HyperLogLog API

The HyperLogLog class provides functionality for cardinality estimation and similarity measurements using HyperLogLog sketches. This class supports operations such as updating, merging, and comparing sketches.

C++ Interface

HyperLogLog(int np)

Constructs a HyperLogLog object with the specified precision.

Parameters:

  • np (int): The number of bits used for precision. (2^{np}) is the size of the sketch.

void update(char *seq)

Updates the HyperLogLog sketch with a given sequence.

Parameters:

  • seq (char**): A pointer to the sequence for updating the sketch.

HyperLogLog merge(const HyperLogLog &other) const

Merges the current sketch with another HyperLogLog sketch.

Parameters:

  • other (const HyperLogLog&): The other HyperLogLog object to merge with.

Returns:

  • HyperLogLog: A new HyperLogLog object resulting from the merge.

void printSketch()

Prints the content of the HyperLogLog sketch for debugging purposes.

double distance(const HyperLogLog &h2) const

Computes the distance between two HyperLogLog sketches. The distance is defined as (1.0 - text{Jaccard index}).

Parameters:

  • h2 (const HyperLogLog&): The other HyperLogLog object to compare.

Returns:

  • double: The distance score.

double jaccard_index(const HyperLogLog &h2) const

Computes the Jaccard index between two HyperLogLog sketches.

Parameters:

  • h2 (const HyperLogLog&): The other HyperLogLog object to compare.

Returns:

  • double: The Jaccard index.

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Python Interface

class HyperLogLog(np: int = 10)

Represents the Python interface for the HyperLogLog sketch.

Parameters:

  • np (int): The number of bits used for precision. Default is 10, resulting in a sketch size of (2^{10}).

update(seq: str)

Updates the HyperLogLog sketch with a given sequence.

Parameters:

  • seq (str): The sequence to update the sketch.

merge(other: HyperLogLog) → HyperLogLog

Merges the current sketch with another HyperLogLog sketch.

Parameters:

  • other (HyperLogLog): The other HyperLogLog object to merge with.

Returns:

  • HyperLogLog: A new HyperLogLog object resulting from the merge.

jaccard(other: HyperLogLog) → float

Computes the Jaccard index between two HyperLogLog sketches.

Parameters:

  • other (HyperLogLog): The other HyperLogLog object to compare.

Returns:

  • float: The Jaccard index.

distance(other: HyperLogLog) → float

Computes the distance between two HyperLogLog sketches. The distance is defined as (1.0 - text{Jaccard index}).

Parameters:

  • other (HyperLogLog): The other HyperLogLog object to compare.

Returns:

  • float: The distance score.