jeremykidwell.info/static/javascripts/sankey-1/sankey.js
Jeremy Kidwell 13e2fd6e74 first commit
2017-06-26 20:57:02 +01:00

397 lines
11 KiB
JavaScript
Executable file

d3.sankey = function() {
var sankey = {},
nodeWidth = 24,
nodePadding = 8,
size = [1, 1],
nodes = [],
links = [],
sinksRight = true;
sankey.nodeWidth = function(_) {
if (!arguments.length) return nodeWidth;
nodeWidth = +_;
return sankey;
};
sankey.nodePadding = function(_) {
if (!arguments.length) return nodePadding;
nodePadding = +_;
return sankey;
};
sankey.nodes = function(_) {
if (!arguments.length) return nodes;
nodes = _;
return sankey;
};
sankey.links = function(_) {
if (!arguments.length) return links;
links = _;
return sankey;
};
sankey.size = function(_) {
if (!arguments.length) return size;
size = _;
return sankey;
};
sankey.sinksRight = function (_) {
if (!arguments.length) return sinksRight;
sinksRight = _;
return sankey;
};
sankey.layout = function(iterations) {
computeNodeLinks();
computeNodeValues();
computeNodeBreadths();
computeNodeDepths(iterations);
return sankey;
};
sankey.relayout = function() {
computeLinkDepths();
return sankey;
};
// SVG path data generator, to be used as "d" attribute on "path" element selection.
sankey.link = function() {
var curvature = .5;
function link(d) {
var xs = d.source.x + d.source.dx,
xt = d.target.x,
xi = d3.interpolateNumber(xs, xt),
xsc = xi(curvature),
xtc = xi(1 - curvature),
ys = d.source.y + d.sy + d.dy / 2,
yt = d.target.y + d.ty + d.dy / 2;
if (!d.cycleBreaker) {
return "M" + xs + "," + ys
+ "C" + xsc + "," + ys
+ " " + xtc + "," + yt
+ " " + xt + "," + yt;
} else {
var xdelta = (1.5 * d.dy + 0.05 * Math.abs(xs - xt));
xsc = xs + xdelta;
xtc = xt - xdelta;
var xm = xi(0.5);
var ym = d3.interpolateNumber(ys, yt)(0.5);
var ydelta = (2 * d.dy + 0.1 * Math.abs(xs - xt) + 0.1 * Math.abs(ys - yt)) * (ym < (size[1] / 2) ? -1 : 1);
return "M" + xs + "," + ys
+ "C" + xsc + "," + ys
+ " " + xsc + "," + (ys + ydelta)
+ " " + xm + "," + (ym + ydelta)
+ "S" + xtc + "," + yt
+ " " + xt + "," + yt;
}
}
link.curvature = function(_) {
if (!arguments.length) return curvature;
curvature = +_;
return link;
};
return link;
};
// Populate the sourceLinks and targetLinks for each node.
// Also, if the source and target are not objects, assume they are indices.
function computeNodeLinks() {
nodes.forEach(function(node) {
// Links that have this node as source.
node.sourceLinks = [];
// Links that have this node as target.
node.targetLinks = [];
});
links.forEach(function(link) {
var source = link.source,
target = link.target;
if (typeof source === "number") source = link.source = nodes[link.source];
if (typeof target === "number") target = link.target = nodes[link.target];
source.sourceLinks.push(link);
target.targetLinks.push(link);
});
}
// Compute the value (size) of each node by summing the associated links.
function computeNodeValues() {
nodes.forEach(function(node) {
node.value = Math.max(
d3.sum(node.sourceLinks, value),
d3.sum(node.targetLinks, value)
);
});
}
// Iteratively assign the breadth (x-position) for each node.
// Nodes are assigned the maximum breadth of incoming neighbors plus one;
// nodes with no incoming links are assigned breadth zero, while
// nodes with no outgoing links are assigned the maximum breadth.
function computeNodeBreadths() {
var remainingNodes = nodes,
nextNodes,
x = 0;
// Work from left to right.
// Keep updating the breath (x-position) of nodes that are target of recently updated nodes.
while (remainingNodes.length && x < nodes.length) {
nextNodes = [];
remainingNodes.forEach(function(node) {
node.x = x;
node.dx = nodeWidth;
node.sourceLinks.forEach(function(link) {
if (nextNodes.indexOf(link.target) < 0 && !link.cycleBreaker) {
nextNodes.push(link.target);
}
});
});
if (nextNodes.length == remainingNodes.length) {
// There must be a cycle here. Let's search for a link that breaks it.
findAndMarkCycleBreaker(nextNodes);
// Start over.
