`
`static <K,V> OrderedRDDFunctions<K,V,scala.Tuple2<K,V>>`	`rddToOrderedRDDFunctions(RDD<scala.Tuple2<K,V>> rdd, scala.math.Ordering<K> evidence$35, scala.reflect.ClassTag<K> evidence$36, scala.reflect.ClassTag<V> evidence$37)`
`static <K,V> PairRDDFunctions<K,V>`	`rddToPairRDDFunctions(RDD<scala.Tuple2<K,V>> rdd, scala.reflect.ClassTag<K> kt, scala.reflect.ClassTag<V> vt, scala.math.Ordering<K> ord)`
`static <K,V> SequenceFileRDDFunctions<K,V>`	`rddToSequenceFileRDDFunctions(RDD<scala.Tuple2<K,V>> rdd, scala.reflect.ClassTag<K> kt, scala.reflect.ClassTag<V> vt, <any> keyWritableFactory, <any> valueWritableFactory)`
`T`	`reduce(scala.Function2<T,T,T> f)` Reduces the elements of this RDD using the specified commutative and associative binary operator.
`RDD<T>`	`repartition(int numPartitions, scala.math.Ordering<T> ord)` Return a new RDD that has exactly numPartitions partitions.
`RDD<T>`	`sample(boolean withReplacement, double fraction, long seed)` Return a sampled subset of this RDD.
`void`	`saveAsObjectFile(String path)` Save this RDD as a SequenceFile of serialized objects.
`void`	`saveAsTextFile(String path)` Save this RDD as a text file, using string representations of elements.
`void`	`saveAsTextFile(String path, Class<? extends org.apache.hadoop.io.compress.CompressionCodec> codec)` Save this RDD as a compressed text file, using string representations of elements.
`RDD<T>`	`setName(String _name)` Assign a name to this RDD
`<K> RDD<T>`	`sortBy(scala.Function1<T,K> f, boolean ascending, int numPartitions, scala.math.Ordering<K> ord, scala.reflect.ClassTag<K> ctag)` Return this RDD sorted by the given key function.
`SparkContext`	`sparkContext()` The SparkContext that created this RDD.
`RDD<T>`	`subtract(RDD<T> other)` Return an RDD with the elements from `this` that are not in `other`.
`RDD<T>`	`subtract(RDD<T> other, int numPartitions)` Return an RDD with the elements from `this` that are not in `other`.
`RDD<T>`	`subtract(RDD<T> other, Partitioner p, scala.math.Ordering<T> ord)` Return an RDD with the elements from `this` that are not in `other`.
`Object`	`take(int num)` Take the first num elements of the RDD.
`Object`	`takeOrdered(int num, scala.math.Ordering<T> ord)` Returns the first k (smallest) elements from this RDD as defined by the specified implicit Ordering[T] and maintains the ordering.
`Object`	`takeSample(boolean withReplacement, int num, long seed)` Return a fixed-size sampled subset of this RDD in an array
`String`	`toDebugString()` A description of this RDD and its recursive dependencies for debugging.
`JavaRDD<T>`	`toJavaRDD()`
`scala.collection.Iterator<T>`	`toLocalIterator()` Return an iterator that contains all of the elements in this RDD.
`Object`	`top(int num, scala.math.Ordering<T> ord)` Returns the top k (largest) elements from this RDD as defined by the specified implicit Ordering[T] and maintains the ordering.
`String`	`toString()`
`<U> U`	`treeAggregate(U zeroValue, scala.Function2<U,T,U> seqOp, scala.Function2<U,U,U> combOp, int depth, scala.reflect.ClassTag<U> evidence$31)` Aggregates the elements of this RDD in a multi-level tree pattern.
`T`	`treeReduce(scala.Function2<T,T,T> f, int depth)` Reduces the elements of this RDD in a multi-level tree pattern.
`RDD<T>`	`union(RDD<T> other)` Return the union of this RDD and another one.
`RDD<T>`	`unpersist(boolean blocking)` Mark the RDD as non-persistent, and remove all blocks for it from memory and disk.
`<U> RDD<scala.Tuple2<T,U>>`	`zip(RDD<U> other, scala.reflect.ClassTag<U> evidence$10)` Zips this RDD with another one, returning key-value pairs with the first element in each RDD, second element in each RDD, etc.
`<B,V> RDD<V>`	`zipPartitions(RDD<B> rdd2, boolean preservesPartitioning, scala.Function2<scala.collection.Iterator<T>,scala.collection.Iterator<B>,scala.collection.Iterator<V>> f, scala.reflect.ClassTag<B> evidence$11, scala.reflect.ClassTag<V> evidence$12)` Zip this RDD's partitions with one (or more) RDD(s) and return a new RDD by applying a function to the zipped partitions.
`<B,V> RDD<V>`	`zipPartitions(RDD<B> rdd2, scala.Function2<scala.collection.Iterator<T>,scala.collection.Iterator<B>,scala.collection.Iterator<V>> f, scala.reflect.ClassTag<B> evidence$13, scala.reflect.ClassTag<V> evidence$14)`
`<B,C,V> RDD<V>`	`zipPartitions(RDD<B> rdd2, RDD<C> rdd3, boolean preservesPartitioning, scala.Function3<scala.collection.Iterator<T>,scala.collection.Iterator<B>,scala.collection.Iterator<C>,scala.collection.Iterator<V>> f, scala.reflect.ClassTag<B> evidence$15, scala.reflect.ClassTag<C> evidence$16, scala.reflect.ClassTag<V> evidence$17)`
`<B,C,V> RDD<V>`	`zipPartitions(RDD<B> rdd2, RDD<C> rdd3, scala.Function3<scala.collection.Iterator<T>,scala.collection.Iterator<B>,scala.collection.Iterator<C>,scala.collection.Iterator<V>> f, scala.reflect.ClassTag<B> evidence$18, scala.reflect.ClassTag<C> evidence$19, scala.reflect.ClassTag<V> evidence$20)`
`<B,C,D,V> RDD<V>`	`zipPartitions(RDD<B> rdd2, RDD<C> rdd3, RDD<D> rdd4, boolean preservesPartitioning, scala.Function4<scala.collection.Iterator<T>,scala.collection.Iterator<B>,scala.collection.Iterator<C>,scala.collection.Iterator<D>,scala.collection.Iterator<V>> f, scala.reflect.ClassTag<B> evidence$21, scala.reflect.ClassTag<C> evidence$22, scala.reflect.ClassTag<D> evidence$23, scala.reflect.ClassTag<V> evidence$24)`
`<B,C,D,V> RDD<V>`	`zipPartitions(RDD<B> rdd2, RDD<C> rdd3, RDD<D> rdd4, scala.Function4<scala.collection.Iterator<T>,scala.collection.Iterator<B>,scala.collection.Iterator<C>,scala.collection.Iterator<D>,scala.collection.Iterator<V>> f, scala.reflect.ClassTag<B> evidence$25, scala.reflect.ClassTag<C> evidence$26, scala.reflect.ClassTag<D> evidence$27, scala.reflect.ClassTag<V> evidence$28)`
`RDD<scala.Tuple2<T,Object>>`	`zipWithIndex()` Zips this RDD with its element indices.
`RDD<scala.Tuple2<T,Object>>`	`zipWithUniqueId()` Zips this RDD with generated unique Long ids.

