ZJONSSON/force_labels.js

## force_labels.js
(function() {
  d3.force_labels = function force_labels() {
    var labels = d3.layout.force();

    // Update the position of the anchor based on the center of bounding box
    function updateAnchor() {
      if (!labels.selection) return;
      labels.selection.each(function(d) {
        var bbox = this.getBBox(),
            x = bbox.x + bbox.width / 2,
            y = bbox.y + bbox.height / 2;

        d.anchorPos.x = x;
        d.anchorPos.y = y;

        // If a label position does not exist, set it to be the anchor position
        if (d.labelPos.x == null) {
          d.labelPos.x = x;
          d.labelPos.y = y;
        }
      });
    }

    //The anchor position should be updated on each tick
    labels.on("tick.labels", updateAnchor);

    // This updates all nodes/links - retaining any previous labelPos on updated nodes
    labels.update = function(selection) {
      labels.selection = selection;
      var nodes = [], links = [];
      selection[0].forEach(function(d) {
        if(d && d.__data__) {
          var data = d.__data__;

          if (!d.labelPos) d.labelPos = {fixed: false};
          if (!d.anchorPos) d.anchorPos = {fixed: true};

          // Place position objects in __data__ to make them available through
          // d.labelPos/d.anchorPos for different elements
          data.labelPos = d.labelPos;
          data.anchorPos = d.anchorPos;

          links.push({target: d.anchorPos, source: d.labelPos});
          nodes.push(d.anchorPos);
          nodes.push(d.labelPos);
        }
      });
      labels
          .stop()
          .nodes(nodes)
          .links(links);
      updateAnchor();
      labels.start();
    };
    return labels;
  };
})();

## index.html
<!DOCTYPE html>
<html>
<head>
    <script src="http://d3js.org/d3.v2.js"></script>
    <script type="text/javascript" src="force_labels.js"></script>
    <style>
    .anchor { fill:blue}
    .labelbox { fill:black;opacity:0.8}
    .labeltext { fill:white;font-weight:bold;text-anchor:middle;font-size:16;font-family:  serif}
    .link { stroke:gray;stroke-width:0.35}
    </style>
</head>

<body>
    <div style="width:150px;float:left">
        <span id="corr-label">Correlation: </span><br>
        <input type="range" min="-1.0" max="1.0" value="0.0" id="corr" step="0.01"/>
    </div>
    <div style="width:150px;float:left">
        <span id="charge-label">Label charge: </span><br>
        <input type="range" min="0" max="100" value="60.0" id="charge" step="1"/>
    </div>
    <button type="button" id="addone">Add one measurement</button>
    <button type="button" id="randomize20">Replace with 20</button>
    <button type="button" id="randomize50">Replace with 50</button>
    <button type="button" id="randomize100">Replace with 100</button>

<script type="text/javascript">
var w=960,h=500,
    x_mean = w/2,
    x_std = w/10,
    y_mean = h/2,
    y_std = h/10,
    labelBox,link,
    data=[];


var svg=d3.select("body")
    .append("svg:svg")
    .attr("height",h)
    .attr("width",w)

function refresh() {
    // plot the data as usual
    anchors = svg.selectAll(".anchor").data(data,function(d,i) { return i})
    anchors.exit().attr("class","exit").transition().duration(1000).style("opacity",0).remove()
    anchors.enter().append("circle").attr("class","anchor").attr("r",4).attr("cx",function(d) { return d.x}).attr("cy",function(d) { return h-d.y})
    anchors.transition()
        .delay(function(d,i) { return i*10})
        .duration(1500)
        .attr("cx",function(d) { return d.x})
        .attr("cy",function(d) { return h-d.y})


    // Now for the labels
    anchors.call(labelForce.update)  //  This is the only function call needed, the rest is just drawing the labels

    labels = svg.selectAll(".labels").data(data,function(d,i) { return i})
    labels.exit().attr("class","exit").transition().delay(0).duration(500).style("opacity",0).remove()

    // Draw the labelbox, caption and the link
        newLabels = labels.enter().append("g").attr("class","labels")

        newLabelBox = newLabels.append("g").attr("class","labelbox")
                newLabelBox.append("circle").attr("r",11)
                newLabelBox.append("text").attr("class","labeltext").attr("y",6)
        newLabels.append("line").attr("class","link")

        labelBox = svg.selectAll(".labels").selectAll(".labelbox")
        links = svg.selectAll(".link")
        labelBox.selectAll("text").text(function(d) { return d.num})

