bellman-ford

bellman-ford allows you to run the bellman ford algorithm in node.js.

It is written in C++ and ported to node.js. It uses a directed graph
as it's underlying data structure.

Install

npm install bellman-ford

Examples

$3

``js
var graph = new bellman-ford();
`

$3

`js
graph.add_node("a");
graph.add_node("b");
graph.add_node("c");
graph.add_node("d");
graph.add_node("e");
`

$3

`js
graph.add_edge("a", "b", -0.1);
graph.add_edge("b", "a", 0.2);
graph.add_edge("a", "c", 0.9);
graph.add_edge("c", "e", -0.1);
graph.add_edge("e", "c", 0.2);
graph.add_edge("e", "d", 0.2);
graph.add_edge("d", "e", 0.1);
graph.add_edge("d", "a", 0.4);
graph.add_edge("b", "d", 0.3);
`

$3

`js
console.log(graph.bellmanford("c"));
`
which will output

`js
[ [ 'a', '0.5' ],
[ 'b', '0.4' ],
[ 'd', '0.1' ],
[ 'e', '-0.1' ],
[ 'c', '0' ] ]
`

where each subarray contains a value in the graph say a and
the distance to the source node c whcich in this case is 0.5

Functions

$3

This function adds a node to directed graph.
It takes one parameter add_node(node_name)
If a node with node_name already exists then nothing wil happen

$3

This function adds edges to directed graph.
It takes three parameters 'add_edge(node_from, node_to, edge_weight)'
If node_from or node_to has not yet beed added to the graph then
the function call will fail

$3

This function updates edge weights between nodes
It takes three parameters 'update_edge(node_from, node_to, edge_weight)'

$3

This function prints out the current graph

`js
graph.print();
`
for the given example will output
`
a:
weight: -0.1 to: b
weight: 0.9 to: c
b:
weight: 0.2 to: a
weight: 0.3 to: d
d:
weight: 0.1 to: e
weight: 0.4 to: a
e:
weight: 0.2 to: c
weight: 0.2 to: d
c:
weight: -0.1 to: e
`

$3

This function removes all nodes with less then two edges as well
as removing all associated edges.

$3

This is the main function which will run the bellman ford algorithm on
the current graph. It will return a 2d array of the form
[node_name, distance_from_source]

If the graph contains negative weight cycles then it will return an empty array

Compiling from Source

To compile the code from source you must have python gcc and node-gyp
installed on your machine.

Then run

node-gyp configure

and

node-gyp build`