Methods inherited from class Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.spark.internal.Logging
initializeLogging, initializeLogIfNecessary, isTraceEnabled, log_, log, logDebug, logDebug, logError, logError, logInfo, logInfo, logName, logTrace, logTrace, logWarning, logWarning

- Constructor Detail
 - RDD
```
public RDD(SparkContext _sc,
 scala.collection.Seq<Dependency<?>> deps,
 scala.reflect.ClassTag<T> evidence$1)
```
 - RDD
```
public RDD(RDD<?> oneParent,
 scala.reflect.ClassTag<T> evidence$2)
```
 Construct an RDD with just a one-to-one dependency on one parent
- Method Detail
 - rddToPairRDDFunctions
```
public static <K,V> PairRDDFunctions<K,V> rddToPairRDDFunctions(RDD<scala.Tuple2<K,V>> rdd,
 scala.reflect.ClassTag<K> kt,
 scala.reflect.ClassTag<V> vt,
 scala.math.Ordering<K> ord)
```
 - rddToAsyncRDDActions
```
public static <T> AsyncRDDActions<T> rddToAsyncRDDActions(RDD<T> rdd,
 scala.reflect.ClassTag<T> evidence$34)
```
 - rddToSequenceFileRDDFunctions
```
public static <K,V> SequenceFileRDDFunctions<K,V> rddToSequenceFileRDDFunctions(RDD<scala.Tuple2<K,V>> rdd,
 scala.reflect.ClassTag<K> kt,
 scala.reflect.ClassTag<V> vt,
 <any> keyWritableFactory,
 <any> valueWritableFactory)
```
 - rddToOrderedRDDFunctions
```
public static <K,V> OrderedRDDFunctions<K,V,scala.Tuple2<K,V>> rddToOrderedRDDFunctions(RDD<scala.Tuple2<K,V>> rdd,
 scala.math.Ordering<K> evidence$35,
 scala.reflect.ClassTag<K> evidence$36,
 scala.reflect.ClassTag<V> evidence$37)
```
 - doubleRDDToDoubleRDDFunctions
```
public static DoubleRDDFunctions doubleRDDToDoubleRDDFunctions(RDD<Object> rdd)
```
 - numericRDDToDoubleRDDFunctions
```
public static <T> DoubleRDDFunctions numericRDDToDoubleRDDFunctions(RDD<T> rdd,
 scala.math.Numeric<T> num)
```
 - compute
```
public abstract scala.collection.Iterator<T> compute(Partition split,
 TaskContext context)
```
 :: DeveloperApi :: Implemented by subclasses to compute a given partition.
 
 Parameters:
 
 split - (undocumented)
 
 context - (undocumented)
 
 Returns:
 
 (undocumented)
 - partitioner
```
public scala.Option<Partitioner> partitioner()
```
 Optionally overridden by subclasses to specify how they are partitioned.
 - sparkContext
```
public SparkContext sparkContext()
```
 The SparkContext that created this RDD.
 - id
```
public int id()
```
 A unique ID for this RDD (within its SparkContext).
 - name
```
public String name()
```
 A friendly name for this RDD
 - setName
```
public RDD<T> setName(String _name)
```
 Assign a name to this RDD
 - persist
```
public RDD<T> persist(StorageLevel newLevel)
```
 Set this RDD's storage level to persist its values across operations after the first time it is computed. This can only be used to assign a new storage level if the RDD does not have a storage level set yet. Local checkpointing is an exception.
 
 Parameters:
 
 newLevel - (undocumented)
 
 Returns:
 
 (undocumented)
 - persist
```
public RDD<T> persist()
```
 Persist this RDD with the default storage level (MEMORY_ONLY).
 
 Returns:
 
 (undocumented)
 - cache
```
public RDD<T> cache()
```
 Persist this RDD with the default storage level (MEMORY_ONLY).
 
 Returns:
 
 (undocumented)
 - unpersist
```
public RDD<T> unpersist(boolean blocking)
```
 Mark the RDD as non-persistent, and remove all blocks for it from memory and disk.
 
 Parameters:
 
 blocking - Whether to block until all blocks are deleted.
 
 Returns:
 
 This RDD.
 - getStorageLevel
```
public StorageLevel getStorageLevel()
```
 Get the RDD's current storage level, or StorageLevel.NONE if none is set.
 - dependencies
```
public final scala.collection.Seq<Dependency<?>> dependencies()
```
 Get the list of dependencies of this RDD, taking into account whether the RDD is checkpointed or not.
 
 Returns:
 
 (undocumented)
 - partitions
```
public final Partition[] partitions()
```
 Get the array of partitions of this RDD, taking into account whether the RDD is checkpointed or not.
 
