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treemap.js
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treemap.js
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// Squarified Treemaps by Mark Bruls, Kees Huizing, and Jarke J. van Wijk
// Modified to support a target aspect ratio by Jeff Heer
d3.layout.treemap = function() {
var hierarchy = d3.layout.hierarchy(),
round = Math.round,
size = [1, 1], // width, height
sticky = false,
stickies,
ratio = 0.5 * (1 + Math.sqrt(5)); // golden ratio
// Recursively compute the node area based on value & scale.
function scale(node, k) {
var children = node.children,
value = node.value;
node.area = isNaN(value) || value < 0 ? 0 : value * k;
if (children) {
var i = -1,
n = children.length;
while (++i < n) scale(children[i], k);
}
}
// Recursively arranges the specified node's children into squarified rows.
function squarify(node) {
if (!node.children) return;
var rect = {x: node.x, y: node.y, dx: node.dx, dy: node.dy},
row = [],
children = node.children.slice(), // copy-on-write
child,
best = Infinity, // the best row score so far
score, // the current row score
u = Math.min(rect.dx, rect.dy), // initial orientation
n;
row.area = 0;
while ((n = children.length) > 0) {
row.push(child = children[n - 1]);
row.area += child.area;
if ((score = worst(row, u)) <= best) { // continue with this orientation
children.pop();
best = score;
} else { // abort, and try a different orientation
row.area -= row.pop().area;
position(row, u, rect, false);
u = Math.min(rect.dx, rect.dy);
row.length = row.area = 0;
best = Infinity;
}
}
if (row.length) {
position(row, u, rect, true);
row.length = row.area = 0;
}
node.children.forEach(squarify);
}
// Recursively resizes the specified node's children into existing rows.
// Preserves the existing layout!
function stickify(node) {
if (!node.children) return;
var rect = {x: node.x, y: node.y, dx: node.dx, dy: node.dy},
children = node.children.slice(), // copy-on-write
child,
row = [];
row.area = 0;
while (child = children.pop()) {
row.push(child);
row.area += child.area;
if (child.z != null) {
position(row, child.z ? rect.dx : rect.dy, rect, !children.length);
row.length = row.area = 0;
}
}
node.children.forEach(stickify);
}
// Computes the score for the specified row, as the worst aspect ratio.
function worst(row, u) {
var s = row.area,
r,
rmax = 0,
rmin = Infinity,
i = -1,
n = row.length;
while (++i < n) {
r = row[i].area;
if (r < rmin) rmin = r;
if (r > rmax) rmax = r;
}
s *= s;
u *= u;
return rmin || rmax
? Math.max((u * rmax * ratio) / s, s / (u * rmin * ratio))
: Infinity;
}
// Positions the specified row of nodes. Modifies `rect`.
function position(row, u, rect, flush) {
var i = -1,
n = row.length,
x = rect.x,
y = rect.y,
v = u ? round(row.area / u) : 0,
o;
if (u == rect.dx) { // horizontal subdivision
if (flush || v > rect.dy) v = rect.dy; // over+underflow
while (++i < n) {
o = row[i];
o.x = x;
o.y = y;
o.dy = v;
x += o.dx = round(o.area / v);
}
o.z = true;
o.dx += rect.x + rect.dx - x; // rounding error
rect.y += v;
rect.dy -= v;
} else { // vertical subdivision
if (flush || v > rect.dx) v = rect.dx; // over+underflow
while (++i < n) {
o = row[i];
o.x = x;
o.y = y;
o.dx = v;
y += o.dy = round(o.area / v);
}
o.z = false;
o.dy += rect.y + rect.dy - y; // rounding error
rect.x += v;
rect.dx -= v;
}
}
function treemap(d) {
var nodes = stickies || hierarchy(d),
root = nodes[0];
root.x = 0;
root.y = 0;
root.dx = size[0];
root.dy = size[1];
if (stickies) hierarchy.revalue(root);
scale(root, size[0] * size[1] / root.value);
(stickies ? stickify : squarify)(root);
if (sticky) stickies = nodes;
return nodes;
}
treemap.size = function(x) {
if (!arguments.length) return size;
size = x;
return treemap;
};
treemap.round = function(x) {
if (!arguments.length) return round != Number;
round = x ? Math.round : Number;
return treemap;
};
treemap.sticky = function(x) {
if (!arguments.length) return sticky;
sticky = x;
stickies = null;
return treemap;
};
treemap.ratio = function(x) {
if (!arguments.length) return ratio;
ratio = x;
return treemap;
};
return d3_layout_hierarchyRebind(treemap, hierarchy);
};