GerHobbelt/.gitignore

## .gitignore
# Editor backup files
*.bak
*~

## README.md

      
    Raw
  

              README.md
            
          
    Experiment …… ∆ ∞

Derived from the D3.js example force_cluster.html
Usage


Click on node to expand or collapse.
Click on hull (which shows up when you expanded a group node) to collapse the group.
Drag node to move entire graph around.

Notes


network() is the one who takes care of (re)generating the nodes and links from the original data, based on the expand[] info, i.e. which group(s) should be shown in expanded form and which shouldn't.


only group nodes are expected to a .size attribute (read: your own JSON should use that attribute for any node). Same goes for the fields .group_data and .link_count: all of these are expected to be generated by the network() call. (.group_data is a reference to the group (x/y/size/link_count) for a node, group_node.link_count counts the number of links between groups.)


you'll very probably have to tweak .gravity, .charge, .linkDistance and maybe also .linkStrength to make your own graphs look good. Compare the final layout of this graph with the ones produced by the v2.9.6 force_cluster.html D3 code: note the generally quite different position of the groups which have only a single link to other groups; that and other differences are all due to the 4 aforementioned force parameters.


## CREDITS
Code derived from the d3.js 'force' example:

The miserables.json file contains the weighted network of coappearances of
characters in Victor Hugo's novel /Les Miserables/. Nodes represent characters
as indicated by the labels, and edges connect any pair of characters that
appear in the same chapter of the book. The values on the edges are the number
of such coappearances. The data on coappearances were taken from D. E. Knuth,
"The Stanford GraphBase: A Platform for Combinatorial Computing",
Addison-Wesley, Reading, MA (1993).

The group labels were transcribed from "Finding and evaluating community
structure in networks" by M. E. J. Newman and M. Girvan.

## index.html
<!DOCTYPE html>
<html>
  <head>
    <title>Clustered Network</title>
    <script src="http://d3js.org/d3.v2.js"></script>

    <style type="text/css">
svg {
  border: 1px solid #ccc;
}
body {
  font: 10px sans-serif;
}
circle.node {
  fill: lightsteelblue;
  stroke: #555;
  stroke-width: 3px;
}
circle.leaf {
  stroke: #fff;
  stroke-width: 1.5px;
}
path.hull {
  fill: lightsteelblue;
  fill-opacity: 0.3;
}
line.link {
  stroke: #333;
  stroke-opacity: 0.5;
  pointer-events: none;
}
    </style>
  </head>
  <body>
    <script type="text/javascript">
var width = 960,     // svg width
    height = 600,     // svg height
    dr = 4,      // default point radius
    off = 15,    // cluster hull offset
    expand = {}, // expanded clusters
    data, net, force, hullg, hull, linkg, link, nodeg, node;

var curve = d3.svg.line()
    .interpolate("cardinal-closed")
    .tension(.85);

var fill = d3.scale.category20();

function noop() { return false; }

function nodeid(n) {
  return n.size ? "_g_"+n.group : n.name;
}

function linkid(l) {
  var u = nodeid(l.source),
      v = nodeid(l.target);
  return u<v ? u+"|"+v : v+"|"+u;
}

function getGroup(n) { return n.group; }

// constructs the network to visualize
function network(data, prev, index, expand) {
  expand = expand || {};
  var gm = {},    // group map
      nm = {},    // node map
      lm = {},    // link map
      gn = {},    // previous group nodes
      gc = {},    // previous group centroids
      nodes = [], // output nodes
      links = []; // output links

  // process previous nodes for reuse or centroid calculation
  if (prev) {
    prev.nodes.forEach(function(n) {
      var i = index(n), o;
      if (n.size > 0) {
        gn[i] = n;
        n.size = 0;
      } else {
        o = gc[i] || (gc[i] = {x:0,y:0,count:0});
        o.x += n.x;
        o.y += n.y;
        o.count += 1;
      }
    });
  }