 Returns:
 
 (undocumented)
 - getNumPartitions
```
public final int getNumPartitions()
```
 Returns the number of partitions of this RDD.
 
 Returns:
 
 (undocumented)
 - preferredLocations
```
public final scala.collection.Seq<String> preferredLocations(Partition split)
```
 Get the preferred locations of a partition, taking into account whether the RDD is checkpointed.
 
 Parameters:
 
 split - (undocumented)
 
 Returns:
 
 (undocumented)
 - iterator
```
public final scala.collection.Iterator<T> iterator(Partition split,
 TaskContext context)
```
 Internal method to this RDD; will read from cache if applicable, or otherwise compute it. This should ''not'' be called by users directly, but is available for implementors of custom subclasses of RDD.
 
 Parameters:
 
 split - (undocumented)
 
 context - (undocumented)
 
 Returns:
 
 (undocumented)
 - map
```
public  RDD map(scala.Function1<T,U> f,
 scala.reflect.ClassTag evidence$3)
```
 Return a new RDD by applying a function to all elements of this RDD.
 
 Parameters:
 
 f - (undocumented)
 
 evidence$3 - (undocumented)
 
 Returns:
 
 (undocumented)
 - flatMap
```
public  RDD flatMap(scala.Function1<T,scala.collection.TraversableOnce> f,
 scala.reflect.ClassTag evidence$4)
```
 Return a new RDD by first applying a function to all elements of this RDD, and then flattening the results.
 
 Parameters:
 
 f - (undocumented)
 
 evidence$4 - (undocumented)
 
 Returns:
 
 (undocumented)
 - filter
```
public RDD<T> filter(scala.Function1<T,Object> f)
```
 Return a new RDD containing only the elements that satisfy a predicate.
 
 Parameters:
 
 f - (undocumented)
 
 Returns:
 
 (undocumented)
 - distinct
```
public RDD<T> distinct(int numPartitions,
 scala.math.Ordering<T> ord)
```
 Return a new RDD containing the distinct elements in this RDD.
 
 Parameters:
 
 numPartitions - (undocumented)
 
 ord - (undocumented)
 
 Returns:
 
 (undocumented)
 - distinct
```
public RDD<T> distinct()
```
 Return a new RDD containing the distinct elements in this RDD.
 
 Returns:
 
 (undocumented)
 - repartition
```
public RDD<T> repartition(int numPartitions,
 scala.math.Ordering<T> ord)
```
 Return a new RDD that has exactly numPartitions partitions.
 Can increase or decrease the level of parallelism in this RDD. Internally, this uses a shuffle to redistribute data.
 If you are decreasing the number of partitions in this RDD, consider using coalesce, which can avoid performing a shuffle.
 
 Parameters:
 
 numPartitions - (undocumented)
 
 ord - (undocumented)
 
 Returns:
 
 (undocumented)
 - coalesce
```
public RDD<T> coalesce(int numPartitions,
 boolean shuffle,
 scala.Option<PartitionCoalescer> partitionCoalescer,
 scala.math.Ordering<T> ord)
```
 Return a new RDD that is reduced into numPartitions partitions.
 This results in a narrow dependency, e.g. if you go from 1000 partitions to 100 partitions, there will not be a shuffle, instead each of the 100 new partitions will claim 10 of the current partitions. If a larger number of partitions is requested, it will stay at the current number of partitions.
 However, if you're doing a drastic coalesce, e.g. to numPartitions = 1, this may result in your computation taking place on fewer nodes than you like (e.g. one node in the case of numPartitions = 1). To avoid this, you can pass shuffle = true. This will add a shuffle step, but means the current upstream partitions will be executed in parallel (per whatever the current partitioning is).
 
 Parameters:
 
 numPartitions - (undocumented)
 
 shuffle - (undocumented)
 
 partitionCoalescer - (undocumented)
 
 ord - (undocumented)
 
 Returns:
 
 (undocumented)
 
 Note:
 
 With shuffle = true, you can actually coalesce to a larger number of partitions. This is useful if you have a small number of partitions, say 100, potentially with a few partitions being abnormally large. Calling coalesce(1000, shuffle = true) will result in 1000 partitions with the data distributed using a hash partitioner. The optional partition coalescer passed in must be serializable.
 - sample
```
public RDD<T> sample(boolean withReplacement,
 double fraction,
 long seed)
```
 Return a sampled subset of this RDD.
 
 Parameters:
 
 withReplacement - can elements be sampled multiple times (replaced when sampled out)
 
 fraction - expected size of the sample as a fraction of this RDD's size without replacement: probability that each element is chosen; fraction must be [0, 1] with replacement: expected number of times each element is chosen; fraction must be greater than or equal to 0
 
 seed - seed for the random number generator
 
 Returns:
 
 (undocumented)
 
 Note:
 
 This is NOT guaranteed to provide exactly the fraction of the count of the given RDD.
 - randomSplit
```
public RDD<T>[] randomSplit(double[] weights,
 long seed)
```
 Randomly splits this RDD with the provided weights.
 
 Parameters:
 
 weights - weights for splits, will be normalized if they don't sum to 1
 
 seed - random seed
 
 Returns:
 
 split RDDs in an array
 - takeSample
```
public Object takeSample(boolean withReplacement,
 int num,
 long seed)
```
 Return a fixed-size sampled subset of this RDD in an array
 
 Parameters:
 
 withReplacement - whether sampling is done with replacement
 
 num - size of the returned sample
 
 seed - seed for the random number generator
 
 Returns:
 
 sample of specified size in an array
 
 Note:
 
 this method should only be used if the resulting array is expected to be small, as all the data is loaded into the driver's memory.
 - union
```
public RDD<T> union(RDD<T> other)
```
 Return the union of this RDD and another one. Any identical elements will appear multiple times (use .distinct() to eliminate them).
 
