public abstract class RDD<T> extends Object implements scala.Serializable, Logging
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.
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) |
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$33)
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.
|
scala.Option<org.apache.spark.rdd.RDDCheckpointData<T>> |
checkpointData() |
RDD<T> |
coalesce(int numPartitions,
boolean shuffle,
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$32)
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().
|
org.apache.spark.util.CallSite |
creationSite()
User code that created this RDD (e.g.
|
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.
|
<A> RDD<T> |
filterWith(scala.Function1<Object,A> constructA,
scala.Function2<T,A,Object> p)
Filters this RDD with p, where p takes an additional parameter of type A.
|
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.
|
<A,U> RDD<U> |
flatMapWith(scala.Function1<Object,A> constructA,
boolean preservesPartitioning,
scala.Function2<T,A,scala.collection.Seq<U>> f,
scala.reflect.ClassTag<U> evidence$12)
FlatMaps f over this RDD, where f takes an additional parameter of type A.
|
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 and commutative 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.
|
<A> void |
foreachWith(scala.Function1<Object,A> constructA,
scala.Function2<T,A,scala.runtime.BoxedUnit> f)
Applies f to each element of this RDD, where f takes an additional parameter of type A.
|
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> |
mapPartitionsWithContext(scala.Function2<TaskContext,scala.collection.Iterator<T>,scala.collection.Iterator<U>> f,
boolean preservesPartitioning,
scala.reflect.ClassTag<U> evidence$9)
:: DeveloperApi ::
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$8)
Return a new RDD by applying a function to each partition of this RDD, while tracking the index
of the original partition.
|
<U> RDD<U> |
mapPartitionsWithSplit(scala.Function2<Object,scala.collection.Iterator<T>,scala.collection.Iterator<U>> f,
boolean preservesPartitioning,
scala.reflect.ClassTag<U> evidence$10)
Return a new RDD by applying a function to each partition of this RDD, while tracking the index
of the original partition.
|
<A,U> RDD<U> |
mapWith(scala.Function1<Object,A> constructA,
boolean preservesPartitioning,
scala.Function2<T,A,U> f,
scala.reflect.ClassTag<U> evidence$11)
Maps f over this RDD, where f takes an additional parameter of type A.
|
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)
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$37) |
static <K,V> OrderedRDDFunctions<K,V,scala.Tuple2<K,V>> |
rddToOrderedRDDFunctions(RDD<scala.Tuple2<K,V>> rdd,
scala.math.Ordering<K> evidence$38,
scala.reflect.ClassTag<K> evidence$39,
scala.reflect.ClassTag<V> evidence$40) |
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,
|
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.
|
scala.Option<org.apache.spark.rdd.RDDOperationScope> |
scope()
The scope associated with the operation that created this RDD.
|
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
|
Object |
toArray()
Return an array that contains all of the elements in this RDD.
|
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) |
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$34)
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$13)
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$14,
scala.reflect.ClassTag<V> evidence$15)
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$16,
scala.reflect.ClassTag<V> evidence$17) |
<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$18,
scala.reflect.ClassTag<C> evidence$19,
scala.reflect.ClassTag<V> evidence$20) |
<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$21,
scala.reflect.ClassTag<C> evidence$22,
scala.reflect.ClassTag<V> evidence$23) |
<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$24,
scala.reflect.ClassTag<C> evidence$25,
scala.reflect.ClassTag<D> evidence$26,
scala.reflect.ClassTag<V> evidence$27) |
<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$28,
scala.reflect.ClassTag<C> evidence$29,
scala.reflect.ClassTag<D> evidence$30,
scala.reflect.ClassTag<V> evidence$31) |
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.