  // determine nodes
  for (var k=0; k<data.nodes.length; ++k) {
    var n = data.nodes[k],
        i = index(n),
        l = gm[i] || (gm[i]=gn[i]) || (gm[i]={group:i, size:0, nodes:[]});

    if (expand[i]) {
      // the node should be directly visible
      nm[n.name] = nodes.length;
      nodes.push(n);
      if (gn[i]) {
        // place new nodes at cluster location (plus jitter)
        n.x = gn[i].x + Math.random();
        n.y = gn[i].y + Math.random();
      }
    } else {
      // the node is part of a collapsed cluster
      if (l.size == 0) {
        // if new cluster, add to set and position at centroid of leaf nodes
        nm[i] = nodes.length;
        nodes.push(l);
        if (gc[i]) {
          l.x = gc[i].x / gc[i].count;
          l.y = gc[i].y / gc[i].count;
        }
      }
      l.nodes.push(n);
    }
  // always count group size as we also use it to tweak the force graph strengths/distances
    l.size += 1;
  n.group_data = l;
  }

  for (i in gm) { gm[i].link_count = 0; }

  // determine links
  for (k=0; k<data.links.length; ++k) {
    var e = data.links[k],
        u = index(e.source),
        v = index(e.target);
  if (u != v) {
    gm[u].link_count++;
    gm[v].link_count++;
  }
    u = expand[u] ? nm[e.source.name] : nm[u];
    v = expand[v] ? nm[e.target.name] : nm[v];
    var i = (u<v ? u+"|"+v : v+"|"+u),
        l = lm[i] || (lm[i] = {source:u, target:v, size:0});
    l.size += 1;
  }
  for (i in lm) { links.push(lm[i]); }

  return {nodes: nodes, links: links};
}

function convexHulls(nodes, index, offset) {
  var hulls = {};

  // create point sets
  for (var k=0; k<nodes.length; ++k) {
    var n = nodes[k];
    if (n.size) continue;
    var i = index(n),
        l = hulls[i] || (hulls[i] = []);
    l.push([n.x-offset, n.y-offset]);
    l.push([n.x-offset, n.y+offset]);
    l.push([n.x+offset, n.y-offset]);
    l.push([n.x+offset, n.y+offset]);
  }

  // create convex hulls
  var hullset = [];
  for (i in hulls) {
    hullset.push({group: i, path: d3.geom.hull(hulls[i])});
  }

  return hullset;
}

function drawCluster(d) {
  return curve(d.path); // 0.8
}

// --------------------------------------------------------

var body = d3.select("body");

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

d3.json("miserables.json", function(json) {
  data = json;
  for (var i=0; i<data.links.length; ++i) {
    o = data.links[i];
    o.source = data.nodes[o.source];
    o.target = data.nodes[o.target];
  }

  hullg = vis.append("g");
  linkg = vis.append("g");
  nodeg = vis.append("g");

  init();

  vis.attr("opacity", 1e-6)
    .transition()
      .duration(1000)
      .attr("opacity", 1);
});

function init() {
  if (force) force.stop();

  net = network(data, net, getGroup, expand);

  force = d3.layout.force()
      .nodes(net.nodes)
      .links(net.links)
      .size([width, height])
      .linkDistance(function(l, i) {
      var n1 = l.source, n2 = l.target;
    // larger distance for bigger groups:
    // both between single nodes and _other_ groups (where size of own node group still counts),
    // and between two group nodes.
    //
    // reduce distance for groups with very few outer links,
    // again both in expanded and grouped form, i.e. between individual nodes of a group and
    // nodes of another group or other group node or between two group nodes.
    //
    // The latter was done to keep the single-link groups ('blue', rose, ...) close.
    return 30 +
      Math.min(20 * Math.min((n1.size || (n1.group != n2.group ? n1.group_data.size : 0)),
                             (n2.size || (n1.group != n2.group ? n2.group_data.size : 0))),
           -30 +
           30 * Math.min((n1.link_count || (n1.group != n2.group ? n1.group_data.link_count : 0)),
                         (n2.link_count || (n1.group != n2.group ? n2.group_data.link_count : 0))),
           100);
      //return 150;
    })
    .linkStrength(function(l, i) {
    return 1;
    })
    .gravity(0.05)   // gravity+charge tweaked to ensure good 'grouped' view (e.g. green group not smack between blue&orange, ...
    .charge(-600)    // ... charge is important to turn single-linked groups to the outside
    .friction(0.5)   // friction adjusted to get dampened display: less bouncy bouncy ball [Swedish Chef, anyone?]
      .start();