 Parameters:
 
 other - (undocumented)
 
 Returns:
 
 (undocumented)
 - sortBy
```
public <K> RDD<T> sortBy(scala.Function1<T,K> f,
 boolean ascending,
 int numPartitions,
 scala.math.Ordering<K> ord,
 scala.reflect.ClassTag<K> ctag)
```
 Return this RDD sorted by the given key function.
 
 Parameters:
 
 f - (undocumented)
 
 ascending - (undocumented)
 
 numPartitions - (undocumented)
 
 ord - (undocumented)
 
 ctag - (undocumented)
 
 Returns:
 
 (undocumented)
 - intersection
```
public RDD<T> intersection(RDD<T> other)
```
 Return the intersection of this RDD and another one. The output will not contain any duplicate elements, even if the input RDDs did.
 
 Parameters:
 
 other - (undocumented)
 
 Returns:
 
 (undocumented)
 
 Note:
 
 This method performs a shuffle internally.
 - intersection
```
public RDD<T> intersection(RDD<T> other,
 Partitioner partitioner,
 scala.math.Ordering<T> ord)
```
 Return the intersection of this RDD and another one. The output will not contain any duplicate elements, even if the input RDDs did.
 
 Parameters:
 
 partitioner - Partitioner to use for the resulting RDD
 
 other - (undocumented)
 
 ord - (undocumented)
 
 Returns:
 
 (undocumented)
 
 Note:
 
 This method performs a shuffle internally.
 - intersection
```
public RDD<T> intersection(RDD<T> other,
 int numPartitions)
```
 Return the intersection of this RDD and another one. The output will not contain any duplicate elements, even if the input RDDs did. Performs a hash partition across the cluster
 
 Parameters:
 
 numPartitions - How many partitions to use in the resulting RDD
 
 other - (undocumented)
 
 Returns:
 
 (undocumented)
 
 Note:
 
 This method performs a shuffle internally.
 - glom
```
public RDD<Object> glom()
```
 Return an RDD created by coalescing all elements within each partition into an array.
 
 Returns:
 
 (undocumented)
 - cartesian
```
public  RDD<scala.Tuple2<T,U>> cartesian(RDD other,
 scala.reflect.ClassTag evidence$5)
```
 Return the Cartesian product of this RDD and another one, that is, the RDD of all pairs of elements (a, b) where a is in this and b is in other.
 
 Parameters:
 
 other - (undocumented)
 
 evidence$5 - (undocumented)
 
 Returns:
 
 (undocumented)
 - groupBy
```
public <K> RDD<scala.Tuple2<K,scala.collection.Iterable<T>>> groupBy(scala.Function1<T,K> f,
 scala.reflect.ClassTag<K> kt)
```
 Return an RDD of grouped items. Each group consists of a key and a sequence of elements mapping to that key. The ordering of elements within each group is not guaranteed, and may even differ each time the resulting RDD is evaluated.
 
 Parameters:
 
 f - (undocumented)
 
 kt - (undocumented)
 
 Returns:
 
 (undocumented)
 
 Note:
 
 This operation may be very expensive. If you are grouping in order to perform an aggregation (such as a sum or average) over each key, using PairRDDFunctions.aggregateByKey or PairRDDFunctions.reduceByKey will provide much better performance.
 - groupBy
```
public <K> RDD<scala.Tuple2<K,scala.collection.Iterable<T>>> groupBy(scala.Function1<T,K> f,
 int numPartitions,
 scala.reflect.ClassTag<K> kt)
```
 Return an RDD of grouped elements. Each group consists of a key and a sequence of elements mapping to that key. The ordering of elements within each group is not guaranteed, and may even differ each time the resulting RDD is evaluated.
 
 Parameters:
 
 f - (undocumented)
 
 numPartitions - (undocumented)
 
 kt - (undocumented)
 
 Returns:
 
 (undocumented)
 
 Note:
 
 This operation may be very expensive. If you are grouping in order to perform an aggregation (such as a sum or average) over each key, using PairRDDFunctions.aggregateByKey or PairRDDFunctions.reduceByKey will provide much better performance.
 - groupBy
```
public <K> RDD<scala.Tuple2<K,scala.collection.Iterable<T>>> groupBy(scala.Function1<T,K> f,
 Partitioner p,
 scala.reflect.ClassTag<K> kt,
 scala.math.Ordering<K> ord)
```
 Return an RDD of grouped items. Each group consists of a key and a sequence of elements mapping to that key. The ordering of elements within each group is not guaranteed, and may even differ each time the resulting RDD is evaluated.
 
 Parameters:
 
 f - (undocumented)
 
 p - (undocumented)
 
 kt - (undocumented)
 
 ord - (undocumented)
 
 Returns:
 
 (undocumented)
 
 Note:
 
 This operation may be very expensive. If you are grouping in order to perform an aggregation (such as a sum or average) over each key, using PairRDDFunctions.aggregateByKey or PairRDDFunctions.reduceByKey will provide much better performance.
 - pipe
```
public RDD<String> pipe(String command)
```
 Return an RDD created by piping elements to a forked external process.
 
 Parameters:
 
 command - (undocumented)
 
 Returns:
 
 (undocumented)
 - pipe
```
public RDD<String> pipe(String command,
 scala.collection.Map<String,String> env)
```
 Return an RDD created by piping elements to a forked external process.
 
