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HyperLogLog-based set cardinality estimation library
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HyperLogLog-based set cardinality estimation library

This library estimates the number of unique elements in a set, in a quick and memory-efficient manner. It's based on the following:

  1. Flajolet et al., "HyperLogLog: the analysis of a near-optimal cardinality estimation algorithm", DMTCS proc. AH 2007,
  2. Heule, Nunkesser and Hall 2013, "HyperLogLog in Practice: Algorithmic Engineering of a State of The Art Cardinality Estimation Algorithm",

The accuracy/memory usage are user-selectable. Typically, a cardinality estimator will give a perfect estimate of small cardinalities (up to 100 unique elements), and 97% accuracy or better (usually much better) for any cardinality up to near 2^64, while consuming several KB of memory (no more than 16KB).


Usage is very simple:

ICardinalityEstimator<string> estimator = new CardinalityEstimator();

estimator.Add("George Michael");

ulong numberOfuniqueElements = estimator.Count(); // will be 3

Nuget Package

This code is available as the Nuget package CardinalityEstimation. To install, run the following command in the Package Manager Console:

Install-Package CardinalityEstimation

Keeping things friendly

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact with any additional questions or comments.

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