@datastructures-js/graph

Graph & Directed Graph implementation in javascript.

Contents

• Install
• require
• import
• API
  • constructor
  • addVertex
  • hasVertex
  • getVertexValue
  • getVerticesCount
  • addEdge
  • hasEdge
  • getEdgesCount
  • getWeight
  • getConnectedVertices
  • getConnectedEdges
  • removeVertex
  • removeEdge
  • removeEdges
  • traverseDfs
  • traverseBfs
  • clear
• Build
• License

install

npm install --save @datastructures-js/graph

require

const { Graph, DirectedGraph } = require('@datastructures-js/graph');

import

import { Graph, DirectedGraph } from '@datastructures-js/graph';

API

constructor

Creates a new graph

JS

const directedGraph = new DirectedGraph();

const graph = new Graph();

TS

// DirectedGraph<T extends number|string, U = undefined>
const directedGraph = new DirectedGraph<number, { id: string, someProp: any }>();

// Graph<T extends number|string, U = undefined>
const graph = new Graph<string, number>();

addVertex

Adds a vertex to the graph.

directedGraph
  .addVertex('v1', 1)
  .addVertex('v2', 2)
  .addVertex('v3', 3)
  .addVertex('v4', 4)
  .addVertex('v5', 5);

graph
  .addVertex('v1', true)
  .addVertex('v2', true)
  .addVertex('v3', true)
  .addVertex('v4', true)
  .addVertex('v5', true);

hasVertex

Checks if the graph has a vertex by its key.

console.log(directedGraph.hasVertex('v7')); // false
console.log(graph.hasVertex('v1')); // true

getVertexValue

Returns the value associated with a vertex key.

console.log(directedGraph.getVertexValue('v5')); // 5
console.log(graph.getVertexValue('v1')); // true

getVerticesCount

Gets the number of vertices in the graph.

console.log(directedGraph.getVerticesCount()); // 5
console.log(graph.getVerticesCount()); // 5

addEdge

Adds a weighted edge between two existings vertices. Default weight is 1 if not defined. The single edge is a direction from source to destination in a directed graph, and a two-way connection in a graph.

directedGraph
  .addEdge('v1', 'v2', 2)
  .addEdge('v1', 'v3', 3)
  .addEdge('v1', 'v4', 1)
  .addEdge('v2', 'v4', 1)
  .addEdge('v3', 'v5', 2)
  .addEdge('v4', 'v3', 1)
  .addEdge('v4', 'v5', 4);

graph
  .addEdge('v1', 'v2', 2)
  .addEdge('v2', 'v3', 3)
  .addEdge('v1', 'v3', 6)
  .addEdge('v2', 'v4', 1)
  .addEdge('v4', 'v3', 1)
  .addEdge('v4', 'v5', 4)
  .addEdge('v3', 'v5', 2);

hasEdge

Checks if the graph has an edge between two existing vertices. In directed graph, it returns true only if there is a direction from source to destination.

console.log(directedGraph.hasEdge('v1', 'v2')); // true
console.log(directedGraph.hasEdge('v2', 'v1')); // false

console.log(graph.hasEdge('v1', 'v2')); // true
console.log(graph.hasEdge('v2', 'v1')); // true

getEdgesCount

Gets the number of edges in the graph.

console.log(directedGraph.getEdgesCount()); // 7
console.log(graph.getEdgesCount()); // 7

getWeight

Gets the edge's weight between two vertices. If there is no direct edge between the two vertices, it returns Infinity. It also returns 0 if the source key is equal to destination key.

console.log(directedGraph.getWeight('v1', 'v2')); // 2
console.log(directedGraph.getWeight('v2', 'v1')); // Infinity
console.log(directedGraph.getWeight('v1', 'v1')); // 0

console.log(graph.getWeight('v1', 'v2')); // 2
console.log(graph.getWeight('v2', 'v1')); // 2
console.log(graph.getWeight('v1', 'v1')); // 0
console.log(graph.getWeight('v1', 'v4')); // Infinity

getConnectedVertices

Returns a list of keys of vertices connected to a given vertex.

console.log(directedGraph.getConnectedVertices('v4')); // ['v3', 'v5']
console.log(graph.getConnectedVertices('v1')); // ['v2', 'v3']

getConnectedEdges

Returns an object of keys of vertices connected to a given vertex with the edges weight.

console.log(directedGraph.getConnectedEdges('v4')); // { v3: 1, v5: 4 }
console.log(graph.getConnectedEdges('v1')); // { v2: 2, v3: 6 }

removeVertex

Removes a vertex with all its edges from the graph.

directedGraph.removeVertex('v5');
console.log(directedGraph.getVerticesCount()); // 4
console.log(directedGraph.getEdgesCount()); // 5

graph.removeVertex('v5');
console.log(graph.getVerticesCount()); // 4
console.log(graph.getEdgesCount()); // 5

removeEdge

Removes an edge between two existing vertices

directedGraph.removeEdge('v1', 'v3'); // true
console.log(directedGraph.getEdgesCount()); // 4

graph.removeEdge('v2', 'v3'); // true
console.log(graph.getEdgesCount()); // 4

removeEdges

Removes all connected edges to a vertex and returns the number of removed edges.

const dg = new DirectedGraph()
  .addVertex('v1')
  .addVertex('v2')
  .addVertex('v3')
  .addEdge('v1', 'v2')
  .addEdge('v2', 'v1')
  .addEdge('v1', 'v3')
  .removeEdges('v1'); // 3

const g = new Graph()
  .addVertex('v1')
  .addVertex('v2')
  .addVertex('v3')
  .addEdge('v1', 'v2')
  .addEdge('v1', 'v3')
  .removeEdges('v1'); // 2

traverseDfs

Traverses the graph from a starting vertex using the depth-first recursive search. it also accepts an optional third param as a callback to abort traversal when it returns true.

directedGraph.traverseDfs('v1', (key, value) => console.log(`${key}: ${value}`));
/*
v1: 1
v2: 2
v4: 4
v3: 3
*/

graph.traverseDfs('v1', (key, value) => console.log(`${key}: ${value}`));
/*
v1: true
v2: true
v4: true
v3: true
*/

let counter = 0;
graph.traverseDfs('v1', (key, value) => {
  console.log(`${key}: ${value}`);
  counter += 1;
}, () => counter > 1);
/*
v1: true
v2: true
*/

traverseBfs

Traverses the graph from a starting vertex using the breadth-first search with a queue. it also accepts an optional third param as a callback to abort traversal when it returns true.

directedGraph.traverseBfs('v1', (key, value) => console.log(`${key}: ${value}`));
/*
v1: 1
v2: 2
v4: 4
v3: 3
*/

graph.traverseBfs('v1', (key, value) => console.log(`${key}: ${value}`));
/*
v1: true
v2: true
v3: true
v4: true
*/

let counter = 0;
graph.traverseBfs('v1', (key, value) => {
  console.log(`${key}: ${value}`);
  counter += 1;
}, () => counter > 1);
/*
v1: true
v2: true
*/

clear

Clears all vertices and edges in the graph.

directedGraph.clear();
console.log(directedGraph.getVerticesCount()); // 0
console.log(directedGraph.getEdgesCount()); // 0

graph.clear();
console.log(graph.getVerticesCount()); // 0
console.log(graph.getEdgesCount()); // 0

Build

grunt build

License

The MIT License. Full License is here