D3NodeArrows

Basic force directed layout with directional arrows

by basiclaser

HTML

<script src="http://labratrevenge.com/d3-tip/javascripts/d3.tip.v0.6.3.js"></script>
<script type="application/json" id="mis">
    {
        "nodes": [{
            "name": "Gillenormand",
                "group": 3
        }, {
            "name": "Magnon",
                "group": 5
        }, {
            "name": "Mlle.Gillenormand",
                "group": 4
        }, {
            "name": "Mme.Pontmercy",
                "group": 5
        }, {
            "name": "Mlle.Vaubois",
                "group": 5
        }],
            "links": [{
            "source": 1,
                "target": 0,
                "value": 1
        }, {
            "source": 2,
                "target": 0,
                "value": 8
        }, {
            "source": 3,
                "target": 0,
                "value": 10
        }, {
            "source": 3,
                "target": 2,
                "value": 6
        }]
    }
</script>

CSS

.node {
    stroke: #fff;
    stroke-width: 1.5px;
}
.link {
    stroke: #999;
    stroke-opacity: .6;
}

JavaScript

//Constants for the SVG
var width = 500,
    height = 500;

//Set up the colour scale
var color = d3.scale.category20();

//Set up the force layout
var force = d3.layout.force()
    .charge(-1)
    .linkDistance(300)
    .size([width, height]);

//Append a SVG to the body of the html page. Assign this SVG as an object to svg
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);



//Read the data from the mis element 
var mis = document.getElementById('mis').innerHTML;
graph = JSON.parse(mis);

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

//Create all the line svgs but without locations yet
var link = svg.selectAll(".link")
    .data(graph.links)
    .enter().append("line")
    .attr("class", "link")
    .style("marker-end",  "url(#suit)") //Added 
    ;

//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", 8)
    .style("fill", function (d) {
    return color(d.group);
})
    .call(force.drag);
	
  node.append("image")
      .attr("xlink:href", "https://github.com/favicon.ico")
      .attr("x", -8)
      .attr("y", -8)
      .attr("width", 16)
      .attr("height", 16);

  node.append("text")
      .attr("dx", 12)
      .attr("dy", ".35em")
      .text(function(d) { return d.name });

//Now we are giving the SVGs co-ordinates - the force layout is generating the co-ordinates which this code is using to update the attributes of the SVG elements
force.on("tick", function () {
    link.attr("x1", function (d) {
        return d.source.x;
    })
        .attr("y1", function (d) {
        return d.source.y;
    })
        .attr("x2", function (d) {
        return d.target.x;
    })
        .attr("y2", function (d) {
        return d.target.y;
    });

    node.attr("cx", function (d) {
        return d.x;
    })
       ...