https://github.com/ceejbot/farmfilter

https://github.com/ceejbot/farmfilter

Last synced: 16 days ago
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• Host: GitHub
• URL: https://github.com/ceejbot/farmfilter
• Owner: ceejbot
• License: other
• Created: 2017-10-19T18:20:31.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2018-06-10T19:17:31.000Z (about 8 years ago)
• Last Synced: 2026-05-30T18:28:13.351Z (about 1 month ago)
• Language: JavaScript
• Size: 92.8 KB
• Stars: 2
• Watchers: 0
• Forks: 0
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
Yet another Bloom filter implementation for node.js. Everybody has to write one, as you know. Backed by FarmHash.

To install: `npm install farmfilter`

[![on npm](https://img.shields.io/npm/v/farmfilter.svg?style=flat)](https://www.npmjs.com/package/farmfilter) [![Build Status](http://img.shields.io/travis/ceejbot/xx-bloom/master.svg?style=flat)](https://travis-ci.org/ceejbot/farmfilter) [![Coverage Status](https://coveralls.io/repos/github/ceejbot/farmfilter/badge.svg?branch=master)](https://coveralls.io/github/ceejbot/farmfilter?branch=master)

## Usage

To create a filter, pass an options hash to the constructor:

```javascript

const Filter = require('farmfilter');

const options =

{

	bits: 1024,

	hashes: 7,

	seeds: [1, 2, 3, 4, 5, 6, 7]

};

const filter = new BloomFilter(options);

```

You can pass in seeds for the hash functions if you like, or they'll be randomly generated. Seeds must be integers.

You may also pass in a buffer as generated by `filter.toBuffer()`.

### createOptimal()

To create a filter optimized for the number of items you'll be storing and a desired error rate:

`filter = Filter.createOptimal(estimatedItemCount, errorRate);`

The error rate parameter is optional. It defaults to 0.005, or a 0.5% rate. This is probably the constructor you want to use.

### add()

`filter.add('cat');`

Adds the given item to the filter. Can also accept buffers and arrays containing strings or buffers:

`filter.add(['cat', 'dog', 'coati', 'red panda']);`

### has()

To test for membership:

`filter.has('dog');`

### clear()

To clear the filter:

`filter.clear();`

### toBuffer()

Returns a buffer with seeds and filter data.

### fromBuffer()

Reconstitutes a filter from a freeze-dried buffer.

## Licence

ISC.