D3NodeExamplesPinANode

A mixture of the best parts of the following D3 examples http://bl.ocks.org/mbostock/4062045 http://bl.ocks.org/mbostock/929623 http://bl.ocks.org/Caged/6476579

by Simon Raper

HTML

<script src="http://labratrevenge.com/d3-tip/javascripts/d3.tip.v0.6.3.js"></script>
<script type="application/json" id="mis">
    {
        "nodes": [{
            "name": "Myriel",
                "group": 1
        }, {
            "name": "Napoleon",
                "group": 1
        }, {
            "name": "Mlle.Baptistine",
                "group": 1
        }, {
            "name": "Mme.Magloire",
                "group": 1
        }, {
            "name": "CountessdeLo",
                "group": 1
        }, {
            "name": "Geborand",
                "group": 1
        }, {
            "name": "Champtercier",
                "group": 1
        }, {
            "name": "Cravatte",
                "group": 1
        }, {
            "name": "Count",
                "group": 1
        }, {
            "name": "OldMan",
                "group": 1
        }, {
            "name": "Labarre",
                "group": 2
        }, {
            "name": "Valjean",
                "group": 2
        }, {
            "name": "Marguerite",
                "group": 3
        }, {
            "name": "Mme.deR",
                "group": 2
        }, {
            "name": "Isabeau",
                "group": 2
        }, {
            "name": "Gervais",
                "group": 2
        }, {
            "name": "Tholomyes",
                "group": 3
        }, {
            "name": "Listolier",
                "group": 3
        }, {
            "name": "Fameuil",
                "group": 3
        }, {
            "name": "Blacheville",
                "group": 3
        }, {
            "name": "Favourite",
                "group": 3
        }, {
            "name": "Dahlia",
                "group": 3
        }, {
            "name": "Zephine",
                "group": 3
        }, {
            "name": "Fantine",
                "group": 3
        }, {
            "name": "Mme.Thenardier",
                "group": 4
        }, {
            "name":...

CSS

.node {
    stroke: #fff;
    stroke-width: 1.5px;
}
.link {
    stroke: #999;
    stroke-opacity: .6;
}
.d3-tip {
    line-height: 1;
    color: #999;
}
.cursor {
    fill: none;
    stroke: brown;
    pointer-events: none;
}

JavaScript

var width = 960,
    height = 500;

var color = d3.scale.category20();

var force = d3.layout.force()
    .charge(-120)
    .linkDistance(30)
    .size([width, height]);

//AddCode from http://bl.ocks.org/norrs/2883411
var node_drag = d3.behavior.drag()
        .on("dragstart", dragstart)
        .on("drag", dragmove)
        .on("dragend", dragend);

    function dragstart(d, i) {
        force.stop() // stops the force auto positioning before you start dragging
    }

    function dragmove(d, i) {
        d.px += d3.event.dx;
        d.py += d3.event.dy;
        d.x += d3.event.dx;
        d.y += d3.event.dy; 
    }

    function dragend(d, i) {
        d.fixed = true; // of course set the node to fixed so the force doesn't include the node in its auto positioning stuff
        force.resume();
    }

//AddCode End

var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);

var stuff = document.getElementById('mis').innerHTML;
graph = JSON.parse(stuff);

force.nodes(graph.nodes)  //Creates the graph data structure out of the json data
    .links(graph.links)
    .start();

//Create all the line svgs but without locations yet <line class="link" style="stroke-width: 1px;"></line>

var link = svg.selectAll(".link")
    .data(graph.links)
    .enter().append("line")
    .attr("class", "link")
    .style("stroke-width", function (d) {
    return Math.sqrt(d.value);
});

//Do the same with the circles for the nodes - no 

var node = svg.selectAll(".node")
    .data(graph.nodes)
    .enter().append("circle")
    .attr("class", "node")
    .attr("r", 5)
    .style("fill", function (d) {
    return color(d.group);
})
.call(node_drag); //ChangeCode

//Now we are giving the SVGs co-ordinates - looks like the force layout is generating the co-ordinates which this code is using to up date the attributes of the SVG elements

force.on("tick", function () {
    link.attr("x1", function (d) {
        return d.source.x;
    })
       ...