Create a Sankey diagram from a CSV file. I got most of this code from d3noob’s block, but I added the code to convert the CSV data into the format required by d3-sankey.
In this version, the links are colored as a linear gradient, transitioning from the color of the source to that of the target. In version 1, the links were not colored. In version 2, the links were colored according to this source.
My verdict: A single color is the easiest to read.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<style>
body {
margin: 0;
font-family: "Helvetica Neue", sans-serif;
}
.node rect {
cursor: move;
fill-opacity: .9;
shape-rendering: crispEdges;
}
.node text {
pointer-events: none;
text-shadow: 0px 0px 2px #fff;
font-size: .8em;
}
.link {
fill: none;
stroke: #000;
stroke-opacity: .5;
}
.link:hover {
stroke-opacity: 1;
}
</style>
</head>
<body>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script src="sankey.js"></script>
<script>
// set the dimensions and margins of the graph
var margin = {top: 10, right: 10, bottom: 10, left: 10},
width = window.innerWidth - margin.left - margin.right,
height = window.innerHeight - margin.top - margin.bottom;
// format variables
var formatNumber = d3.format(",.0f"), // zero decimal places
format = function(d) { return "$" + formatNumber(d); },
color = d3.scaleOrdinal(d3.schemeCategory20);
// append the svg object to the body of the page
var svg = d3.select("body").append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
// Set the sankey diagram properties
var sankey = d3.sankey()
.nodeWidth(10)
.nodePadding(10)
.size([width, height]);
var path = sankey.link();
// defs for the linear gradients
var defs = svg.append("defs");
// load the data
d3.queue()
.defer(d3.csv, "data.csv")
.await(ready);
function ready(error, csv){
// create an array to push all sources and targets, before making them unique
var arr = [];
csv.forEach(function(d){
arr.push(d.source);
arr.push(d.target);
});
// create nodes array
var nodes = arr.filter(onlyUnique).map(function(d,i){
return {
node: i,
name: d
}
});
// create links array
var links = csv.map(function(csv_row){
return {
source: getNode("source"),
target: getNode("target"),
value: +csv_row.value
}
function getNode(type){
return nodes.filter(function(node_object){ return node_object.name == csv_row[type]; })[0].node;
}
});
sankey
.nodes(nodes)
.links(links)
.layout(32);
// add in the links
var link = svg.append("g").selectAll(".link")
.data(links)
.enter().append("path")
.attr("class", "link")
.attr("d", path)
.style("stroke", function(d, i){
// create the gradient
var gradient_id = "gradient-" + i;
var gradient = defs.append("linearGradient")
.attr("id", gradient_id);
gradient.append("stop")
.attr("offset", "5%")
.attr("stop-color", color(d.source.name.replace(/ .*/, "")));
gradient.append("stop")
.attr("offset", "95%")
.attr("stop-color", color(d.target.name.replace(/ .*/, "")));
// TODO: Figure out what the hell is happening with bob and jimmy
return i == 0 ? color(d.source.name.replace(/ .*/, "")) : "url(#" + gradient_id + ")";
// return "url(#" + gradient_id + ")";
})
.style("stroke-width", function(d) { return Math.max(1, d.dy); })
.sort(function(a, b) { return b.dy - a.dy; });
// add the link titles
link.append("title")
.text(function(d) {
return d.source.name + " → " +
d.target.name + "\n" + format(d.value); });
// add in the nodes
var node = svg.append("g").selectAll(".node")
.data(nodes)
.enter().append("g")
.attr("class", "node")
.attr("transform", function(d) {
return "translate(" + d.x + "," + d.y + ")";
})
.call(d3.drag()
.subject(function(d) {
return d;
})
.on("start", function() {
this.parentNode.appendChild(this);
})
.on("drag", dragmove));
// add the rectangles for the nodes
node.append("rect")
.attr("height", function(d) { return d.dy < 0 ? .1 : 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);
});
// add in the title for the nodes
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");
// the function for moving the nodes
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);
}
}
// unique values of an array
function onlyUnique(value, index, self) {
return self.indexOf(value) === index;
}
</script>
</body>
</html>source,target,value
Bob,Jimmy,30000000
Joey,Bunk,632000000
Joey,Lester,100000000
Joey,Kima,541000000
Joey,Sidnor,7500000
Joey,Roland,15000000
Joey,Cedric,20000000
Steve,Kima,30000000
Steve,Cedric,10000000
Ross,Jay,15384115
Ross,Bunk,21000034
Ross,Lester,52563320
Ross,Kima,99039298
Ross,Phoebe,5910000
Ross,Sidnor,18872439
Ross,Chandler,6797000
Ross,Cedric,13105704
John,Bunk,1072500000
John,Lester,2500000
John,Kima,187500000
John,Phoebe,10000000
John,Monica,10000000
John,Chandler,10000000
John,Rachel,10000000
Tim,Bunk,20000000
Tim,Rachel,10000000d3.sankey = function() {
var sankey = {},
nodeWidth = 24,
nodePadding = 8,
size = [1, 1],
nodes = [],
links = [];
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.layout = function(iterations) {
computeNodeLinks();
computeNodeValues();
computeNodeBreadths();
computeNodeDepths(iterations);
computeLinkDepths();
return sankey;
};
sankey.relayout = function() {
computeLinkDepths();
return sankey;
};
sankey.link = function() {
var curvature = .5;
function link(d) {
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 (nextNodes.indexOf(link.target) < 0) {
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;
}
return sankey;
};