This diagram shows the cash flows from a bull call spread strategy on BRK/B
Sankey Diagram for BRK/B BCS Strategy
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<!DOCTYPE html> | |
<meta charset="utf-8"> | |
<title>BCS Strategy BRK/B</title> | |
<style> | |
.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; | |
} | |
.link:hover { | |
stroke-opacity: .5; | |
} | |
</style> | |
<body> | |
<p id="chart"> | |
<script src="https://d3js.org/d3.v3.min.js"></script> | |
<script src="sankey.js"></script> | |
<script> | |
var units = "Widgets"; | |
var margin = {top: 10, right: 10, bottom: 10, left: 10}, | |
width = 700 - margin.left - margin.right, | |
height = 300 - margin.top - margin.bottom; | |
var formatNumber = d3.format(",.0f"), // zero decimal places | |
format = function(d) { return formatNumber(d) + " " + units; }, | |
color = d3.scale.category20(); | |
// append the svg canvas to the page | |
var svg = d3.select("#chart").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(36) | |
.nodePadding(40) | |
.size([width, height]); | |
var path = sankey.link(); | |
// load the data (using the timelyportfolio csv method) | |
d3.csv("sankey.csv", function(error, data) { | |
//set up graph in same style as original example but empty | |
graph = {"nodes" : [], "links" : []}; | |
data.forEach(function (d) { | |
graph.nodes.push({ "name": d.source }); | |
graph.nodes.push({ "name": d.target }); | |
graph.links.push({ "source": d.source, | |
"target": d.target, | |
"value": +d.value }); | |
}); | |
// return only the distinct / unique nodes | |
graph.nodes = d3.keys(d3.nest() | |
.key(function (d) { return d.name; }) | |
.map(graph.nodes)); | |
// loop through each link replacing the text with its index from node | |
graph.links.forEach(function (d, i) { | |
graph.links[i].source = graph.nodes.indexOf(graph.links[i].source); | |
graph.links[i].target = graph.nodes.indexOf(graph.links[i].target); | |
}); | |
//now loop through each nodes to make nodes an array of objects | |
// rather than an array of strings | |
graph.nodes.forEach(function (d, i) { | |
graph.nodes[i] = { "name": d }; | |
}); | |
sankey | |
.nodes(graph.nodes) | |
.links(graph.links) | |
.layout(32); | |
// add in the links | |
var link = svg.append("g").selectAll(".link") | |
.data(graph.links) | |
.enter().append("path") | |
.attr("class", "link") | |
.attr("d", path) | |
.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(graph.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)); | |
// add the rectangles for the nodes | |
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); }); | |
// 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); | |
} | |
}); | |
</script> | |
</body> | |
</html> |
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source | target | value | |
---|---|---|---|
Cash Invested | BCS 2016 110/120 | 5600 | |
BCS 2016 110/120 | Cash Out | 3658 | |
BCS 2016 110/120 | BCS 2017 145/155 | 5305 | |
BCS 2017 145/155 | Cash Out | 10000 | |
BCS 2016 110/120 | Interest | 1 | |
Interest | Cash Out | 585 |
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d3.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) { | |
nextNodes.push(link.target); | |
}); | |
}); | |
remainingNodes = nextNodes; | |
++x; | |
} | |
// | |
moveSinksRight(x); | |
scaleNodeBreadths((width - 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; | |
}; |
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