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Sankey with circular references
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript" src="http://d3js.org/d3.v2.js"></script>
<script type="text/javascript" src="sankey.js"></script>
<title>Sankey Diagram</title>
<style>
#chart {
height: 800px;
}
.node rect {
cursor: move;
fill-opacity: .9;
shape-rendering: crispEdges;
}
.node text {
pointer-events: none;
text-shadow: 0 1px 0 #fff;
}
.link {
fill: none;
stroke: #000;
stroke-opacity: .2;
}
.cycleLink {
fill: #600;
opacity: .2;
stroke: none;
stroke-linejoin: "round";
}
.cycleLink:hover {
opacity: .5;
}
.link:hover {
stroke-opacity: .5;
}
</style>
</head>
<body>
<h2>Random Chart</h2>
<p>The chart below is made from randomly generated data.
If it looks strange, try refreshing a few times.
</p>
<p>
The hope is to generate cycles in the data.
The cycles are styled as red to call them out for this example.
This rendering contains what I arrived at as the most reasonable
representation of cycles, featuring a smaller 'lane' at the top
of the chart where cycles travel.
</p>
<p id="chart"></p>
<script>
var margin = {top: 1, right: 1, bottom: 6, left: 1},
width = 960 - margin.left - margin.right,
height = 500 - margin.top - margin.bottom;
var formatNumber = d3.format(",.0f"),
format = function(d) { return formatNumber(d) + " tuples"; },
color = d3.scale.category20();
var sankey = d3.sankey()
.nodeWidth(15)
.nodePadding(10)
.size([width, height]);
var svg = d3.select("#chart").append("svg")
.attr( "preserveAspectRatio", "xMinYMid meet" )
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom);
var rootGraphic = svg
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
var path = sankey.link();
function createChart( energy ) {
sankey
.nodes(energy.nodes)
.links(energy.links)
.layout(32);
var allgraphics = svg.append("g").attr("id", "node-and-link-container" );
var link = allgraphics.append("g").attr("id", "link-container")
.selectAll(".link")
.data(energy.links)
.enter().append("path")
.attr("class", function(d) { return (d.causesCycle ? "cycleLink" : "link") })
.attr("d", path)
.sort(function(a, b) { return b.dy - a.dy; })
;
link.filter( function(d) { return !d.causesCycle} )
.style("stroke-width", function(d) { return Math.max(1, d.dy); })
link.append("title")
.text(function(d) { return d.source.name + " -> " + d.target.name + "\n" + format(d.value); });
var node = allgraphics.append("g").attr("id", "node-container")
.selectAll(".node")
.data(energy.nodes)
.enter().append("g")
.attr("class", "node")
.attr("transform", function(d) { return "translate(" + d.x + "," + d.y + ")"; })
.call(d3.behavior.drag()
.origin(function(d) { return d; })
.on("dragstart", function() { this.parentNode.appendChild(this); })
.on("drag", dragmove));
node.append("rect")
.attr("height", function(d) { return d.dy; })
.attr("width", sankey.nodeWidth())
.style("fill", function(d) { return d.color = color(d.name.replace(/ .*/, "")); })
.style("stroke", function(d) { return d3.rgb(d.color).darker(2); })
.append("title")
.text(function(d) { return d.name + "\n" + format(d.value); });
node.append("text")
.attr("x", -6)
.attr("y", function(d) { return d.dy / 2; })
.attr("dy", ".35em")
.attr("text-anchor", "end")
.attr("transform", null)
.text(function(d) { return d.name; })
.filter(function(d) { return d.x < width / 2; })
.attr("x", 6 + sankey.nodeWidth())
.attr("text-anchor", "start");
function dragmove(d) {
d3.select(this).attr("transform", "translate(" + d.x + "," + (d.y = Math.max(0, Math.min(height - d.dy, d3.event.y))) + ")");
sankey.relayout();
link.attr("d", path);
}
// I need to learn javascript
var numCycles = 0;
for( var i = 0; i< sankey.links().length; i++ ) {
if( sankey.links()[i].causesCycle ) {
numCycles++;
}
}
var cycleTopMarginSize = (sankey.cycleLaneDistFromFwdPaths() -
( (sankey.cycleLaneNarrowWidth() + sankey.cycleSmallWidthBuffer() ) * numCycles ) )
var horizontalMarginSize = ( sankey.cycleDistFromNode() + sankey.cycleControlPointDist() );