  hullg.selectAll("path.hull").remove();
  hull = hullg.selectAll("path.hull")
      .data(convexHulls(net.nodes, getGroup, off))
    .enter().append("path")
      .attr("class", "hull")
      .attr("d", drawCluster)
      .style("fill", function(d) { return fill(d.group); })
      .on("click", function(d) {
console.log("hull click", d, arguments, this, expand[d.group]);
      expand[d.group] = false; init();
    });

  link = linkg.selectAll("line.link").data(net.links, linkid);
  link.exit().remove();
  link.enter().append("line")
      .attr("class", "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; })
      .style("stroke-width", function(d) { return d.size || 1; });

  node = nodeg.selectAll("circle.node").data(net.nodes, nodeid);
  node.exit().remove();
  node.enter().append("circle")
      // if (d.size) -- d.size > 0 when d is a group node.
      .attr("class", function(d) { return "node" + (d.size?"":" leaf"); })
      .attr("r", function(d) { return d.size ? d.size + dr : dr+1; })
      .attr("cx", function(d) { return d.x; })
      .attr("cy", function(d) { return d.y; })
      .style("fill", function(d) { return fill(d.group); })
      .on("click", function(d) {
console.log("node click", d, arguments, this, expand[d.group]);
        expand[d.group] = !expand[d.group];
    init();
      });

  node.call(force.drag);

  force.on("tick", function() {
    if (!hull.empty()) {
      hull.data(convexHulls(net.nodes, getGroup, off))
          .attr("d", drawCluster);
    }

