D3 NLP Visualizer Update

A couple years ago I put together a simple NLP parse tree visualizer demo which used d3 and the dagre layout library.  At the time, integrating dagre with d3 required a bit of manual work (or copy-paste); however, since then dagre-d3 library was split out of dagre which added an easy API for adding and removing nodes.  Even though the library isn’t under active development, I think it’s still the most powerful pure-JS directed graph layout library out there.

An example from the wiki shows how simple the the dagre-d3 API is for creating directed graphs, abbreviated here:

    // Create the input graph
    var g = new dagreD3.graphlib.Graph()
      .setDefaultEdgeLabel(function() { return {}; });

    // Here we"re setting nodeclass, which is used by our custom drawNodes function
    // below.
    g.setNode(0,  { label: "TOP", class: "type-TOP" });

    // ... snip

    // Set up edges, no special attributes.
    g.setEdge(3, 4);
    // ... snip
    // Create the renderer
    var render = new dagreD3.render();

    var svg = d3.select("svg"),
        svgGroup = svg.append("g");

    // Run the renderer. This is what draws the final graph.
    render(d3.select("svg g"), g);

Since that original demo site still gets a fair amount of traffic, I thought it would be good to update it to use dagre-d3 instead of the original hand-rolled bindings (along with other cleanup).  You can see the change set required here.

The other goal was to re-familiarize myself with d3 and dagre, since I have a couple projects in mind which would make heavy use of both.  Hopefully I’ll have something to post here in the next couple months.

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