|
initializeIfNecessary, initializeLogging, isTraceEnabled, log_, log, logDebug, logDebug, logError, logError, logInfo, logInfo, logName, logTrace, logTrace, logWarning, logWarning
public RDD(SparkContext _sc, scala.collection.Seq<Dependency<?>> deps, scala.reflect.ClassTag<T> evidence$1)
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)
public static <T> AsyncRDDActions<T> rddToAsyncRDDActions(RDD<T> rdd, scala.reflect.ClassTag<T> evidence$37)
public static <K,V> SequenceFileRDDFunctions<K,V> rddToSequenceFileRDDFunctions(RDD<scala.Tuple2<K,V>> rdd, scala.reflect.ClassTag<K> kt, scala.reflect.ClassTag<V> vt,keyWritableFactory, valueWritableFactory)
public static <K,V> OrderedRDDFunctions<K,V,scala.Tuple2<K,V>> rddToOrderedRDDFunctions(RDD<scala.Tuple2<K,V>> rdd, scala.math.Ordering<K> evidence$38, scala.reflect.ClassTag<K> evidence$39, scala.reflect.ClassTag<V> evidence$40)
public static DoubleRDDFunctions doubleRDDToDoubleRDDFunctions(RDD<Object> rdd)
public static <T> DoubleRDDFunctions numericRDDToDoubleRDDFunctions(RDD<T> rdd, scala.math.Numeric<T> num)
public abstract scala.collection.Iterator<T> compute(Partition split, TaskContext context)
split
- (undocumented)context
- (undocumented)public scala.Option<Partitioner> partitioner()
public SparkContext sparkContext()
public int id()
public String name()
public RDD<T> persist(StorageLevel newLevel)
newLevel
- (undocumented)public RDD<T> unpersist(boolean blocking)
blocking
- Whether to block until all blocks are deleted.public StorageLevel getStorageLevel()
public final scala.collection.Seq<Dependency<?>> dependencies()
public final Partition[] partitions()
public final int getNumPartitions()
public final scala.collection.Seq<String> preferredLocations(Partition split)
split
- (undocumented)public final scala.collection.Iterator<T> iterator(Partition split, TaskContext context)
split
- (undocumented)context
- (undocumented)public <U> RDD<U> map(scala.Function1<T,U> f, scala.reflect.ClassTag<U> evidence$3)
f
- (undocumented)evidence$3
- (undocumented)public <U> RDD<U> flatMap(scala.Function1<T,scala.collection.TraversableOnce<U>> f, scala.reflect.ClassTag<U> evidence$4)
f
- (undocumented)evidence$4
- (undocumented)public RDD<T> filter(scala.Function1<T,Object> f)
f
- (undocumented)public RDD<T> distinct(int numPartitions, scala.math.Ordering<T> ord)
numPartitions
- (undocumented)ord
- (undocumented)public RDD<T> distinct()
public RDD<T> repartition(int numPartitions, scala.math.Ordering<T> ord)
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.
numPartitions
- (undocumented)ord
- (undocumented)public RDD<T> coalesce(int numPartitions, boolean shuffle, scala.math.Ordering<T> ord)
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.
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).
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.
numPartitions
- (undocumented)shuffle
- (undocumented)ord
- (undocumented)public RDD<T> sample(boolean withReplacement, double fraction, long seed)
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 >= 0seed
- seed for the random number generatorpublic RDD<T>[] randomSplit(double[] weights, long seed)
weights
- weights for splits, will be normalized if they don't sum to 1seed
- random seed
public Object takeSample(boolean withReplacement, int num, long seed)
withReplacement
- whether sampling is done with replacementnum
- size of the returned sampleseed
- seed for the random number generatorpublic RDD<T> union(RDD<T> other)
.distinct()
to eliminate them).other
- (undocumented)public <K> RDD<T> sortBy(scala.Function1<T,K> f, boolean ascending, int numPartitions, scala.math.Ordering<K> ord, scala.reflect.ClassTag<K> ctag)
f
- (undocumented)ascending
- (undocumented)numPartitions
- (undocumented)ord
- (undocumented)ctag
- (undocumented)public RDD<T> intersection(RDD<T> other)
Note that this method performs a shuffle internally.
other
- (undocumented)public RDD<T> intersection(RDD<T> other, Partitioner partitioner, scala.math.Ordering<T> ord)
Note that this method performs a shuffle internally.
partitioner
- Partitioner to use for the resulting RDDother
- (undocumented)ord
- (undocumented)public RDD<T> intersection(RDD<T> other, int numPartitions)
Note that this method performs a shuffle internally.
numPartitions
- How many partitions to use in the resulting RDDother
- (undocumented)public RDD<Object> glom()
public <U> RDD<scala.Tuple2<T,U>> cartesian(RDD<U> other, scala.reflect.ClassTag<U> evidence$5)
this
and b is in other
.other
- (undocumented)evidence$5
- (undocumented)public <K> RDD<scala.Tuple2<K,scala.collection.Iterable<T>>> groupBy(scala.Function1<T,K> f, scala.reflect.ClassTag<K> kt)
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.
f
- (undocumented)kt
- (undocumented)public <K> RDD<scala.Tuple2<K,scala.collection.Iterable<T>>> groupBy(scala.Function1<T,K> f, int numPartitions, scala.reflect.ClassTag<K> kt)
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.
