HyperLogLogEstimator (searchlib 7.501.17 API)

java.lang.Object
- com.yahoo.searchlib.aggregation.hll.HyperLogLogEstimator

All Implemented Interfaces:

UniqueCountEstimator<Sketch<?>>
```
public class HyperLogLogEstimator
extends Object
implements UniqueCountEstimator<Sketch<?>>
```
Implementation of the result computation phase of the HyperLogLog algorithm. Based on the pseudo code from: http://www.dmtcs.org/dmtcs-ojs/index.php/proceedings/article/viewArticle/914

Author:

bjorncs

Constructor Summary

Constructors
Constructor	Description
`HyperLogLogEstimator()`	Creates the estimator with the default precision (`HyperLogLog.DEFAULT_PRECISION`.
`HyperLogLogEstimator(int precision)`	Creates the estimator for a given precision.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type Method Description

long estimateCount(Sketch<?> sketch)
Estimates the number of unique elements.
- Methods inherited from class java.lang.Object
  clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - HyperLogLogEstimator
```
public HyperLogLogEstimator(int precision)
```
    Creates the estimator for a given precision. The resulting memory consumption is the exponential to the precision.
    
    Parameters:
    
    precision - The precision parameter as defined in HLL algorithm.
  - HyperLogLogEstimator
```
public HyperLogLogEstimator()
```
    Creates the estimator with the default precision (HyperLogLog.DEFAULT_PRECISION.
- Method Detail
  - estimateCount
```
public long estimateCount(Sketch<?> sketch)
```
    Estimates the number of unique elements.
    
    Specified by:
    
    estimateCount in interface UniqueCountEstimator<Sketch<?>>
    
    Parameters:
    
    sketch - A sketch populated with values from the aggregation phase of HLL.
    
    Returns:
    
    The estimated number of unique elements.