}

function redrawLabels() {
    labelBox
        .attr("transform",function(d) { return "translate("+d.labelPos.x+" "+d.labelPos.y+")"})

    links
        .attr("x1",function(d) { return d.anchorPos.x})
        .attr("y1",function(d) { return d.anchorPos.y})
        .attr("x2",function(d) { return d.labelPos.x})
        .attr("y2",function(d) { return d.labelPos.y})
}


// Initialize the label-forces
labelForce = d3.force_labels()
    .linkDistance(0.0)
    .gravity(0)
    .nodes([]).links([])
    .charge(-60)
    .on("tick",redrawLabels)


// and now for the data functionality
function randomize(count) {
    z1=d3.random.normal()
    z2=d3.random.normal()
    data=data.concat(d3.range(count || 100).map(function(d,i) { return {z1:z1(),z2:z2(),num:data.length+i}}))
    correlate()
}

function correlate() {
    var corr = d3.select("#corr").property("value")
    d3.select("#corr-label").text("Correlation: "+d3.format("%")(corr))

    data.forEach(function(d) { d.x = x_mean+(d.z1*x_std),
                                d.y = y_mean+y_std*(corr*d.z1+d.z2*Math.sqrt(1-Math.pow(corr,2)))})
    refresh()
}

// and finally hook up the controls

d3.select("#randomize20").on("click",function() { data=[];randomize(20)})
d3.select("#randomize50").on("click",function() { data=[];randomize(50)})
d3.select("#randomize100").on("click",function() { data=[];randomize(100)})
d3.select("#addone").on("click",function() { randomize(1)})
d3.select("#corr")
    .on("change",function() { d3.select("#corr-label").text("Correlation: "+d3.format("%")(this.value))})
    .on("mouseup",correlate)
d3.select("#charge")
    .on("change",function() {
        d3.select("#charge-label").text("Label charge: "+d3.format("f")(this.value))
        labelForce.charge(-this.value).start()
    })

randomize()
</script>
</body>
</html>

## thumbnail.png

      
          Raw
        
        
              thumbnail.png
	(function() {
	d3.force_labels = function force_labels() {
	var labels = d3.layout.force();

	// Update the position of the anchor based on the center of bounding box
	function updateAnchor() {
	if (!labels.selection) return;
	labels.selection.each(function(d) {
	var bbox = this.getBBox(),
	x = bbox.x + bbox.width / 2,
	y = bbox.y + bbox.height / 2;

	d.anchorPos.x = x;
	d.anchorPos.y = y;

	// If a label position does not exist, set it to be the anchor position
	if (d.labelPos.x == null) {
	d.labelPos.x = x;
	d.labelPos.y = y;
	}
	});
	}

	//The anchor position should be updated on each tick
	labels.on("tick.labels", updateAnchor);

	// This updates all nodes/links - retaining any previous labelPos on updated nodes
	labels.update = function(selection) {
	labels.selection = selection;
	var nodes = [], links = [];
	selection[0].forEach(function(d) {
	if(d && d.__data__) {
	var data = d.__data__;

	if (!d.labelPos) d.labelPos = {fixed: false};
	if (!d.anchorPos) d.anchorPos = {fixed: true};

	// Place position objects in __data__ to make them available through
	// d.labelPos/d.anchorPos for different elements
	data.labelPos = d.labelPos;
	data.anchorPos = d.anchorPos;

	links.push({target: d.anchorPos, source: d.labelPos});
	nodes.push(d.anchorPos);
	nodes.push(d.labelPos);
	}
	});
	labels
	.stop()
	.nodes(nodes)
	.links(links);
	updateAnchor();
	labels.start();
	};
	return labels;
	};
	})();
	<!DOCTYPE html>
	<html>
	<head>
	<script src="http://d3js.org/d3.v2.js"></script>
	<script type="text/javascript" src="force_labels.js"></script>
	<style>
	.anchor { fill:blue}
	.labelbox { fill:black;opacity:0.8}
	.labeltext { fill:white;font-weight:bold;text-anchor:middle;font-size:16;font-family: serif}
	.link { stroke:gray;stroke-width:0.35}
	</style>
	</head>

