Nautical Poseidon Mythology

    ngraph.graph
    TypeScript icon, indicating that this package has built-in type declarations

    19.1.0 • Public • Published

    ngraph.graph

    Graph data structure for javascript. This library belongs to a family of javascript graph packages called ngraph.

    build status

    Creating a graph

    Create a graph with no edges and no nodes:

    var createGraph = require('ngraph.graph');
    var g = createGraph();

    Growing a graph

    The graph g can be grown in two ways. You can add one node at a time:

    g.addNode('hello');
    g.addNode('world');

    Now graph g contains two nodes: hello and world. You can also use addLink() method to grow a graph. Calling this method with nodes which are not present in the graph creates them:

    g.addLink('space', 'bar'); // now graph 'g' has two new nodes: 'space' and 'bar'

    If nodes already present in the graph 'addLink()' makes them connected:

    // Only a link between 'hello' and 'world' is created. No new nodes.
    g.addLink('hello', 'world');

    What to use as nodes and edges?

    The most common and convenient choices are numbers and strings. You can associate arbitrary data with node via optional second argument of addNode() method:

    // Node 'world' is associated with a string object 'custom data'
    g.addNode('world', 'custom data');
     
    // You can associate arbitrary objects with node:
    g.addNode('server', {
      status: 'on',
      ip: '127.0.0.1'
    });
     
    // to get data back use `data` property of node:
    var server = g.getNode('server');
    console.log(server.data); // prints associated object

    You can also associate arbitrary object with a link using third optional argument of addLink() method:

    // A link between nodes '1' and '2' is now associated with object 'x'
    g.addLink(1, 2, x);

    Enumerating nodes and links

    After you created a graph one of the most common things to do is to enumerate its nodes/links to perform an operation.

    g.forEachNode(function(node){
        console.log(node.id, node.data);
    });

    The function takes callback which accepts current node. Node object may contain internal information. node.id and node.data represent parameters passed to the g.addNode(id, data) method and they are guaranteed to be present in future versions of the library.

    To enumerate all links in the graph use forEachLink() method:

    g.forEachLink(function(link) {
        console.dir(link);
    });

    To enumerate all links for a specific node use forEachLinkedNode() method:

    g.forEachLinkedNode('hello', function(linkedNode, link){
        console.log("Connected node: ", linkedNode.id, linkedNode.data);
        console.dir(link); // link object itself
    });

    This method always enumerates both inbound and outbound links. If you want to get only outbound links, pass third optional argument:

    g.forEachLinkedNode('hello',
        function(linkedNode, link) { /* ... */ },
        true // enumerate only outbound links
      );

    To get a particular node object use getNode() method. E.g.:

    var world = g.getNode('world'); // returns 'world' node
    console.log(world.id, world.data);

    To get a particular link object use getLink() method:

    var helloWorldLink = g.getLink('hello', 'world'); // returns a link from 'hello' to 'world'
    console.log(helloWorldLink);

    To remove a node or a link from a graph use removeNode() or removeLink() correspondingly:

    g.removeNode('space');
    // Removing link is a bit harder, since method requires actual link object:
    g.forEachLinkedNode('hello', function(linkedNode, link){
      g.removeLink(link);
    });

    You can also remove all nodes and links by calling

    g.clear();

    Listening to Events

    Whenever someone changes your graph you can listen to notifications:

    g.on('changed', function(changes) {
      console.dir(changes); // prints array of change records
    });
     
    g.add(42); // this will trigger 'changed event'

    Each change record holds information:

    ChangeRecord = {
      changeType: add|remove|update - describes type of this change
      node: - only present when this record reflects a node change, represents actual node
      link: - only present when this record reflects a link change, represents actual link
    }
    

    Sometimes it is desirable to react only on bulk changes. ngraph.graph supports this via beginUpdate()/endUpdate() methods:

    g.beginUpdate();
    for(var i = 0; i < 100; ++i) {
      g.addLink(i, i + 1); // no events are triggered here
    }
    g.endUpdate(); // this triggers all listeners of 'changed' event

    If you want to stop listen to events use off() method:

    g.off('changed', yourHandler); // no longer interested in changes from graph

    For more information about events, please follow to ngraph.events

    Install

    With npm do:

    npm install ngraph.graph
    

    Or download from CDN:

    <script src='https://unpkg.com/ngraph.graph@19.0.0/dist/ngraph.graph.min.js'></script>

    If you download from CDN the library will be available under createGraph global name.

    License

    BSD 3-clause

    Install

    npm i ngraph.graph

    DownloadsWeekly Downloads

    9,818

    Version

    19.1.0

    License

    BSD-3-Clause

    Unpacked Size

    76 kB

    Total Files

    16

    Last publish

    Collaborators

    • anvaka