 Parameters:
 
 command - (undocumented)
 
 env - (undocumented)
 
 Returns:
 
 (undocumented)
 - pipe
```
public RDD<String> pipe(scala.collection.Seq<String> command,
 scala.collection.Map<String,String> env,
 scala.Function1<scala.Function1<String,scala.runtime.BoxedUnit>,scala.runtime.BoxedUnit> printPipeContext,
 scala.Function2<T,scala.Function1<String,scala.runtime.BoxedUnit>,scala.runtime.BoxedUnit> printRDDElement,
 boolean separateWorkingDir,
 int bufferSize,
 String encoding)
```
 Return an RDD created by piping elements to a forked external process. The resulting RDD is computed by executing the given process once per partition. All elements of each input partition are written to a process's stdin as lines of input separated by a newline. The resulting partition consists of the process's stdout output, with each line of stdout resulting in one element of the output partition. A process is invoked even for empty partitions.
 The print behavior can be customized by providing two functions.
 Parameters:
 
 command - command to run in forked process.
 
 env - environment variables to set.
 
 printPipeContext - Before piping elements, this function is called as an opportunity to pipe context data. Print line function (like out.println) will be passed as printPipeContext's parameter.
 printRDDElement - Use this function to customize how to pipe elements. This function will be called with each RDD element as the 1st parameter, and the print line function (like out.println()) as the 2nd parameter. An example of pipe the RDD data of groupBy() in a streaming way, instead of constructing a huge String to concat all the elements:
 def printRDDElement(record:(String, Seq[String]), f:String=>Unit) = for (e <- record._2) {f(e)}
 separateWorkingDir - Use separate working directories for each task.
 
 bufferSize - Buffer size for the stdin writer for the piped process.
 
 encoding - Char encoding used for interacting (via stdin, stdout and stderr) with the piped process
 
 Returns:
 
 the result RDD
 - mapPartitions
```
public  RDD mapPartitions(scala.Function1<scala.collection.Iterator<T>,scala.collection.Iterator> f,
 boolean preservesPartitioning,
 scala.reflect.ClassTag evidence$6)
```
 Return a new RDD by applying a function to each partition of this RDD.
 preservesPartitioning indicates whether the input function preserves the partitioner, which should be false unless this is a pair RDD and the input function doesn't modify the keys.
 
 Parameters:
 
 f - (undocumented)
 
 preservesPartitioning - (undocumented)
 
 evidence$6 - (undocumented)
 
 Returns:
 
 (undocumented)
 - mapPartitionsWithIndex
```
public  RDD mapPartitionsWithIndex(scala.Function2<Object,scala.collection.Iterator<T>,scala.collection.Iterator> f,
 boolean preservesPartitioning,
 scala.reflect.ClassTag evidence$9)
```
 Return a new RDD by applying a function to each partition of this RDD, while tracking the index of the original partition.
 preservesPartitioning indicates whether the input function preserves the partitioner, which should be false unless this is a pair RDD and the input function doesn't modify the keys.
 
 Parameters:
 
 f - (undocumented)
 
 preservesPartitioning - (undocumented)
 
 evidence$9 - (undocumented)
 
 Returns:
 
 (undocumented)
 - zip
```
public  RDD<scala.Tuple2<T,U>> zip(RDD other,
 scala.reflect.ClassTag evidence$10)
```
 Zips this RDD with another one, returning key-value pairs with the first element in each RDD, second element in each RDD, etc. Assumes that the two RDDs have the *same number of partitions* and the *same number of elements in each partition* (e.g. one was made through a map on the other).
 
 Parameters:
 
 other - (undocumented)
 
 evidence$10 - (undocumented)
 
 Returns:
 
 (undocumented)
 - zipPartitions
```
public <B,V> RDD<V> zipPartitions(RDD rdd2,
 boolean preservesPartitioning,
 scala.Function2<scala.collection.Iterator<T>,scala.collection.Iterator,scala.collection.Iterator<V>> f,
 scala.reflect.ClassTag evidence$11,
 scala.reflect.ClassTag<V> evidence$12)
```
 Zip this RDD's partitions with one (or more) RDD(s) and return a new RDD by applying a function to the zipped partitions. Assumes that all the RDDs have the *same number of partitions*, but does *not* require them to have the same number of elements in each partition.
 
 Parameters:
 
 rdd2 - (undocumented)
 
 preservesPartitioning - (undocumented)
 
 f - (undocumented)
 
 evidence$11 - (undocumented)
 
 evidence$12 - (undocumented)
 
 Returns:
 
 (undocumented)
 - zipPartitions
```
public <B,V> RDD<V> zipPartitions(RDD rdd2,
 scala.Function2<scala.collection.Iterator<T>,scala.collection.Iterator,scala.collection.Iterator<V>> f,
 scala.reflect.ClassTag evidence$13,
 scala.reflect.ClassTag<V> evidence$14)
```
 - zipPartitions
```
public <B,C,V> RDD<V> zipPartitions(RDD rdd2,
 RDD<C> rdd3,
 boolean preservesPartitioning,
 scala.Function3<scala.collection.Iterator<T>,scala.collection.Iterator,scala.collection.Iterator<C>,scala.collection.Iterator<V>> f,
 scala.reflect.ClassTag evidence$15,
 scala.reflect.ClassTag<C> evidence$16,
 scala.reflect.ClassTag<V> evidence$17)
```
 - zipPartitions
```
public <B,C,V> RDD<V> zipPartitions(RDD rdd2,
 RDD<C> rdd3,
 scala.Function3<scala.collection.Iterator<T>,scala.collection.Iterator,scala.collection.Iterator<C>,scala.collection.Iterator<V>> f,
 scala.reflect.ClassTag evidence$18,
 scala.reflect.ClassTag<C> evidence$19,
 scala.reflect.ClassTag<V> evidence$20)
```
 - zipPartitions
```
public <B,C,D,V> RDD<V> zipPartitions(RDD rdd2,
 RDD<C> rdd3,
 RDD<D> rdd4,
 boolean preservesPartitioning,
 scala.Function4<scala.collection.Iterator<T>,scala.collection.Iterator,scala.collection.Iterator<C>,scala.collection.Iterator<D>,scala.collection.Iterator<V>> f,
 scala.reflect.ClassTag evidence$21,
 scala.reflect.ClassTag<C> evidence$22,
 scala.reflect.ClassTag<D> evidence$23,
 scala.reflect.ClassTag<V> evidence$24)
```
 - zipPartitions
```
public <B,C,D,V> RDD<V> zipPartitions(RDD rdd2,
 RDD<C> rdd3,
 RDD<D> rdd4,
 scala.Function4<scala.collection.Iterator<T>,scala.collection.Iterator,scala.collection.Iterator<C>,scala.collection.Iterator<D>,scala.collection.Iterator<V>> f,
 scala.reflect.ClassTag evidence$25,
 scala.reflect.ClassTag<C> evidence$26,
 scala.reflect.ClassTag<D> evidence$27,
 scala.reflect.ClassTag<V> evidence$28)
```
 - foreach
```
public void foreach(scala.Function1<T,scala.runtime.BoxedUnit> f)
```
 Applies a function f to all elements of this RDD.
 