	<body>
	<div style="width:150px;float:left">
	<span id="corr-label">Correlation: </span><br>
	<input type="range" min="-1.0" max="1.0" value="0.0" id="corr" step="0.01"/>
	</div>
	<div style="width:150px;float:left">
	<span id="charge-label">Label charge: </span><br>
	<input type="range" min="0" max="100" value="60.0" id="charge" step="1"/>
	</div>
	<button type="button" id="addone">Add one measurement</button>
	<button type="button" id="randomize20">Replace with 20</button>
	<button type="button" id="randomize50">Replace with 50</button>
	<button type="button" id="randomize100">Replace with 100</button>

	<script type="text/javascript">
	var w=960,h=500,
	x_mean = w/2,
	x_std = w/10,
	y_mean = h/2,
	y_std = h/10,
	labelBox,link,
	data=[];


	var svg=d3.select("body")
	.append("svg:svg")
	.attr("height",h)
	.attr("width",w)

	function refresh() {
	// plot the data as usual
	anchors = svg.selectAll(".anchor").data(data,function(d,i) { return i})
	anchors.exit().attr("class","exit").transition().duration(1000).style("opacity",0).remove()
	anchors.enter().append("circle").attr("class","anchor").attr("r",4).attr("cx",function(d) { return d.x}).attr("cy",function(d) { return h-d.y})
	anchors.transition()
	.delay(function(d,i) { return i*10})
	.duration(1500)
	.attr("cx",function(d) { return d.x})
	.attr("cy",function(d) { return h-d.y})


	// Now for the labels
	anchors.call(labelForce.update) // This is the only function call needed, the rest is just drawing the labels

	labels = svg.selectAll(".labels").data(data,function(d,i) { return i})
	labels.exit().attr("class","exit").transition().delay(0).duration(500).style("opacity",0).remove()

	// Draw the labelbox, caption and the link
	newLabels = labels.enter().append("g").attr("class","labels")

	newLabelBox = newLabels.append("g").attr("class","labelbox")
	newLabelBox.append("circle").attr("r",11)
	newLabelBox.append("text").attr("class","labeltext").attr("y",6)
	newLabels.append("line").attr("class","link")

	labelBox = svg.selectAll(".labels").selectAll(".labelbox")
	links = svg.selectAll(".link")
	labelBox.selectAll("text").text(function(d) { return d.num})

	}

	function redrawLabels() {
	labelBox
	.attr("transform",function(d) { return "translate("+d.labelPos.x+" "+d.labelPos.y+")"})

	links
	.attr("x1",function(d) { return d.anchorPos.x})
	.attr("y1",function(d) { return d.anchorPos.y})
	.attr("x2",function(d) { return d.labelPos.x})
	.attr("y2",function(d) { return d.labelPos.y})
	}


	// Initialize the label-forces
	labelForce = d3.force_labels()
	.linkDistance(0.0)
	.gravity(0)
	.nodes([]).links([])
	.charge(-60)
	.on("tick",redrawLabels)



	// and now for the data functionality
	function randomize(count) {
	z1=d3.random.normal()
	z2=d3.random.normal()
	data=data.concat(d3.range(count \|\| 100).map(function(d,i) { return {z1:z1(),z2:z2(),num:data.length+i}}))
	correlate()
	}

	function correlate() {
	var corr = d3.select("#corr").property("value")
	d3.select("#corr-label").text("Correlation: "+d3.format("%")(corr))

	data.forEach(function(d) { d.x = x_mean+(d.z1*x_std),
	d.y = y_mean+y_std(corrd.z1+d.z2*Math.sqrt(1-Math.pow(corr,2)))})
	refresh()
	}

	// and finally hook up the controls

	d3.select("#randomize20").on("click",function() { data=[];randomize(20)})
	d3.select("#randomize50").on("click",function() { data=[];randomize(50)})
	d3.select("#randomize100").on("click",function() { data=[];randomize(100)})
	d3.select("#addone").on("click",function() { randomize(1)})
	d3.select("#corr")
	.on("change",function() { d3.select("#corr-label").text("Correlation: "+d3.format("%")(this.value))})
	.on("mouseup",correlate)
	d3.select("#charge")
	.on("change",function() {
	d3.select("#charge-label").text("Label charge: "+d3.format("f")(this.value))
	labelForce.charge(-this.value).start()
	})

	randomize()
	</script>
	</body>
	</html>