    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; });
  });
}

    </script>
  </body>
</html>

## miserables.json
{"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":"Thenardier","group":4},{"name":"Cosette","group":5},{"name":"Javert","group":4},{"name":"Fauchelevent","group":0},{"name":"Bamatabois","group":2},{"name":"Perpetue","group":3},{"name":"Simplice","group":2},{"name":"Scaufflaire","group":2},{"name":"Woman1","group":2},{"name":"Judge","group":2},{"name":"Champmathieu","group":2},{"name":"Brevet","group":2},{"name":"Chenildieu","group":2},{"name":"Cochepaille","group":2},{"name":"Pontmercy","group":4},{"name":"Boulatruelle","group":6},{"name":"Eponine","group":4},{"name":"Anzelma","group":4},{"name":"Woman2","group":5},{"name":"MotherInnocent","group":0},{"name":"Gribier","group":0},{"name":"Jondrette","group":7},{"name":"Mme.Burgon","group":7},{"name":"Gavroche","group":8},{"name":"Gillenormand","group":5},{"name":"Magnon","group":5},{"name":"Mlle.Gillenormand","group":5},{"name":"Mme.Pontmercy","group":5},{"name":"Mlle.Vaubois","group":5},{"name":"Lt.Gillenormand","group":5},{"name":"Marius","group":8},{"name":"BaronessT","group":5},{"name":"Mabeuf","group":8},{"name":"Enjolras","group":8},{"name":"Combeferre","group":8},{"name":"Prouvaire","group":8},{"name":"Feuilly","group":8},{"name":"Courfeyrac","group":8},{"name":"Bahorel","group":8},{"name":"Bossuet","group":8},{"name":"Joly","group":8},{"name":"Grantaire","group":8},{"name":"MotherPlutarch","group":9},{"name":"Gueulemer","group":4},{"name":"Babet","group":4},{"name":"Claquesous","group":4},{"name":"Montparnasse","group":4},{"name":"Toussaint","group":5},{"name":"Child1","group":10},{"name":"Child2","group":10},{"name":"Brujon","group":4},{"name":"Mme.Hucheloup","group":8}],"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},{"source":4,"target":0,"value":1},{"source":5,"target":0,"value":1},{"source":6,"target":0,"value":1},{"source":7,"target":0,"value":1},{"source":8,"target":0,"value":2},{"source":9,"target":0,"value":1},{"source":11,"target":10,"value":1},{"source":11,"target":3,"value":3},{"source":11,"target":2,"value":3},{"source":11,"target":0,"value":5},{"source":12,"target":11,"value":1},{"source":13,"target":11,"value":1},{"source":14,"target":11,"value":1},{"source":15,"target":11,"value":1},{"source":17,"target":16,"value":4},{"source":18,"target":16,"value":4},{"source":18,"target":17,"value":4},{"source":19,"target":16,"value":4},{"source":19,"target":17,"value":4},{"source":19,"target":18,"value":4},{"source":20,"target":16,"value":3},{"source":20,"target":17,"value":3},{"source":20,"target":18,"value":3},{"source":20,"target":19,"value":4},{"source":21,"target":16,"value":3},{"source":21,"target":17,"value":3},{"source":21,"target":18,"value":3},{"source":21,"target":19,"value":3},{"source":21,"target":20,"value":5},{"source":22,"target":16,"value":3},{"source":22,"target":17,"value":3},{"source":22,"target":18,"value":3},{"source":22,"target":19,"value":3},{"source":22,"target":20,"value":4},{"source":22,"target":21,"value":4},{"source":23,"target":16,"value":3},{"source":23,"target":17,"value":3},{"source":23,"target":18,"value":3},{"source":23,"target":19,"value":3},{"source":23,"target":20,"value":4},{"source":23,"target":21,"value":4},{"source":23,"target":22,"value":4},{"source":23,"target":12,"value":2},{"source":23,"target":11,"value":9},{"source":24,"target":23,"value":2},{"source":24,"target":11,"value":7},{"source":25,"target":24,"value":13},{"source":25,"target":23,"value":1},{"source":25,"target":11,"value":12},{"source":26,"target":24,"value":4},{"source":26,"target":11,"value":31},{"source":26,"target":16,"value":1},{"source":26,"target":25,"value":1},{"source":27,"target":11,"value":17},{"source":27,"target":23,"value":5},{"source":27,"target":25,"value":5},{"source":27,"target":24,"value":1},{"source":27,"target":26,"value":1},{"source":28,"target":11,"value":8},{"source":28,"target":27,"value":1},{"source":29,"target":23,"value":1},{"source":29,"target":27,"value":1},{"source":29,"target":11,"value":2},{"source":30,"target":23,"value":1},{"source":31,"target":30,"value":2},{"source":31,"target":11,"value":3},{"source":31,"target":23,"value":2},{"source":31,"target":27,"value":1},{"source":32,"target":11,"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	Code derived from the d3.js 'force' example:

	The miserables.json file contains the weighted network of coappearances of
	characters in Victor Hugo's novel /Les Miserables/. Nodes represent characters
	as indicated by the labels, and edges connect any pair of characters that
	appear in the same chapter of the book. The values on the edges are the number
	of such coappearances. The data on coappearances were taken from D. E. Knuth,
	"The Stanford GraphBase: A Platform for Combinatorial Computing",
	Addison-Wesley, Reading, MA (1993).

