io.cdap.wrangler.sampling

Class Poisson<T>

java.lang.Object

io.cdap.wrangler.sampling.Sampler<T>

io.cdap.wrangler.sampling.Poisson<T>

Type Parameters:

T - The type of sample.

public class Poisson<T>
extends Sampler<T>

A sampler implementation based on the Poisson Distribution. While sampling elements with fraction and replacement, the selected number of each element follows a given poisson distribution.

See Also:

https://en.wikipedia.org/wiki/Poisson_distribution, Gap Sampling

Field Summary

Fields inherited from class io.cdap.wrangler.sampling.Sampler

emptyIterable, EPSILON

Constructor Summary

Constructors

Constructor and Description
Poisson(double fraction) Create a poisson sampler which can sample elements with replacement.
Poisson(double fraction, long seed) Create a poisson sampler which can sample elements with replacement.

Method Summary

Modifier and Type	Method and Description
Iterator<T>	sample(Iterator<T> input) Sample the input elements, for each input element, generate its count following a poisson distribution.

Methods inherited from class java.lang.Object

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

Constructor Detail

Poisson

public Poisson(double fraction,
               long seed)

Create a poisson sampler which can sample elements with replacement.

Parameters:

fraction - The expected count of each element.

seed - Random number generator seed for internal PoissonDistribution.

Poisson

public Poisson(double fraction)

Create a poisson sampler which can sample elements with replacement.

Parameters:

fraction - The expected count of each element.

Method Detail

sample

public Iterator<T> sample(Iterator<T> input)

Sample the input elements, for each input element, generate its count following a poisson distribution.

Specified by:

sample in class Sampler<T>

Parameters:

input - Elements to be sampled.

Returns:

The sampled result which is lazy computed upon input elements.