Dynamically Updating A D3 Treemap Datasource - d3.js

Question

I think I'm missing something very obvious here. Basically what I am trying to do is create a treemap that on button click will go to the server and retrieve the next level into the treemap...This is necessary because the treemap structure is too large and takes too long to calculate so jumping one level at a time is the only option we have.
[Note to IE users, in this example the treemap node names don't appear to be working. Try using Chrome]
http://plnkr.co/edit/simVGU
This code is taken almost exactly from
http://bost.ocks.org/mike/treemap/
I'm using vizData1.json for the "first" level and on mouse click I'm using vizData2.json as the "second" level. You can see that the two end up overlapping. I've tried to do svg.exit() as well as svg.clear() without any luck.
I should also note that I have already tried the sticky(false) suggestion from this post
Does the d3 treemap layout get cached when a root node is passed to it?
UPDATE:
To continue my hunt I have found an example that successfully adds new nodes to an existing treemap. However I am having trouble adapting this logic as the treemap I am attempting to fit this logic into has been heavily customized by Michael Bostock - #mbostock to allow for the nice breadcrumb trail bar at the top.
Code snippet that proves appending to existing treemap nodes is possible:
http://jsfiddle.net/WB5jh/3/
Also, Stackoverflow is forcing me to post code because I'm linking to plnkr so I have dumped my script.js here for those who would rather not interact with plunker
$(function() {
var margin = { top: 20, right: 0, bottom: 0, left: 0 },
width = 960,
height = 500,
formatNumber = d3.format(",d"),
transitioning;
var x = d3.scale.linear()
.domain([0, width])
.range([0, width]);
var y = d3.scale.linear()
.domain([0, height])
.range([0, height]);
var treemap = d3.layout.treemap()
.children(function (d, depth) { return depth ? null : d._children; })
.sort(function (a, b) { return a.value - b.value; })
.ratio(height / width * 0.5 * (1 + Math.sqrt(5)))
.round(false)
.sticky(false);
var svg = d3.select("#treemap")
.append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.bottom + margin.top)
.style("margin-left", -margin.left + "px")
.style("margin.right", -margin.right + "px")
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")")
.style("shape-rendering", "crispEdges");
var grandparent = svg.append("g")
.attr("class", "grandparent");
grandparent.append("rect")
.attr("y", -margin.top)
.attr("width", width)
.attr("height", margin.top);
grandparent.append("text")
.attr("x", 6)
.attr("y", 6 - margin.top)
.attr("dy", ".75em");
d3.json("vizData1.json", function (root) {
initialize(root);
accumulate(root);
layout(root);
display(root);
});
function initialize(root) {
root.x = root.y = 0;
root.dx = width;
root.dy = height;
root.depth = 0;
}
// Aggregate the values for internal nodes. This is normally done by the
// treemap layout, but not here because of our custom implementation.
// We also take a snapshot of the original children (_children) to avoid
// the children being overwritten when when layout is computed.
function accumulate(d) {
return (d._children = d.children)
? d.value = d.children.reduce(function (p, v) { return p + accumulate(v); }, 0)
: d.value;
}
// Compute the treemap layout recursively such that each group of siblings
// uses the same size (1×1) rather than the dimensions of the parent cell.
// This optimizes the layout for the current zoom state. Note that a wrapper
// object is created for the parent node for each group of siblings so that
// the parent’s dimensions are not discarded as we recurse. Since each group
// of sibling was laid out in 1×1, we must rescale to fit using absolute
// coordinates. This lets us use a viewport to zoom.
function layout(d) {
if (d._children) {
treemap.nodes({ _children: d._children });
d._children.forEach(function (c) {
c.x = d.x + c.x * d.dx;
c.y = d.y + c.y * d.dy;
c.dx *= d.dx;
c.dy *= d.dy;
c.parent = d;
layout(c);
});
}
}
function display(d) {
console.log(d);
grandparent
.datum(d.parent)
.on("click", transition)
.select("text")
.text(name(d));
var g1 = svg.insert("g", ".grandparent")
.datum(d)
.attr("class", "depth");
var g = g1.selectAll("g")
.data(d._children)
.enter().append("g");
g.filter(function (d) { return d._children; })
.classed("children", true)
.on("click", transition);
g.selectAll(".child")
.data(function (d) { return d._children || [d]; })
.enter().append("rect")
.attr("class", "child")
.call(rect);
g.append("rect")
.attr("class", "parent")
.call(rect)
.append("title")
.text(function (d) { return formatNumber(d.value); });
g.append("foreignObject")
.call(rect)
.attr("class", "foreignobj")
.append("xhtml:div")
.attr("dy", ".75em")
.html(function (d) { return d.name; })
.attr("class", "textdiv");
function transition(d) {
if (transitioning || !d) return;
transitioning = true;
d3.json("vizData2.json", function (root) {
initialize(root);
accumulate(root);
layout(root);
display(root);
});
var g2 = display(d),
t1 = g1.transition().duration(750),
t2 = g2.transition().duration(750);
// Update the domain only after entering new elements.
x.domain([d.x, d.x + d.dx]);
y.domain([d.y, d.y + d.dy]);
// Enable anti-aliasing during the transition.
svg.style("shape-rendering", null);
// Draw child nodes on top of parent nodes.
svg.selectAll(".depth").sort(function (a, b) { return a.depth - b.depth; });
// Fade-in entering text.
g2.selectAll("text").style("fill-opacity", 0);
g2.selectAll("foreignObject div").style("display", "none"); /*added*/
// Transition to the new view.
t1.selectAll("text").call(text).style("fill-opacity", 0);
t2.selectAll("text").call(text).style("fill-opacity", 1);
t1.selectAll("rect").call(rect);
t2.selectAll("rect").call(rect);
t1.selectAll(".textdiv").style("display", "none"); /* added */
t1.selectAll(".foreignobj").call(foreign);
t2.selectAll(".textdiv").style("display", "block"); /* added */
t2.selectAll(".foreignobj").call(foreign); /* added */
// Remove the old node when the transition is finished.
t1.remove().each("end", function () {
svg.style("shape-rendering", "crispEdges");
transitioning = false;
});
}
return g;
}
function text(text) {
text.attr("x", function (d) { return x(d.x) + 6; })
.attr("y", function (d) { return y(d.y) + 6; });
}
function rect(rect) {
rect.attr("x", function (d) { return x(d.x); })
.attr("y", function (d) { return y(d.y); })
.attr("width", function (d) { return x(d.x + d.dx) - x(d.x); })
.attr("height", function (d) { return y(d.y + d.dy) - y(d.y); });
}
function foreign(foreign) { /* added */
foreign.attr("x", function (d) { return x(d.x); })
.attr("y", function (d) { return y(d.y); })
.attr("width", function (d) { return x(d.x + d.dx) - x(d.x); })
.attr("height", function (d) { return y(d.y + d.dy) - y(d.y); });
}
function name(d) {
return d.parent
? name(d.parent) + "." + d.name
: d.name;
}
});