// TODO: make this optional?
return computeNodeBreadths();
}
else {
remainingNodes = nextNodes;
++x;
}
}
// Optionally move pure sinks always to the right.
if (sinksRight) {
moveSinksRight(x);
}
scaleNodeBreadths((size[0] - nodeWidth) / (x - 1));
}
// Find a link that breaks a cycle in the graph (if any).
function findAndMarkCycleBreaker(nodes) {
// Go through all nodes from the given subset and traverse links searching for cycles.
var link;
for (var n=nodes.length - 1; n >= 0; n--) {
link = depthFirstCycleSearch(nodes[n], []);
if (link) {
return link;
}
}
// Depth-first search to find a link that is part of a cycle.
function depthFirstCycleSearch(cursorNode, path) {
var target, link;
for (var n = cursorNode.sourceLinks.length - 1; n >= 0; n--) {
link = cursorNode.sourceLinks[n];
if (link.cycleBreaker) {
// Skip already known cycle breakers.
continue;
}
// Check if target of link makes a cycle in current path.
target = link.target;
for (var l = 0; l < path.length; l++) {
if (path[l].source == target) {
// We found a cycle. Search for weakest link in cycle
var weakest = link;
for (; l < path.length; l++) {
if (path[l].value < weakest.value) {
weakest = path[l];
}
}
// Mark weakest link as (known) cycle breaker and abort search.
weakest.cycleBreaker = true;
return weakest;
}
}
// Recurse deeper.
path.push(link);
link = depthFirstCycleSearch(target, path);
path.pop();
// Stop further search if we found a cycle breaker.
if (link) {
return link;
}
}
}
}
function moveSourcesRight() {
nodes.forEach(function(node) {
if (!node.targetLinks.length) {
node.x = d3.min(node.sourceLinks, function(d) { return d.target.x; }) - 1;
}
});
}
function moveSinksRight(x) {
nodes.forEach(function(node) {
if (!node.sourceLinks.length) {
node.x = x - 1;
}
});
}
function scaleNodeBreadths(kx) {
nodes.forEach(function(node) {
node.x *= kx;
});
}
// Compute the depth (y-position) for each node.
function computeNodeDepths(iterations) {
// Group nodes by breath.
var nodesByBreadth = d3.nest()
.key(function(d) { return d.x; })
.sortKeys(d3.ascending)
.entries(nodes)
.map(function(d) { return d.values; });
//
initializeNodeDepth();
resolveCollisions();
computeLinkDepths();
for (var alpha = 1; iterations > 0; --iterations) {
relaxRightToLeft(alpha *= .99);
resolveCollisions();
computeLinkDepths();
relaxLeftToRight(alpha);
resolveCollisions();
computeLinkDepths();
}
function initializeNodeDepth() {
// Calculate vertical scaling factor.
var ky = d3.min(nodesByBreadth, function(nodes) {
return (size[1] - (nodes.length - 1) * nodePadding) / d3.sum(nodes, value);
});
nodesByBreadth.forEach(function(nodes) {
nodes.forEach(function(node, i) {
node.y = i;
node.dy = node.value * ky;
});
});
links.forEach(function(link) {
link.dy = link.value * ky;
});
}
function relaxLeftToRight(alpha) {
nodesByBreadth.forEach(function(nodes, breadth) {
nodes.forEach(function(node) {
if (node.targetLinks.length) {
// Value-weighted average of the y-position of source node centers linked to this node.
var y = d3.sum(node.targetLinks, weightedSource) / d3.sum(node.targetLinks, value);
node.y += (y - center(node)) * alpha;
}
});
});
function weightedSource(link) {
return (link.source.y + link.sy + link.dy / 2) * link.value;
}
}
function relaxRightToLeft(alpha) {
nodesByBreadth.slice().reverse().forEach(function(nodes) {
nodes.forEach(function(node) {
if (node.sourceLinks.length) {
// Value-weighted average of the y-positions of target nodes linked to this node.
var y = d3.sum(node.sourceLinks, weightedTarget) / d3.sum(node.sourceLinks, value);
node.y += (y - center(node)) * alpha;
}
});
});
function weightedTarget(link) {
return (link.target.y + link.ty + link.dy / 2) * link.value;
}
}
function resolveCollisions() {
nodesByBreadth.forEach(function(nodes) {
var node,
dy,
y0 = 0,
n = nodes.length,
i;
// Push any overlapping nodes down.
nodes.sort(ascendingDepth);
for (i = 0; i < n; ++i) {
node = nodes[i];
dy = y0 - node.y;
if (dy > 0) node.y += dy;
y0 = node.y + node.dy + nodePadding;
}
// If the bottommost node goes outside the bounds, push it back up.
dy = y0 - nodePadding - size[1];
if (dy > 0) {
y0 = node.y -= dy;
// Push any overlapping nodes back up.
for (i = n - 2; i >= 0; --i) {
node = nodes[i];
dy = node.y + node.dy + nodePadding - y0;
if (dy > 0) node.y -= dy;
y0 = node.y;
}
}
});
}
function ascendingDepth(a, b) {
return a.y - b.y;
}
}
// Compute y-offset of the source endpoint (sy) and target endpoints (ty) of links,
// relative to the source/target node's y-position.
function computeLinkDepths() {
nodes.forEach(function(node) {
node.sourceLinks.sort(ascendingTargetDepth);
node.targetLinks.sort(ascendingSourceDepth);
});
nodes.forEach(function(node) {
var sy = 0, ty = 0;
node.sourceLinks.forEach(function(link) {
link.sy = sy;
sy += link.dy;
});
node.targetLinks.forEach(function(link) {
link.ty = ty;
ty += link.dy;
});
});
function ascendingSourceDepth(a, b) {
return a.source.y - b.source.y;
}
function ascendingTargetDepth(a, b) {
return a.target.y - b.target.y;
}
}
// Y-position of the middle of a node.
function center(node) {
return node.y + node.dy / 2;
}
// Value property accessor.
function value(x) {
return x.value;
}
return sankey;
};