bloom-filter-ts

Bloom Filter in Typescript

The goal would be to provide users an extendable sdk to create and manipulate bloom filters

This package uses decimal.js to handle precision arithmetic

Usage

There are multiple ways you can create the bloom filter according to your requirements.

Using the helper functions

1. getKandM(n: number, permittedError: Decimal): {k: number, m: number}

   k: number of hashing functions

   m: bitCount

   Use this if you know n and permittedError

   Javascript/Typescript:

   const { k, m } = getKandM(12, new Decimal("0.001"));

2. getK(m: number, n: number): number

   k: number of hashing functions

   Use this if you know m and n

   Javascript/Typescript:

   const k = getK(256, 12);

3. getError(k: number, m: number: n: number): Decimal

   error: % of false positives returned

   Use this to check if your k, m, n values are OK

   Javascript/Typescript:

   const error = getError(14, 256, 12);

4. generateHashingFunction<Type>() : HashingFunction

   The hashing function returned works on the murmur algorithm

   It is recommended to bring other algorithms as well to improve robustness

   Javascript:

   const hashingFunction = generateHashingFunction();

   Typescript:

   // the function takes a generic value type - as long as String(Type) // supports the type you're passing in, it will work
   const hashingFunction = generateHashingFunction<string>();

5. generateBloomFilter<Type>(n: number, permittedError: Decimal, step: number = 1): BloomFilter<Type>

   Use this when you have n and permittedError

   Javascript:

   const bf = generateBloomFilter(25, new Decimal("0.0001"));

   Typescript:

   const bf = generateBloomFilter<string>(25, new Decimal("0.001"));

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Note: For more detailed documentation - checkout the docs/ directory

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