f
- (undocumented)numPartitions
- (undocumented)kt
- (undocumented)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)
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.
f
- (undocumented)p
- (undocumented)kt
- (undocumented)ord
- (undocumented)public RDD<String> pipe(String command)
command
- (undocumented)public RDD<String> pipe(String command, scala.collection.Map<String,String> env)
command
- (undocumented)env
- (undocumented)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)
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.public <U> RDD<U> mapPartitions(scala.Function1<scala.collection.Iterator<T>,scala.collection.Iterator<U>> f, boolean preservesPartitioning, scala.reflect.ClassTag<U> evidence$6)
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.
f
- (undocumented)preservesPartitioning
- (undocumented)evidence$6
- (undocumented)public <U> RDD<U> mapPartitionsWithIndex(scala.Function2<Object,scala.collection.Iterator<T>,scala.collection.Iterator<U>> f, boolean preservesPartitioning, scala.reflect.ClassTag<U> evidence$8)
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.
f
- (undocumented)preservesPartitioning
- (undocumented)evidence$8
- (undocumented)public <U> RDD<U> mapPartitionsWithContext(scala.Function2<TaskContext,scala.collection.Iterator<T>,scala.collection.Iterator<U>> f, boolean preservesPartitioning, scala.reflect.ClassTag<U> evidence$9)
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.
f
- (undocumented)preservesPartitioning
- (undocumented)evidence$9
- (undocumented)public <U> RDD<U> mapPartitionsWithSplit(scala.Function2<Object,scala.collection.Iterator<T>,scala.collection.Iterator<U>> f, boolean preservesPartitioning, scala.reflect.ClassTag<U> evidence$10)
f
- (undocumented)preservesPartitioning
- (undocumented)evidence$10
- (undocumented)public <A,U> RDD<U> mapWith(scala.Function1<Object,A> constructA, boolean preservesPartitioning, scala.Function2<T,A,U> f, scala.reflect.ClassTag<U> evidence$11)
constructA
- (undocumented)preservesPartitioning
- (undocumented)f
- (undocumented)evidence$11
- (undocumented)public <A,U> RDD<U> flatMapWith(scala.Function1<Object,A> constructA, boolean preservesPartitioning, scala.Function2<T,A,scala.collection.Seq<U>> f, scala.reflect.ClassTag<U> evidence$12)
constructA
- (undocumented)preservesPartitioning
- (undocumented)f
- (undocumented)evidence$12
- (undocumented)public <A> void foreachWith(scala.Function1<Object,A> constructA, scala.Function2<T,A,scala.runtime.BoxedUnit> f)
constructA
- (undocumented)f
- (undocumented)public <A> RDD<T> filterWith(scala.Function1<Object,A> constructA, scala.Function2<T,A,Object> p)
constructA
- (undocumented)p
- (undocumented)public <U> RDD<scala.Tuple2<T,U>> zip(RDD<U> other, scala.reflect.ClassTag<U> evidence$13)
other
- (undocumented)evidence$13
- (undocumented)public <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$14, scala.reflect.ClassTag<V> evidence$15)
rdd2
- (undocumented)preservesPartitioning
- (undocumented)f
- (undocumented)evidence$14
- (undocumented)evidence$15
- (undocumented)public <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$16, scala.reflect.ClassTag<V> evidence$17)
public <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$18, scala.reflect.ClassTag<C> evidence$19, scala.reflect.ClassTag<V> evidence$20)
public <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$21, scala.reflect.ClassTag<C> evidence$22, scala.reflect.ClassTag<V> evidence$23)
public <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$24, scala.reflect.ClassTag<C> evidence$25, scala.reflect.ClassTag<D> evidence$26, scala.reflect.ClassTag<V> evidence$27)
public <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$28, scala.reflect.ClassTag<C> evidence$29, scala.reflect.ClassTag<D> evidence$30, scala.reflect.ClassTag<V> evidence$31)
public void foreach(scala.Function1<T,scala.runtime.BoxedUnit> f)
f
- (undocumented)public void foreachPartition(scala.Function1<scala.collection.Iterator<T>,scala.runtime.BoxedUnit> f)
f
- (undocumented)public Object collect()
public scala.collection.Iterator<T> toLocalIterator()
The iterator will consume as much memory as the largest partition in this RDD.
