string-similarity

Finds degree of similarity between two strings, based on Dice's Coefficient, which is mostly better than Levenshtein distance.

Table of Contents

• Usage
  • For Node.js
  • For browser apps
• API
  • compareTwoStrings(string1, string2)
    • Arguments
    • Returns
    • Examples
  • findBestMatch(mainString, targetStrings)
    • Arguments
    • Returns
    • Examples
• Release Notes
  • 2.0.0
  • 3.0.0
  • 3.0.1
  • 4.0.1

Usage

For Node.js

Install using:

npm install string-similarity --save

In your code:

var stringSimilarity = require('string-similarity');

var similarity = stringSimilarity.compareTwoStrings('healed', 'sealed'); 

var matches = stringSimilarity.findBestMatch('healed', ['edward', 'sealed', 'theatre']);

For browser apps

Include <script src="//unpkg.com/string-similarity/umd/string-similarity.min.js"></script> to get the latest version.

Or <script src="//unpkg.com/string-similarity@4.0.1/umd/string-similarity.min.js"></script> to get a specific version (4.0.1) in this case.

This exposes a global variable called stringSimilarity which you can start using.

<script>
  stringSimilarity.compareTwoStrings('what!', 'who?');
</script>

(The package is exposed as UMD, so you can consume it as such)

API

The package contains two methods:

compareTwoStrings(string1, string2)

Returns a fraction between 0 and 1, which indicates the degree of similarity between the two strings. 0 indicates completely different strings, 1 indicates identical strings. The comparison is case-sensitive.

Arguments

1. string1 (string): The first string
2. string2 (string): The second string

Order does not make a difference.

Returns

(number): A fraction from 0 to 1, both inclusive. Higher number indicates more similarity.

Examples

stringSimilarity.compareTwoStrings('healed', 'sealed');
// → 0.8

stringSimilarity.compareTwoStrings('Olive-green table for sale, in extremely good condition.', 
  'For sale: table in very good  condition, olive green in colour.');
// → 0.6060606060606061

stringSimilarity.compareTwoStrings('Olive-green table for sale, in extremely good condition.', 
  'For sale: green Subaru Impreza, 210,000 miles');
// → 0.2558139534883721

stringSimilarity.compareTwoStrings('Olive-green table for sale, in extremely good condition.', 
  'Wanted: mountain bike with at least 21 gears.');
// → 0.1411764705882353

findBestMatch(mainString, targetStrings)

Compares mainString against each string in targetStrings.

Arguments

1. mainString (string): The string to match each target string against.
2. targetStrings (Array): Each string in this array will be matched against the main string.

Returns

(Object): An object with a ratings property, which gives a similarity rating for each target string, a bestMatch property, which specifies which target string was most similar to the main string, and a bestMatchIndex property, which specifies the index of the bestMatch in the targetStrings array.

Examples

stringSimilarity.findBestMatch('Olive-green table for sale, in extremely good condition.', [
  'For sale: green Subaru Impreza, 210,000 miles', 
  'For sale: table in very good condition, olive green in colour.', 
  'Wanted: mountain bike with at least 21 gears.'
]);
// → 
{ ratings:
   [ { target: 'For sale: green Subaru Impreza, 210,000 miles',
       rating: 0.2558139534883721 },
     { target: 'For sale: table in very good condition, olive green in colour.',
       rating: 0.6060606060606061 },
     { target: 'Wanted: mountain bike with at least 21 gears.',
       rating: 0.1411764705882353 } ],
  bestMatch:
   { target: 'For sale: table in very good condition, olive green in colour.',
     rating: 0.6060606060606061 },
  bestMatchIndex: 1 
}

Release Notes

2.0.0

• Removed production dependencies
• Updated to ES6 (this breaks backward-compatibility for pre-ES6 apps)

3.0.0

• Performance improvement for compareTwoStrings(..): now O(n) instead of O(n^2)
• The algorithm has been tweaked slightly to disregard spaces and word boundaries. This will change the rating values slightly but not enough to make a significant difference
• Adding a bestMatchIndex to the results for findBestMatch(..) to point to the best match in the supplied targetStrings array

3.0.1

• Refactoring: removed unused functions; used substring instead of substr
• Updated dependencies

4.0.1

• Distributing as an UMD build to be used in browsers.