FindConnectedNodes

I've adapted the code from this stackoverflow answer (from D3's creator Mike Bostock) so that you can highlight neighbours in a force directed layout. Just doubleclick on a node to fade out any non-immediate neighbours.

by Kearnan Kelly

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 toggle = 0;

var color = d3.scale.category20();

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

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", 10)
    .style("opacity", 1)
    .style("fill", function (d) {
    return color(d.group);
})
    .call(force.drag)
    .on('dblclick', connectedNodes);

//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;
    })
        .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;
    })
        .attr("cy", function (d) {
        return d.y;
    });
});


var linkedByIndex = {};
for (i = 0; i < graph.nodes.length; i++) {
    linkedByIndex[i + "," + i] = 1;
};
graph.links.forEach(function (d) {
    linkedByIndex[d.source.index + "," + d.target.index] = 1;
});



function neighboring(a, b) {
    return...