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.
public Object toArray()
public <U> RDD<U> collect(scala.PartialFunction<T,U> f, scala.reflect.ClassTag<U> evidence$32)
f
.f
- (undocumented)evidence$32
- (undocumented)public RDD<T> subtract(RDD<T> other)
this
that are not in other
.
Uses this
partitioner/partition size, because even if other
is huge, the resulting
RDD will be <= us.
other
- (undocumented)public RDD<T> subtract(RDD<T> other, int numPartitions)
this
that are not in other
.other
- (undocumented)numPartitions
- (undocumented)public RDD<T> subtract(RDD<T> other, Partitioner p, scala.math.Ordering<T> ord)
this
that are not in other
.other
- (undocumented)p
- (undocumented)ord
- (undocumented)public T reduce(scala.Function2<T,T,T> f)
f
- (undocumented)public T treeReduce(scala.Function2<T,T,T> f, int depth)
depth
- suggested depth of the tree (default: 2)f
- (undocumented)reduce(scala.Function2<T, T, T>)
public T fold(T zeroValue, scala.Function2<T,T,T> op)
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.
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 partitionspublic <U> U aggregate(U zeroValue, scala.Function2<U,T,U> seqOp, scala.Function2<U,U,U> combOp, scala.reflect.ClassTag<U> evidence$33)
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 partitioncombOp
- an associative operator used to combine results from different partitionsevidence$33
- (undocumented)public <U> U treeAggregate(U zeroValue, scala.Function2<U,T,U> seqOp, scala.Function2<U,U,U> combOp, int depth, scala.reflect.ClassTag<U> evidence$34)
depth
- suggested depth of the tree (default: 2)zeroValue
- (undocumented)seqOp
- (undocumented)combOp
- (undocumented)evidence$34
- (undocumented)aggregate(U, scala.Function2<U, T, U>, scala.Function2<U, U, U>, scala.reflect.ClassTag<U>)
public long count()
public PartialResult<BoundedDouble> countApprox(long timeout, double confidence)
timeout
- (undocumented)confidence
- (undocumented)public scala.collection.Map<T,Object> countByValue(scala.math.Ordering<T> ord)
Note that 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.
ord
- (undocumented)public PartialResult<scala.collection.Map<T,BoundedDouble>> countByValueApprox(long timeout, double confidence, scala.math.Ordering<T> ord)
timeout
- (undocumented)confidence
- (undocumented)ord
- (undocumented)public long countApproxDistinct(int p, int sp)
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 > p
would trigger sparse representation of registers, which may reduce the memory consumption
and increase accuracy when the cardinality is small.
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.public long countApproxDistinct(double relativeSD)
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.
relativeSD
- Relative accuracy. Smaller values create counters that require more space.
It must be greater than 0.000017.public RDD<scala.Tuple2<T,Object>> zipWithIndex()
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.
Note that 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.
public RDD<scala.Tuple2<T,Object>> zipWithUniqueId()
zipWithIndex()
.
Note that 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.
public Object take(int num)
num
- (undocumented)public T first()
public Object top(int num, scala.math.Ordering<T> ord)
public Object takeOrdered(int num, scala.math.Ordering<T> ord)
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)
num
- k, the number of elements to returnord
- the implicit ordering for Tpublic T max(scala.math.Ordering<T> ord)
ord
- (undocumented)public T min(scala.math.Ordering<T> ord)
ord
- (undocumented)public boolean isEmpty()
public void saveAsTextFile(String path)
path
- (undocumented)public void saveAsTextFile(String path, Class<? extends org.apache.hadoop.io.compress.CompressionCodec> codec)
path
- (undocumented)codec
- (undocumented)public void saveAsObjectFile(String path)
path
- (undocumented)public <K> RDD<scala.Tuple2<K,T>> keyBy(scala.Function1<T,K> f)
f
.f
- (undocumented)public void checkpoint()
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.public RDD<T> localCheckpoint()
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.
public boolean isCheckpointed()
public scala.Option<String> getCheckpointFile()
public org.apache.spark.util.CallSite creationSite()
public scala.Option<org.apache.spark.rdd.RDDOperationScope> scope()
This is more flexible than the call site and can be defined hierarchically. For more detail, see the documentation of {{RDDOperationScope}}. This scope is not defined if the user instantiates this RDD himself without using any Spark operations.
public scala.Option<org.apache.spark.rdd.RDDCheckpointData<T>> checkpointData()
public SparkContext context()
SparkContext
that this RDD was created on.public String toDebugString()
public String toString()
toString
in class Object