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174 lines
4.7 KiB
Markdown
174 lines
4.7 KiB
Markdown
# Trie Prefix Tree
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[](https://travis-ci.org/lyndseybrowning/trie-prefix-tree)
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[](https://codecov.io/github/lyndseybrowning/trie-prefix-tree)
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[](http://npm.im/trie-prefix-tree)
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[](http://npm-stat.com/charts.html?package=trie-prefix-tree&from=2015-08-01)
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[](http://opensource.org/licenses/MIT)
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[](https://github.com/semantic-release/semantic-release)
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This is a [Trie](https://en.wikipedia.org/wiki/Trie) implementation written in JavaScript, with insert and remove capability. It can be used to search a predefined dictionary for prefixes, check a prefix exists and retrieve a list of anagrams and sub-anagrams based on given letters.
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## What is a Trie?
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A Trie (also known as a prefix-tree) is a data structure for storing strings in a tree. Each branch in the tree represents a single character which allows for fast and efficient depth-first searching. Let's say we have a dictionary with the words: CAR, CAT and CURL. We can visualise the trie like this:
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## Installation
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Pull down dependencies:
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```
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npm install
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```
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This project uses [Jest](https://facebook.github.io/jest/) for unit testing and [ESLint](http://eslint.org/) for linting.
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To run combined linting & unit tests:
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```
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npm test
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```
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To run linting:
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```
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npm run lint
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```
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Run tests in watch mode:
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```
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npm run test-watch
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```
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Get code coverage report:
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```
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npm run test-coverage
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```
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## How to Use
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To use the Trie, install and save it to your package dependencies:
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```
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npm install trie-prefix-tree --save
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```
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To create a new Trie:
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```javascript
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var trie = require('trie-prefix-tree');
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// using ES2015 Modules
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import trie from 'trie-prefix-tree';
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```
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Instantiate the Trie:
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```javascript
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var myTrie = trie(['cat', 'cats', 'dogs', 'elephant', 'tiger']);
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```
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Trie functionality:
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```javascript
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// retrieve a stringified dump of the Trie object
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myTrie.dump(); // { c: { a: { t: $: 1 }, s: 1 ... }}
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// optionally pass in spacer parameter to format the output string
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myTrie.dump(2); // equivalent of JSON.stringify(obj, null, 2);
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```
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```javascript
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// retrieve the Trie object instance
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myTrie.tree();
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```
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```javascript
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// add a new word to the Trie
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myTrie.addWord('lion');
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```
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```javascript
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// remove an existing word from the Trie
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myTrie.removeWord('dogs');
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```
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Adding and removing words can be chained:
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```javascript
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myTrie.addWord('hello').removeWord('hello');
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```
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Prefix searching:
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```javascript
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// check if a prefix exists:
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myTrie.isPrefix('do'); // true
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myTrie.isPrefix('z'); // false
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```
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```javascript
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// count prefixes
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myTrie.countPrefix('c'); // 2
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```
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```javascript
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// get an array of words with the passed in prefix
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myTrie.getPrefix('c'); // ['cat', 'cats']
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// Pass false as the second parameter to disable
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// output being sorted alphabetically
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// this is useful when your dictionary is already sorted
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// and will therefore save performance
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myTrie.getPrefix('c', false); // ['cat', 'cats']
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```
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```javascript
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// get a random word at a prefix
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myTrie.getRandomWordWithPrefix('c'); // 'cat'
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myTrie.getRandomWordWithPrefix('c'); // 'cats'
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```
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Other:
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```javascript
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// retrieve a full list of words in the Trie
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// the output array is automatically sorted
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myTrie.getWords(); // ['cat', 'cats', 'elephant', 'lion', 'tiger']
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// pass false to disable the output being sorted
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// this is useful when your dictionary is already sorted
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// and will therefore save performance
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myTrie.getWords(false); // ['cat', 'cats', 'elephant', 'tiger', 'lion']
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```
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```javascript
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// check if a word exists in the Trie
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myTrie.hasWord('elephant'); // true
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myTrie.hasWord('zoo'); // false
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```
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```javascript
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// generate a list of valid anagrams from the given letters
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myTrie.getAnagrams('act'); // ['cat'];
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```
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```javascript
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// generate a list of valid sub-anagrams from the given letters
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myTrie.getSubAnagrams('ctalion'); ['cat', 'cats', 'lion'];
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```
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## Credits
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Credit goes to [Kent C. Dodds](https://github.com/kentcdodds) for providing the awesome 'How to Create an Open Source JavaScript Library' course, available on [egghead.io](https://egghead.io/courses/how-to-write-an-open-source-javascript-library).
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## License
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This project is referenced under the MIT license and is free to use and distribute.
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MIT @ Lyndsey Browning
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