graph

GraphJS

GraphJS is a simple Javascript library for manipulating directed and undirected graphs.

Your graphs may have self edges, weighted edges, and directed edges, but not multiedges.

Usage

Creating, reading, updating, and deleting edges (CRUD)

var g = new Graph();

g.set('a', 'b', 3); # creates edge (a, b) with weight 3
g.get('a', 'b'); # returns 3

g.set('a', 'b', 4); # changes (a, b) weight to 4
g.get('a', 'b'); # returns 4

g.del('a', 'b'); # removes edge (a, b)
g.get('a', 'b'); # returns undefined

Constructing graphs from data

new Graph({
  a: ['b', 'c'],
  c: ['d'],
}); # triangle with vertices a, b, and c

new Graph({
  a: {b: 2},
  b: {c: 3},
}); # path with vertices a, b, c and weights (a, b) = 2, (b, c) = 3

With directed edges

new Graph({a: ['-b', '-c']}); # Directed edges to b and c.

Degree, size, order, and adjacency

var g = new Graph({
  a: ['b'],
  b: ['c'],
}); # path with vertices a, b, c

g.degree('a'); # returns 1
g.degree('b'); # returns 2
g.degree('c'); # returns 1

g.size(); # returns 2, the number of edges

g.order(); # returns 3, the number of vertices

for (v in g.adj('b')) {
  # v = a, c (in no particular order)
}

Creating directed edges

var g = new Graph();
g.dir('a', 'b'); # a ~ b, but b !~ a
g.has('a', 'b'); # true
g.has('b', 'a'); # false

Alternative syntax

g.set('a', '-b'); # Same as g.dir('a', 'b');

Deleting directed edges

var g = new Graph();
g.set('a', 'b'); # a ~ b, and b ~ a
g.deldir('b', 'a'); # remove b ~ a
g.has('a', 'b'); # true
g.has('b', 'a'); # false

Copying

var g = new Graph({
  a: ['b', 'c'],
  c: ['d'],
});

var h = g.copy(); # an independent copy of g

Directed edges and graph size

You may mix directed and undirected edges in the same graph.

A pair of directed edges (a, b) and (b, a) is always collapsed into an undirected edge. An undirected edge (a, b) may be expanded into a directed edge (a, b) by deleting the directed edge (b, a) with deldir(b, a).

For consistency, the size of a graph is defined to be the number of undirected edges plus the number of directed edges. In other words, two distinct directed edges between two distinct vertices do not count twice for the size.

A directed self edge is indistinguishable from an undirected self edge.

Tests

GraphJS is packaged with nodeunit tests.

The easiest way to run the tests is with npm test.

$ npm test
...
OK: 173 assertions (23ms)

You can also test your browser by loading the test.html page.