org.apache.flink.api.java.sampling

类 ReservoirSamplerWithReplacement<T>

java.lang.Object

org.apache.flink.api.java.sampling.RandomSampler<T>

org.apache.flink.api.java.sampling.DistributedRandomSampler<T>

org.apache.flink.api.java.sampling.ReservoirSamplerWithReplacement<T>

类型参数:

T - The type of sample.

@Internal
public class ReservoirSamplerWithReplacement<T>
extends DistributedRandomSampler<T>

A simple in memory implementation of Reservoir Sampling with replacement and with only one pass through the input iteration whose size is unpredictable. The basic idea behind this sampler implementation is quite similar to ReservoirSamplerWithoutReplacement. The main difference is that, in the first phase, we generate weights for each element K times, so that each element can get selected multiple times.

This implementation refers to the algorithm described in "Optimal Random Sampling from Distributed Streams Revisited".

字段概要

从类继承的字段 org.apache.flink.api.java.sampling.DistributedRandomSampler

emptyIntermediateIterable, numSamples

从类继承的字段 org.apache.flink.api.java.sampling.RandomSampler

emptyIterable, EPSILON

构造器概要

构造器

构造器和说明
ReservoirSamplerWithReplacement(int numSamples) Create a sampler with fixed sample size and default random number generator.
ReservoirSamplerWithReplacement(int numSamples, long seed) Create a sampler with fixed sample size and random number generator seed.
ReservoirSamplerWithReplacement(int numSamples, Random random) Create a sampler with fixed sample size and random number generator.

方法概要

限定符和类型	方法和说明
Iterator<IntermediateSampleData<T>>	sampleInPartition(Iterator<T> input) Sample algorithm for the first phase.

从类继承的方法 org.apache.flink.api.java.sampling.DistributedRandomSampler

sample, sampleInCoordinator

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

构造器详细资料

ReservoirSamplerWithReplacement

public ReservoirSamplerWithReplacement(int numSamples)

Create a sampler with fixed sample size and default random number generator.

参数:

numSamples - Number of selected elements, must be non-negative.

ReservoirSamplerWithReplacement

public ReservoirSamplerWithReplacement(int numSamples,
                                       long seed)

Create a sampler with fixed sample size and random number generator seed.

参数:

numSamples - Number of selected elements, must be non-negative.

seed - Random number generator seed

ReservoirSamplerWithReplacement

public ReservoirSamplerWithReplacement(int numSamples,
                                       Random random)

Create a sampler with fixed sample size and random number generator.

参数:

numSamples - Number of selected elements, must be non-negative.

random - Random number generator

方法详细资料

sampleInPartition

public Iterator<IntermediateSampleData<T>> sampleInPartition(Iterator<T> input)

从类复制的说明: DistributedRandomSampler

Sample algorithm for the first phase. It operates on a single partition.

指定者:

sampleInPartition 在类中 DistributedRandomSampler<T>

参数:

input - The DataSet input of each partition.

返回:

Intermediate sample output which will be used as the input of the second phase.