 Parameters:
 
 f - (undocumented)
 - foreachPartition
```
public void foreachPartition(scala.Function1<scala.collection.Iterator<T>,scala.runtime.BoxedUnit> f)
```
 Applies a function f to each partition of this RDD.
 
 Parameters:
 
 f - (undocumented)
 - collect
```
public Object collect()
```
 Return an array that contains all of the elements in this RDD.
 
 Returns:
 
 (undocumented)
 
 Note:
 
 This method should only be used if the resulting array is expected to be small, as all the data is loaded into the driver's memory.
 - toLocalIterator
```
public scala.collection.Iterator<T> toLocalIterator()
```
 Return an iterator that contains all of the elements in this RDD.
 The iterator will consume as much memory as the largest partition in this RDD.
 
 Returns:
 
 (undocumented)
 
 Note:
 
 This results in multiple Spark jobs, and if the input RDD is the result of a wide transformation (e.g. join with different partitioners), to avoid recomputing the input RDD should be cached first.
 - collect
```
public  RDD collect(scala.PartialFunction<T,U> f,
 scala.reflect.ClassTag evidence$29)
```
 Return an RDD that contains all matching values by applying f.
 
 Parameters:
 
 f - (undocumented)
 
 evidence$29 - (undocumented)
 
 Returns:
 
 (undocumented)
 - subtract
```
public RDD<T> subtract(RDD<T> other)
```
 Return an RDD with the elements from this that are not in other.
 Uses this partitioner/partition size, because even if other is huge, the resulting RDD will be <= us.
 
 Parameters:
 
 other - (undocumented)
 
 Returns:
 
 (undocumented)
 - subtract
```
public RDD<T> subtract(RDD<T> other,
 int numPartitions)
```
 Return an RDD with the elements from this that are not in other.
 
 Parameters:
 
 other - (undocumented)
 
 numPartitions - (undocumented)
 
 Returns:
 
 (undocumented)
 - subtract
```
public RDD<T> subtract(RDD<T> other,
 Partitioner p,
 scala.math.Ordering<T> ord)
```
 Return an RDD with the elements from this that are not in other.
 
 Parameters:
 
 other - (undocumented)
 
 p - (undocumented)
 
 ord - (undocumented)
 
 Returns:
 
 (undocumented)
 - reduce
```
public T reduce(scala.Function2<T,T,T> f)
```
 Reduces the elements of this RDD using the specified commutative and associative binary operator.
 
 Parameters:
 
 f - (undocumented)
 
 Returns:
 
 (undocumented)
 - treeReduce
```
public T treeReduce(scala.Function2<T,T,T> f,
 int depth)
```
 Reduces the elements of this RDD in a multi-level tree pattern.
 
 Parameters:
 
 depth - suggested depth of the tree (default: 2)
 
 f - (undocumented)
 
 Returns:
 
 (undocumented)
 
 See Also:
 
 reduce(scala.Function2<T, T, T>)
 - fold
```
public T fold(T zeroValue,
 scala.Function2<T,T,T> op)
```
 Aggregate the elements of each partition, and then the results for all the partitions, using a given associative function and a neutral "zero value". The function op(t1, t2) is allowed to modify t1 and return it as its result value to avoid object allocation; however, it should not modify t2.
 This behaves somewhat differently from fold operations implemented for non-distributed collections in functional languages like Scala. This fold operation may be applied to partitions individually, and then fold those results into the final result, rather than apply the fold to each element sequentially in some defined ordering. For functions that are not commutative, the result may differ from that of a fold applied to a non-distributed collection.
 
 Parameters:
 
 zeroValue - the initial value for the accumulated result of each partition for the op operator, and also the initial value for the combine results from different partitions for the op operator - this will typically be the neutral element (e.g. Nil for list concatenation or 0 for summation)
 
 op - an operator used to both accumulate results within a partition and combine results from different partitions
 
 Returns:
 
 (undocumented)
 - aggregate
```
public  U aggregate(U zeroValue,
 scala.Function2<U,T,U> seqOp,
 scala.Function2<U,U,U> combOp,
 scala.reflect.ClassTag evidence$30)
```
 Aggregate the elements of each partition, and then the results for all the partitions, using given combine functions and a neutral "zero value". This function can return a different result type, U, than the type of this RDD, T. Thus, we need one operation for merging a T into an U and one operation for merging two U's, as in scala.TraversableOnce. Both of these functions are allowed to modify and return their first argument instead of creating a new U to avoid memory allocation.
 
 Parameters:
 
 zeroValue - the initial value for the accumulated result of each partition for the seqOp operator, and also the initial value for the combine results from different partitions for the combOp operator - this will typically be the neutral element (e.g. Nil for list concatenation or 0 for summation)
 
 seqOp - an operator used to accumulate results within a partition
 
 combOp - an associative operator used to combine results from different partitions
 
 evidence$30 - (undocumented)
 
 Returns:
 
 (undocumented)
 - treeAggregate
```
public  U treeAggregate(U zeroValue,
 scala.Function2<U,T,U> seqOp,
 scala.Function2<U,U,U> combOp,
 int depth,
 scala.reflect.ClassTag evidence$31)
```
 Aggregates the elements of this RDD in a multi-level tree pattern.
 
 Parameters:
 
 depth - suggested depth of the tree (default: 2)
 
 zeroValue - (undocumented)
 
 seqOp - (undocumented)
 
 combOp - (undocumented)
 
 evidence$31 - (undocumented)
 
 Returns:
 
 (undocumented)
 
 See Also:
 
 aggregate(U, scala.Function2<U, T, U>, scala.Function2<U, U, U>, scala.reflect.ClassTag)
 - count
```
public long count()
```
 Return the number of elements in the RDD.
 
