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185 lines
5.6 KiB
185 lines
5.6 KiB
# string-similarity
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Finds degree of similarity between two strings, based on [Dice's Coefficient](http://en.wikipedia.org/wiki/S%C3%B8rensen%E2%80%93Dice_coefficient), which is mostly better than [Levenshtein distance](http://en.wikipedia.org/wiki/Levenshtein_distance).
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## Table of Contents
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- [string-similarity](#string-similarity)
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- [Table of Contents](#table-of-contents)
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- [Usage](#usage)
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- [For Node.js](#for-nodejs)
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- [For browser apps](#for-browser-apps)
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- [API](#api)
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- [compareTwoStrings(string1, string2)](#comparetwostringsstring1-string2)
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- [Arguments](#arguments)
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- [Returns](#returns)
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- [Examples](#examples)
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- [findBestMatch(mainString, targetStrings)](#findbestmatchmainstring-targetstrings)
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- [Arguments](#arguments-1)
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- [Returns](#returns-1)
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- [Examples](#examples-1)
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- [Release Notes](#release-notes)
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- [2.0.0](#200)
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- [3.0.0](#300)
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- [3.0.1](#301)
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- [4.0.1](#401)
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- [4.0.2](#402)
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- [4.0.3](#403)
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## Usage
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#### For Node.js
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Install using:
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```shell
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npm install string-similarity --save
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```
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In your code:
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```javascript
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var stringSimilarity = require("string-similarity");
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var similarity = stringSimilarity.compareTwoStrings("healed", "sealed");
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var matches = stringSimilarity.findBestMatch("healed", [
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"edward",
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"sealed",
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"theatre",
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]);
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```
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#### For browser apps
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Include `<script src="//unpkg.com/string-similarity/umd/string-similarity.min.js"></script>` to get the latest version.
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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.
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This exposes a global variable called `stringSimilarity` which you can start using.
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```
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<script>
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stringSimilarity.compareTwoStrings('what!', 'who?');
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</script>
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```
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(The package is exposed as UMD, so you can consume it as such)
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## API
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The package contains two methods:
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### compareTwoStrings(string1, string2)
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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.
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##### Arguments
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1. string1 (string): The first string
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2. string2 (string): The second string
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Order does not make a difference.
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##### Returns
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(number): A fraction from 0 to 1, both inclusive. Higher number indicates more similarity.
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##### Examples
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```javascript
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stringSimilarity.compareTwoStrings("healed", "sealed");
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// → 0.8
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stringSimilarity.compareTwoStrings(
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"Olive-green table for sale, in extremely good condition.",
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"For sale: table in very good condition, olive green in colour."
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);
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// → 0.6060606060606061
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stringSimilarity.compareTwoStrings(
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"Olive-green table for sale, in extremely good condition.",
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"For sale: green Subaru Impreza, 210,000 miles"
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);
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// → 0.2558139534883721
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stringSimilarity.compareTwoStrings(
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"Olive-green table for sale, in extremely good condition.",
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"Wanted: mountain bike with at least 21 gears."
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);
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// → 0.1411764705882353
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```
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### findBestMatch(mainString, targetStrings)
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Compares `mainString` against each string in `targetStrings`.
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##### Arguments
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1. mainString (string): The string to match each target string against.
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2. targetStrings (Array): Each string in this array will be matched against the main string.
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##### Returns
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(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.
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##### Examples
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```javascript
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stringSimilarity.findBestMatch('Olive-green table for sale, in extremely good condition.', [
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'For sale: green Subaru Impreza, 210,000 miles',
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'For sale: table in very good condition, olive green in colour.',
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'Wanted: mountain bike with at least 21 gears.'
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]);
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// →
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{ ratings:
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[ { target: 'For sale: green Subaru Impreza, 210,000 miles',
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rating: 0.2558139534883721 },
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{ target: 'For sale: table in very good condition, olive green in colour.',
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rating: 0.6060606060606061 },
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{ target: 'Wanted: mountain bike with at least 21 gears.',
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rating: 0.1411764705882353 } ],
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bestMatch:
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{ target: 'For sale: table in very good condition, olive green in colour.',
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rating: 0.6060606060606061 },
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bestMatchIndex: 1
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}
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```
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## Release Notes
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### 2.0.0
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- Removed production dependencies
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- Updated to ES6 (this breaks backward-compatibility for pre-ES6 apps)
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### 3.0.0
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- Performance improvement for `compareTwoStrings(..)`: now O(n) instead of O(n^2)
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- 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
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- Adding a `bestMatchIndex` to the results for `findBestMatch(..)` to point to the best match in the supplied `targetStrings` array
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### 3.0.1
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- Refactoring: removed unused functions; used `substring` instead of `substr`
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- Updated dependencies
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### 4.0.1
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- Distributing as an UMD build to be used in browsers.
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### 4.0.2
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- Update dependencies to latest versions.
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### 4.0.3
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- Make compatible with IE and ES5. Also, update deps. (see [PR56](https://github.com/aceakash/string-similarity/pull/56))
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### 4.0.4
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- Simplify some conditional statements. Also, update deps. (see [PR50](https://github.com/aceakash/string-similarity/pull/50))
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[](https://snyk.io/test/github/aceakash/string-similarity)
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