	The group labels were transcribed from "Finding and evaluating community
	structure in networks" by M. E. J. Newman and M. Girvan.
	<!DOCTYPE html>
	<html>
	<head>
	<title>Clustered Network</title>
	<script src="http://d3js.org/d3.v2.js"></script>

	<style type="text/css">
	svg {
	border: 1px solid #ccc;
	}
	body {
	font: 10px sans-serif;
	}
	circle.node {
	fill: lightsteelblue;
	stroke: #555;
	stroke-width: 3px;
	}
	circle.leaf {
	stroke: #fff;
	stroke-width: 1.5px;
	}
	path.hull {
	fill: lightsteelblue;
	fill-opacity: 0.3;
	}
	line.link {
	stroke: #333;
	stroke-opacity: 0.5;
	pointer-events: none;
	}
	</style>
	</head>
	<body>
	<script type="text/javascript">
	var width = 960, // svg width
	height = 600, // svg height
	dr = 4, // default point radius
	off = 15, // cluster hull offset
	expand = {}, // expanded clusters
	data, net, force, hullg, hull, linkg, link, nodeg, node;

	var curve = d3.svg.line()
	.interpolate("cardinal-closed")
	.tension(.85);

	var fill = d3.scale.category20();

	function noop() { return false; }

	function nodeid(n) {
	return n.size ? "_g_"+n.group : n.name;
	}

	function linkid(l) {
	var u = nodeid(l.source),
	v = nodeid(l.target);
	return u<v ? u+"\|"+v : v+"\|"+u;
	}

	function getGroup(n) { return n.group; }

	// constructs the network to visualize
	function network(data, prev, index, expand) {
	expand = expand \|\| {};
	var gm = {}, // group map
	nm = {}, // node map
	lm = {}, // link map
	gn = {}, // previous group nodes
	gc = {}, // previous group centroids
	nodes = [], // output nodes
	links = []; // output links

	// process previous nodes for reuse or centroid calculation
	if (prev) {
	prev.nodes.forEach(function(n) {
	var i = index(n), o;
	if (n.size > 0) {
	gn[i] = n;
	n.size = 0;
	} else {
	o = gc[i] \|\| (gc[i] = {x:0,y:0,count:0});
	o.x += n.x;
	o.y += n.y;
	o.count += 1;
	}
	});
	}

	// determine nodes
	for (var k=0; k<data.nodes.length; ++k) {
	var n = data.nodes[k],
	i = index(n),
	l = gm[i] \|\| (gm[i]=gn[i]) \|\| (gm[i]={group:i, size:0, nodes:[]});

	if (expand[i]) {
	// the node should be directly visible
	nm[n.name] = nodes.length;
	nodes.push(n);
	if (gn[i]) {
	// place new nodes at cluster location (plus jitter)
	n.x = gn[i].x + Math.random();
	n.y = gn[i].y + Math.random();
	}
	} else {
	// the node is part of a collapsed cluster
	if (l.size == 0) {
	// if new cluster, add to set and position at centroid of leaf nodes
	nm[i] = nodes.length;
	nodes.push(l);
	if (gc[i]) {
	l.x = gc[i].x / gc[i].count;
	l.y = gc[i].y / gc[i].count;
	}
	}
	l.nodes.push(n);
	}
	// always count group size as we also use it to tweak the force graph strengths/distances
	l.size += 1;
	n.group_data = l;
	}

	for (i in gm) { gm[i].link_count = 0; }

	// determine links
	for (k=0; k<data.links.length; ++k) {
	var e = data.links[k],
	u = index(e.source),
	v = index(e.target);
	if (u != v) {
	gm[u].link_count++;
	gm[v].link_count++;
	}
	u = expand[u] ? nm[e.source.name] : nm[u];
	v = expand[v] ? nm[e.target.name] : nm[v];
	var i = (u<v ? u+"\|"+v : v+"\|"+u),
	l = lm[i] \|\| (lm[i] = {source:u, target:v, size:0});
	l.size += 1;
	}
	for (i in lm) { links.push(lm[i]); }

	return {nodes: nodes, links: links};
	}

	function convexHulls(nodes, index, offset) {
	var hulls = {};

	// create point sets
	for (var k=0; k<nodes.length; ++k) {
	var n = nodes[k];
	if (n.size) continue;
	var i = index(n),
	l = hulls[i] \|\| (hulls[i] = []);
	l.push([n.x-offset, n.y-offset]);
	l.push([n.x-offset, n.y+offset]);
	l.push([n.x+offset, n.y-offset]);
	l.push([n.x+offset, n.y+offset]);
	}