 Returns:
 
 (undocumented)
 - countApprox
```
public PartialResult<BoundedDouble> countApprox(long timeout,
 double confidence)
```
 Approximate version of count() that returns a potentially incomplete result within a timeout, even if not all tasks have finished.
 The confidence is the probability that the error bounds of the result will contain the true value. That is, if countApprox were called repeatedly with confidence 0.9, we would expect 90% of the results to contain the true count. The confidence must be in the range [0,1] or an exception will be thrown.
 
 Parameters:
 
 timeout - maximum time to wait for the job, in milliseconds
 
 confidence - the desired statistical confidence in the result
 
 Returns:
 
 a potentially incomplete result, with error bounds
 - countByValue
```
public scala.collection.Map<T,Object> countByValue(scala.math.Ordering<T> ord)
```
 Return the count of each unique value in this RDD as a local map of (value, count) pairs.
 Parameters:
 
 ord - (undocumented)
 
 Returns:
 
 (undocumented)
 
 Note:
 This method should only be used if the resulting map is expected to be small, as the whole thing is loaded into the driver's memory. To handle very large results, consider using
 
 rdd.map(x => (x, 1L)).reduceByKey(_ + _)
 
 , which returns an RDD[T, Long] instead of a map.
 - countByValueApprox
```
public PartialResult<scala.collection.Map<T,BoundedDouble>> countByValueApprox(long timeout,
 double confidence,
 scala.math.Ordering<T> ord)
```
 Approximate version of countByValue().
 
 Parameters:
 
 timeout - maximum time to wait for the job, in milliseconds
 
 confidence - the desired statistical confidence in the result
 
 ord - (undocumented)
 
 Returns:
 
 a potentially incomplete result, with error bounds
 - countApproxDistinct
```
public long countApproxDistinct(int p,
 int sp)
```
 Return approximate number of distinct elements in the RDD.
 The algorithm used is based on streamlib's implementation of "HyperLogLog in Practice: Algorithmic Engineering of a State of The Art Cardinality Estimation Algorithm", available here.
 The relative accuracy is approximately 1.054 / sqrt(2^p). Setting a nonzero (sp is greater than p) would trigger sparse representation of registers, which may reduce the memory consumption and increase accuracy when the cardinality is small.
 
 Parameters:
 
 p - The precision value for the normal set. p must be a value between 4 and sp if sp is not zero (32 max).
 
 sp - The precision value for the sparse set, between 0 and 32. If sp equals 0, the sparse representation is skipped.
 
 Returns:
 
 (undocumented)
 - countApproxDistinct
```
public long countApproxDistinct(double relativeSD)
```
 Return approximate number of distinct elements in the RDD.
 The algorithm used is based on streamlib's implementation of "HyperLogLog in Practice: Algorithmic Engineering of a State of The Art Cardinality Estimation Algorithm", available here.
 
 Parameters:
 
 relativeSD - Relative accuracy. Smaller values create counters that require more space. It must be greater than 0.000017.
 
 Returns:
 
 (undocumented)
 - zipWithIndex
```
public RDD<scala.Tuple2<T,Object>> zipWithIndex()
```
 Zips this RDD with its element indices. The ordering is first based on the partition index and then the ordering of items within each partition. So the first item in the first partition gets index 0, and the last item in the last partition receives the largest index.
 This is similar to Scala's zipWithIndex but it uses Long instead of Int as the index type. This method needs to trigger a spark job when this RDD contains more than one partitions.
 
 Returns:
 
 (undocumented)
 
 Note:
 
 Some RDDs, such as those returned by groupBy(), do not guarantee order of elements in a partition. The index assigned to each element is therefore not guaranteed, and may even change if the RDD is reevaluated. If a fixed ordering is required to guarantee the same index assignments, you should sort the RDD with sortByKey() or save it to a file.
 - zipWithUniqueId
```
public RDD<scala.Tuple2<T,Object>> zipWithUniqueId()
```
 Zips this RDD with generated unique Long ids. Items in the kth partition will get ids k, n+k, 2*n+k, ..., where n is the number of partitions. So there may exist gaps, but this method won't trigger a spark job, which is different from zipWithIndex().
 
 Returns:
 
 (undocumented)
 
 Note:
 
 Some RDDs, such as those returned by groupBy(), do not guarantee order of elements in a partition. The unique ID assigned to each element is therefore not guaranteed, and may even change if the RDD is reevaluated. If a fixed ordering is required to guarantee the same index assignments, you should sort the RDD with sortByKey() or save it to a file.
 - take
```
public Object take(int num)
```
 Take the first num elements of the RDD. It works by first scanning one partition, and use the results from that partition to estimate the number of additional partitions needed to satisfy the limit.
 
 Parameters:
 
 num - (undocumented)
 
 Returns:
 
 (undocumented)
 
 Note:
 
 This method should only be used if the resulting array is expected to be small, as all the data is loaded into the driver's memory.
 , Due to complications in the internal implementation, this method will raise an exception if called on an RDD of Nothing or Null.
 - first
```
public T first()
```
 Return the first element in this RDD.
 
