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1# fastest-levenshtein :rocket:
2> Fastest JS/TS implemenation of [Levenshtein distance](https://en.wikipedia.org/wiki/Levenshtein_distance).<br>
3> Measure the difference between two strings.
4
5[![Build Status](https://travis-ci.org/ka-weihe/fastest-levenshtein.svg?branch=master)](https://travis-ci.org/ka-weihe/fastest-levenshtein)
6[![Coverage Status](https://coveralls.io/repos/github/ka-weihe/node-levenshtein/badge.svg?branch=master)](https://coveralls.io/github/ka-weihe/node-levenshtein?branch=master)
7[![Language grade: JavaScript](https://img.shields.io/lgtm/grade/javascript/g/ka-weihe/fastest-levenshtein.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/ka-weihe/fastest-levenshtein/context:javascript)
8![npm](https://img.shields.io/npm/dm/fastest-levenshtein)
9```bash
10$ npm i fastest-levenshtein
11```
12
13## Usage
14### Node
15```javascript
16const {distance, closest} = require('fastest-levenshtein')
17
18// Print levenshtein-distance between 'fast' and 'faster'
19console.log(distance('fast', 'faster'))
20//=> 2
21
22// Print string from array with lowest edit-distance to 'fast'
23console.log(closest('fast', ['slow', 'faster', 'fastest']))
24//=> 'faster'
25```
26
27### Deno
28```javascript
29import {distance, closest} from 'https://deno.land/x/fastest_levenshtein/mod.ts'
30
31// Print levenshtein-distance between 'fast' and 'faster'
32console.log(distance('fast', 'faster'))
33//=> 2
34
35// Print string from array with lowest edit-distance to 'fast'
36console.log(closest('fast', ['slow', 'faster', 'fastest']))
37//=> 'faster'
38```
39
40## Benchmark
41I generated 500 pairs of strings with length N. I measured the ops/sec each library achieves to process all the given pairs. Higher is better.
42
43| Test Target | N=4 | N=8 | N=16 | N=32 | N=64 | N=128 | N=256 | N=512 | N=1024 |
44|---------------------------|-------|-------|-------|------|-------|-------|-------|-------|--------|
45| fastest-levenshtein | 44423 | 23702 | 10764 | 4595 | 1049 | 291.5 | 86.64 | 22.24 | 5.473 |
46| js-levenshtein | 21261 | 10030 | 2939 | 824 | 223 | 57.62 | 14.77 | 3.717 | 0.934 |
47| leven | 19688 | 6884 | 1606 | 436 | 117 | 30.34 | 7.604 | 1.929 | 0.478 |
48| fast-levenshtein | 18577 | 6112 | 1265 | 345 | 89.41 | 22.70 | 5.676 | 1.428 | 0.348 |
49| levenshtein-edit-distance | 22968 | 7445 | 1493 | 409 | 109 | 28.07 | 7.095 | 1.789 | 0.445 |
50
51### Relative Performance
52This image shows the relative performance between `fastest-levenshtein` and `js-levenshtein` (the 2nd fastest). `fastest-levenshtein` is always a lot faster. y-axis shows "times faster".
53
54![Benchmark](/images/relaperf.png)
55
56## License
57This project is licensed under the MIT License - see the [LICENSE.md](LICENSE.md) file for details