svg = d3.select("#chart").select("svg")
.attr( "viewBox",
"" + (0 - horizontalMarginSize ) + " " // left
+ cycleTopMarginSize + " " // top
+ (960 + horizontalMarginSize * 2 ) + " " // width
+ (500 + (-1 * cycleTopMarginSize)) + " " ); // height
};
function generateRandomData() {
var dataObject = new Object();
var mostNodes = 20;
var mostLinks = 40;
var numNodes = Math.floor((Math.random()*mostNodes)+1);
var numLinks = Math.floor((Math.random()*mostLinks)+1);
// Generate nodes
dataObject.nodes = new Array();
for( var n = 0; n < numNodes; n++ ) {
var node = new Object();
node.name = "Node-" + n;
dataObject.nodes[n] = node;
}
// Generate links
dataObject.links = new Array();
for( var i = 0; i < numLinks; i++ ) {
var link = new Object();
link.target = link.source = Math.floor((Math.random()*numNodes));
while( link.source === link.target ) { link.target = Math.floor((Math.random()*numNodes)); }
link.value = Math.floor((Math.random() * 100) + 1);
dataObject.links[i] = link;
}
return dataObject;
}
var energyData = generateRandomData();
createChart( energyData );
</script>
</body>
</html>
d3.sankey = function() {
var sankey = {},
nodeWidth = 24,
nodePadding = 8,
size = [1, 1],
nodes = [],
links = [],
// cycle features
cycleLaneNarrowWidth = 4,
cycleLaneDistFromFwdPaths = -10, // the distance above the paths to start showing 'cycle lanes'
cycleDistFromNode = 30, // linear path distance before arcing from node
cycleControlPointDist = 30, // controls the significance of the cycle's arc
cycleSmallWidthBuffer = 2 // distance between 'cycle lanes'
;
sankey.nodeWidth = function(_) {
if (!arguments.length) return nodeWidth;
nodeWidth = +_;
return sankey;
};
sankey.nodePadding = function(_) {
if (!arguments.length) return nodePadding;
nodePadding = +_;
return sankey;
};
// cycle related attributes
sankey.cycleLaneNarrowWidth = function(_) {
if (!arguments.length) return cycleLaneNarrowWidth;
cycleLaneNarrowWidth = +_;
return sankey;
}
sankey.cycleSmallWidthBuffer = function(_) {
if (!arguments.length) return cycleSmallWidthBuffer;
cycleSmallWidthBuffer = +_;
return sankey;
}
sankey.cycleLaneDistFromFwdPaths = function(_) {
if (!arguments.length) return cycleLaneDistFromFwdPaths;
cycleLaneDistFromFwdPaths = +_;
return sankey;
}
sankey.cycleDistFromNode = function(_) {
if (!arguments.length) return cycleDistFromNode;
cycleDistFromNode = +_;
return sankey;
}
sankey.cycleControlPointDist = function(_) {
if (!arguments.length) return cycleControlPointDist;
cycleControlPointDist = +_;
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.layout = function(iterations) {
computeNodeLinks();
computeNodeValues();
markCycles();
computeNodeBreadths();
computeNodeDepths(iterations);
computeLinkDepths();
return sankey;
};
sankey.relayout = function() {
computeLinkDepths();
return sankey;
};
sankey.link = function() {
var curvature = .5;
function link(d) {
if( d.causesCycle ) {
// cycle node; reaches backward
/*
The path will look like this, where
s=source, t=target, ?q=quadratic focus point
(wq)-> /-----n-----\
|w |
| e
\-t |
s--/ <-(eq)
*/
// Enclosed shape using curves n' stuff
var smallWidth = cycleLaneNarrowWidth,
s_x = d.source.x + d.source.dx,
s_y = d.source.y + d.sy + d.dy,
t_x = d.target.x,
t_y = d.target.y,
se_x = s_x + cycleDistFromNode,
se_y = s_y,
ne_x = se_x,
ne_y = cycleLaneDistFromFwdPaths - (d.cycleIndex * (smallWidth + cycleSmallWidthBuffer) ), // above regular paths, in it's own 'cycle lane', with a buffer around it
nw_x = t_x - cycleDistFromNode,
nw_y = ne_y,
sw_x = nw_x,
sw_y = t_y + d.ty + d.dy;
// start the path on the outer path boundary
return "M" + s_x + "," + s_y
+ "L" + se_x + "," + se_y
+ "C" + (se_x + cycleControlPointDist) + "," + se_y + " " + (ne_x + cycleControlPointDist) + "," + ne_y + " " + ne_x + "," + ne_y
+ "H" + nw_x
+ "C" + (nw_x - cycleControlPointDist) + "," + nw_y + " " + (sw_x - cycleControlPointDist) + "," + sw_y + " " + sw_x + "," + sw_y