 Returns:
 
 (undocumented)
 - top
```
public Object top(int num,
 scala.math.Ordering<T> ord)
```
 Returns the top k (largest) elements from this RDD as defined by the specified implicit Ordering[T] and maintains the ordering. This does the opposite of takeOrdered. For example:
```
 sc.parallelize(Seq(10, 4, 2, 12, 3)).top(1)
 // returns Array(12)

 sc.parallelize(Seq(2, 3, 4, 5, 6)).top(2)
 // returns Array(6, 5)
 
```
 Parameters:
 
 num - k, the number of top elements to return
 
 ord - the implicit ordering for T
 
 Returns:
 
 an array of top elements
 
 Note:
 
 This method should only be used if the resulting array is expected to be small, as all the data is loaded into the driver's memory.
 - takeOrdered
```
public Object takeOrdered(int num,
 scala.math.Ordering<T> ord)
```
 Returns the first k (smallest) elements from this RDD as defined by the specified implicit Ordering[T] and maintains the ordering. This does the opposite of top. For example:
```
 sc.parallelize(Seq(10, 4, 2, 12, 3)).takeOrdered(1)
 // returns Array(2)

 sc.parallelize(Seq(2, 3, 4, 5, 6)).takeOrdered(2)
 // returns Array(2, 3)
 
```
 Parameters:
 
 num - k, the number of elements to return
 
 ord - the implicit ordering for T
 
 Returns:
 
 an array of top elements
 
 Note:
 
 This method should only be used if the resulting array is expected to be small, as all the data is loaded into the driver's memory.
 - max
```
public T max(scala.math.Ordering<T> ord)
```
 Returns the max of this RDD as defined by the implicit Ordering[T].
 
 Parameters:
 
 ord - (undocumented)
 
 Returns:
 
 the maximum element of the RDD
 - min
```
public T min(scala.math.Ordering<T> ord)
```
 Returns the min of this RDD as defined by the implicit Ordering[T].
 
 Parameters:
 
 ord - (undocumented)
 
 Returns:
 
 the minimum element of the RDD
 - isEmpty
```
public boolean isEmpty()
```
 Returns:
 
 true if and only if the RDD contains no elements at all. Note that an RDD may be empty even when it has at least 1 partition.
 
 Note:
 
 Due to complications in the internal implementation, this method will raise an exception if called on an RDD of Nothing or Null. This may be come up in practice because, for example, the type of parallelize(Seq()) is RDD[Nothing]. (parallelize(Seq()) should be avoided anyway in favor of parallelize(Seq[T]()).)
 - saveAsTextFile
```
public void saveAsTextFile(String path)
```
 Save this RDD as a text file, using string representations of elements.
 
 Parameters:
 
 path - (undocumented)
 - saveAsTextFile
```
public void saveAsTextFile(String path,
 Class<? extends org.apache.hadoop.io.compress.CompressionCodec> codec)
```
 Save this RDD as a compressed text file, using string representations of elements.
 
 Parameters:
 
 path - (undocumented)
 
 codec - (undocumented)
 - saveAsObjectFile
```
public void saveAsObjectFile(String path)
```
 Save this RDD as a SequenceFile of serialized objects.
 
 Parameters:
 
 path - (undocumented)
 - keyBy
```
public <K> RDD<scala.Tuple2<K,T>> keyBy(scala.Function1<T,K> f)
```
 Creates tuples of the elements in this RDD by applying f.
 
 Parameters:
 
 f - (undocumented)
 
 Returns:
 
 (undocumented)
 - checkpoint
```
public void checkpoint()
```
 Mark this RDD for checkpointing. It will be saved to a file inside the checkpoint directory set with SparkContext#setCheckpointDir and all references to its parent RDDs will be removed. This function must be called before any job has been executed on this RDD. It is strongly recommended that this RDD is persisted in memory, otherwise saving it on a file will require recomputation.
 - localCheckpoint
```
public RDD<T> localCheckpoint()
```
 Mark this RDD for local checkpointing using Spark's existing caching layer.
 This method is for users who wish to truncate RDD lineages while skipping the expensive step of replicating the materialized data in a reliable distributed file system. This is useful for RDDs with long lineages that need to be truncated periodically (e.g. GraphX).
 Local checkpointing sacrifices fault-tolerance for performance. In particular, checkpointed data is written to ephemeral local storage in the executors instead of to a reliable, fault-tolerant storage. The effect is that if an executor fails during the computation, the checkpointed data may no longer be accessible, causing an irrecoverable job failure.
 This is NOT safe to use with dynamic allocation, which removes executors along with their cached blocks. If you must use both features, you are advised to set spark.dynamicAllocation.cachedExecutorIdleTimeout to a high value.
 The checkpoint directory set through SparkContext#setCheckpointDir is not used.
 
 Returns:
 
 (undocumented)
 - isCheckpointed
```
public boolean isCheckpointed()
```
 Return whether this RDD is checkpointed and materialized, either reliably or locally.
 
 Returns:
 
 (undocumented)
 - getCheckpointFile
```
public scala.Option<String> getCheckpointFile()
```
 Gets the name of the directory to which this RDD was checkpointed. This is not defined if the RDD is checkpointed locally.
 
 Returns:
 
 (undocumented)
 - context
```
public SparkContext context()
```
 The SparkContext that this RDD was created on.
 - toDebugString
```
public String toDebugString()
```
 A description of this RDD and its recursive dependencies for debugging.
 - toString
```
public String toString()
```
 Overrides:
 
 toString in class Object
 - toJavaRDD
```
public JavaRDD<T> toJavaRDD()
```

Class RDD<T>

Constructor Summary

Method Summary

Methods inherited from class Object

Methods inherited from interface org.apache.spark.internal.Logging

Constructor Detail

RDD

RDD

Method Detail

rddToPairRDDFunctions

rddToAsyncRDDActions

rddToSequenceFileRDDFunctions

rddToOrderedRDDFunctions

doubleRDDToDoubleRDDFunctions

numericRDDToDoubleRDDFunctions

compute

partitioner

sparkContext

id

name

setName

persist

persist

cache

unpersist

getStorageLevel

dependencies

partitions

getNumPartitions

preferredLocations

iterator

map

flatMap

filter

distinct

distinct

repartition

coalesce

sample

randomSplit

takeSample

union

sortBy

intersection

intersection

intersection

glom

cartesian

groupBy

groupBy

groupBy

pipe

pipe

pipe

mapPartitions

mapPartitionsWithIndex

zip

zipPartitions

zipPartitions

zipPartitions

zipPartitions

zipPartitions

zipPartitions

foreach

foreachPartition

collect

toLocalIterator

collect

subtract

subtract

subtract

reduce

treeReduce

fold

aggregate

treeAggregate

count

countApprox

countByValue

countByValueApprox