	// create convex hulls
	var hullset = [];
	for (i in hulls) {
	hullset.push({group: i, path: d3.geom.hull(hulls[i])});
	}

	return hullset;
	}

	function drawCluster(d) {
	return curve(d.path); // 0.8
	}

	// --------------------------------------------------------

	var body = d3.select("body");

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

	d3.json("miserables.json", function(json) {
	data = json;
	for (var i=0; i<data.links.length; ++i) {
	o = data.links[i];
	o.source = data.nodes[o.source];
	o.target = data.nodes[o.target];
	}

	hullg = vis.append("g");
	linkg = vis.append("g");
	nodeg = vis.append("g");

	init();

	vis.attr("opacity", 1e-6)
	.transition()
	.duration(1000)
	.attr("opacity", 1);
	});

	function init() {
	if (force) force.stop();

	net = network(data, net, getGroup, expand);

	force = d3.layout.force()
	.nodes(net.nodes)
	.links(net.links)
	.size([width, height])
	.linkDistance(function(l, i) {
	var n1 = l.source, n2 = l.target;
	// larger distance for bigger groups:
	// both between single nodes and _other_ groups (where size of own node group still counts),
	// and between two group nodes.
	//
	// reduce distance for groups with very few outer links,
	// again both in expanded and grouped form, i.e. between individual nodes of a group and
	// nodes of another group or other group node or between two group nodes.
	//
	// The latter was done to keep the single-link groups ('blue', rose, ...) close.
	return 30 +
	Math.min(20 * Math.min((n1.size \|\| (n1.group != n2.group ? n1.group_data.size : 0)),
	(n2.size \|\| (n1.group != n2.group ? n2.group_data.size : 0))),
	-30 +
	30 * Math.min((n1.link_count \|\| (n1.group != n2.group ? n1.group_data.link_count : 0)),
	(n2.link_count \|\| (n1.group != n2.group ? n2.group_data.link_count : 0))),
	100);
	//return 150;
	})
	.linkStrength(function(l, i) {
	return 1;
	})
	.gravity(0.05) // gravity+charge tweaked to ensure good 'grouped' view (e.g. green group not smack between blue&orange, ...
	.charge(-600) // ... charge is important to turn single-linked groups to the outside
	.friction(0.5) // friction adjusted to get dampened display: less bouncy bouncy ball [Swedish Chef, anyone?]
	.start();

	hullg.selectAll("path.hull").remove();
	hull = hullg.selectAll("path.hull")
	.data(convexHulls(net.nodes, getGroup, off))
	.enter().append("path")
	.attr("class", "hull")
	.attr("d", drawCluster)
	.style("fill", function(d) { return fill(d.group); })
	.on("click", function(d) {
	console.log("hull click", d, arguments, this, expand[d.group]);
	expand[d.group] = false; init();
	});

	link = linkg.selectAll("line.link").data(net.links, linkid);
	link.exit().remove();
	link.enter().append("line")
	.attr("class", "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; })
	.style("stroke-width", function(d) { return d.size \|\| 1; });

	node = nodeg.selectAll("circle.node").data(net.nodes, nodeid);
	node.exit().remove();
	node.enter().append("circle")
	// if (d.size) -- d.size > 0 when d is a group node.
	.attr("class", function(d) { return "node" + (d.size?"":" leaf"); })
	.attr("r", function(d) { return d.size ? d.size + dr : dr+1; })
	.attr("cx", function(d) { return d.x; })
	.attr("cy", function(d) { return d.y; })
	.style("fill", function(d) { return fill(d.group); })
	.on("click", function(d) {
	console.log("node click", d, arguments, this, expand[d.group]);
	expand[d.group] = !expand[d.group];
	init();
	});

	node.call(force.drag);

	force.on("tick", function() {
	if (!hull.empty()) {
	hull.data(convexHulls(net.nodes, getGroup, off))
	.attr("d", drawCluster);
	}

	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; });
	});
	}

	</script>
	</body>
	</html>