+ "H" + t_x
//moving to inner path boundary
+ "V" + ( t_y + d.ty )
+ "H" + sw_x
+ "C" + (sw_x - (cycleControlPointDist/2) + smallWidth) + "," + t_y + " " +
(nw_x - (cycleControlPointDist/2) + smallWidth) + "," + (nw_y + smallWidth) + " " +
nw_x + "," + (nw_y + smallWidth)
+ "H" + (ne_x - smallWidth)
+ "C" + (ne_x + (cycleControlPointDist/2) - smallWidth) + "," + (ne_y + smallWidth) + " " +
(se_x + (cycleControlPointDist/2) - smallWidth) + "," + (se_y - d.dy) + " " +
se_x + "," + (se_y - d.dy)
+ "L" + s_x + "," + (s_y - d.dy);
} else {
// regular forward node
var x0 = d.source.x + d.source.dx,
x1 = d.target.x,
xi = d3.interpolateNumber(x0, x1),
x2 = xi(curvature),
x3 = xi(1 - curvature),
y0 = d.source.y + d.sy + d.dy / 2,
y1 = d.target.y + d.ty + d.dy / 2;
return "M" + x0 + "," + y0
+ "C" + x2 + "," + y0
+ " " + x3 + "," + y1
+ " " + x1 + "," + y1;
}
}
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) {
node.sourceLinks = [];
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;
while (remainingNodes.length) {
nextNodes = [];
remainingNodes.forEach(function(node) {
node.x = x;
node.dx = nodeWidth;
node.sourceLinks.forEach(function(link) {
if( !link.causesCycle ) {
nextNodes.push(link.target);
}
});
});
remainingNodes = nextNodes;
++x;
}
moveSinksRight(x);
scaleNodeBreadths((size[0] - nodeWidth) / (x - 1));
}
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;
});
}
function computeNodeDepths(iterations) {
var nodesByBreadth = d3.nest()
.key(function(d) { return d.x; })
.sortKeys(d3.ascending)
.entries(nodes)
.map(function(d) { return d.values; });
initializeNodeDepth();
resolveCollisions();
for (var alpha = 1; iterations > 0; --iterations) {
relaxRightToLeft(alpha *= .99);
resolveCollisions();
relaxLeftToRight(alpha);
resolveCollisions();
}
function initializeNodeDepth() {
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) {
var y = d3.sum(node.targetLinks, weightedSource) / d3.sum(node.targetLinks, value);
node.y += (y - center(node)) * alpha;
}
});
});
function weightedSource(link) {
return center(link.source) * link.value;
}
}
function relaxRightToLeft(alpha) {
nodesByBreadth.slice().reverse().forEach(function(nodes) {
nodes.forEach(function(node) {
if (node.sourceLinks.length) {
var y = d3.sum(node.sourceLinks, weightedTarget) / d3.sum(node.sourceLinks, value);
node.y += (y - center(node)) * alpha;
}
});
});
function weightedTarget(link) {
return center(link.target) * 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;
}
}
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;
}
}
function center(node) {
return node.y + node.dy / 2;
}
function value(link) {
return link.value;
}
/* Cycle Related computations */
function markCycles() {
// ideally, find the 'feedback arc set' and remove them.
// This way is expensive, but should be fine for small numbers of links
var cycleMakers = [];
var addedLinks = new Array();
links.forEach(function(link) {
if( createsCycle( link.source, link.target, addedLinks ) ) {
link.causesCycle=true;
link.cycleIndex = cycleMakers.length;
cycleMakers.push( link );
} else {
addedLinks.push(link);
}
});
};
function createsCycle( originalSource, nodeToCheck, graph ) {
if( graph.length == 0 ) {
return false;
}
var nextLinks = findLinksOutward( nodeToCheck, graph );
// leaf node check
if( nextLinks.length == 0 ) {
return false;
}
// cycle check
for( var i = 0; i < nextLinks.length; i++ ) {
var nextLink = nextLinks[i];
if( nextLink.target === originalSource ) {
return true;
}
// Recurse
if( createsCycle( originalSource, nextLink.target, graph ) ) {
return true;
}
}
// Exhausted all links
return false;
};
/* Given a node, find all links for which this is a source
in the current 'known' graph */
function findLinksOutward( node, graph ) {
var children = [];
for( var i = 0; i < graph.length; i++ ) {
if( node == graph[i].source ) {
children.push( graph[i] );
}
}
return children;
}
return sankey;
};
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