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Aggregate (Apache Crunch 0.3.0-incubating API)

org.apache.crunch.lib
Class Aggregate

java.lang.Object
  extended by org.apache.crunch.lib.Aggregate

public class Aggregate
extends Object

Methods for performing various types of aggregations over PCollection instances.


Nested Class Summary
static class Aggregate.PairValueComparator<K,V>
           
static class Aggregate.TopKCombineFn<K,V>
           
static class Aggregate.TopKFn<K,V>
           
 
Constructor Summary
Aggregate()
           
 
Method Summary
static
<K,V> PTable<K,Collection<V>>
collectValues(PTable<K,V> collect)
           
static
<S> PTable<S,Long>
count(PCollection<S> collect)
          Returns a PTable that contains the unique elements of this collection mapped to a count of their occurrences.
static
<S> PCollection<S>
max(PCollection<S> collect)
          Returns the largest numerical element from the input collection.
static
<S> PCollection<S>
min(PCollection<S> collect)
          Returns the smallest numerical element from the input collection.
static
<K,V> PTable<K,V>
top(PTable<K,V> ptable, int limit, boolean maximize)
           
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Aggregate

public Aggregate()
Method Detail

count

public static <S> PTable<S,Long> count(PCollection<S> collect)
Returns a PTable that contains the unique elements of this collection mapped to a count of their occurrences.


top

public static <K,V> PTable<K,V> top(PTable<K,V> ptable,
                                    int limit,
                                    boolean maximize)

max

public static <S> PCollection<S> max(PCollection<S> collect)
Returns the largest numerical element from the input collection.


min

public static <S> PCollection<S> min(PCollection<S> collect)
Returns the smallest numerical element from the input collection.


collectValues

public static <K,V> PTable<K,Collection<V>> collectValues(PTable<K,V> collect)


Copyright © 2012 The Apache Software Foundation. All Rights Reserved.