app/assets/javascripts/sankey.js
// Copyright (c) 2012-2015, Michael Bostock,
// Nathan Malkin, Kunal Bhalla, Claudiu Stefan Padurariu
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice, this
// list of conditions and the following disclaimer.
//
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// * The name Michael Bostock may not be used to endorse or promote products
// derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL MICHAEL BOSTOCK BE LIABLE FOR ANY DIRECT,
// INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
// EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// Adapted from https://github.com/kunalb/d3-plugins/blob/sankey/sankey/sankey.js
d3.sankey = function() {
var sankey = {},
nodeWidth = 24,
nodePadding = 8,
size = [1, 1],
nodes = [],
links = [],
components = [];
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();
computeNodeStructure();
computeNodeBreadths();
computeNodeDepths(iterations);
computeLinkDepths();
return sankey;
};
sankey.relayout = function() {
computeLinkDepths();
return sankey;
};
// A more involved path generator that requires 3 elements to render --
// It draws a starting element, intermediate and end element that are useful
// while drawing reverse links to get an appropriate fill.
//
// Each link is now an area and not a basic spline and no longer guarantees
// fixed width throughout.
//
// Sample usage:
//
// linkNodes = this._svg.append("g").selectAll(".link")
// .data(this.links)
// .enter().append("g")
// .attr("fill", "none")
// .attr("class", ".link")
// .sort(function(a, b) { return b.dy - a.dy; });
//
// linkNodePieces = [];
// for (var i = 0; i < 3; i++) {
// linkNodePieces[i] = linkNodes.append("path")
// .attr("class", ".linkPiece")
// .attr("d", path(i))
// .attr("fill", ...)
// }
sankey.reversibleLink = function() {
var curvature = .5;
// Used when source is behind target, the first and last paths are simple
// lines at the start and end node while the second path is the spline
function forwardLink(part, 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,
y1 = d.target.y + d.ty,
y2 = d.source.y + d.sy + d.dy,
y3 = d.target.y + d.ty + d.dy;
switch (part) {
case 0:
return "M" + x0 + "," + y0 + "L" + x0 + "," + (y0 + d.dy);
case 1:
return "M" + x0 + "," + y0
+ "C" + x2 + "," + y0 + " " + x3 + "," + y1 + " " + x1 + "," + y1
+ "L" + x1 + "," + y3
+ "C" + x3 + "," + y3 + " " + x2 + "," + y2 + " " + x0 + "," + y2
+ "Z";
case 2:
return "M" + x1 + "," + y1 + "L" + x1 + "," + (y1 + d.dy);
}
}
// Used for self loops and when the source is actually in front of the
// target; the first element is a turning path from the source to the
// destination, the second element connects the two twists and the last
// twists into the target element.
//
//
// /--Target
// \----------------------\
// Source--/
//
function backwardLink(part, d) {
var curveExtension = 30;
var curveDepth = 15;
function getDir(d) {
return d.source.y + d.sy > d.target.y + d.ty ? -1 : 1;
}
function p(x, y) {
return x + "," + y + " ";
}
var dt = getDir(d) * curveDepth,
x0 = d.source.x + d.source.dx,
y0 = d.source.y + d.sy,
x1 = d.target.x,
y1 = d.target.y + d.ty;
switch (part) {
case 0:
return "M" + p(x0, y0) +
"C" + p(x0, y0) +
p(x0 + curveExtension, y0) +
p(x0 + curveExtension, y0 + dt) +
"L" + p(x0 + curveExtension, y0 + dt + d.dy) +
"C" + p(x0 + curveExtension, y0 + d.dy) +
p(x0, y0 + d.dy) +
p(x0, y0 + d.dy) +
"Z";
case 1:
return "M" + p(x0 + curveExtension, y0 + dt) +
"C" + p(x0 + curveExtension, y0 + 3 * dt) +
p(x1 - curveExtension, y1 - 3 * dt) +
p(x1 - curveExtension, y1 - dt) +
"L" + p(x1 - curveExtension, y1 - dt + d.dy) +
"C" + p(x1 - curveExtension, y1 - 3 * dt + d.dy) +
p(x0 + curveExtension, y0 + 3 * dt + d.dy) +
p(x0 + curveExtension, y0 + dt + d.dy) +
"Z";
case 2:
return "M" + p(x1 - curveExtension, y1 - dt) +
"C" + p(x1 - curveExtension, y1) +
p(x1, y1) +
p(x1, y1) +
"L" + p(x1, y1 + d.dy) +
"C" + p(x1, y1 + d.dy) +
p(x1 - curveExtension, y1 + d.dy) +
p(x1 - curveExtension, y1 + d.dy - dt) +
"Z";
}
}
return function(part) {
return function(d) {
if (d.source.x < d.target.x) {
return forwardLink(part, d);
} else {
return backwardLink(part, d);
}
}
}
};
// The standard link path using a constant width spline that needs a
// single path element.
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) {
if (!(node.value)) //if not already given
node.value = Math.max(
d3.sum(node.sourceLinks, value),
d3.sum(node.targetLinks, value)
);
});
}
// Take the list of nodes and create a DAG of supervertices, each consisting
// of a strongly connected component of the graph
//
// Based off:
// http://en.wikipedia.org/wiki/Tarjan's_strongly_connected_components_algorithm
function computeNodeStructure() {
var nodeStack = [],
index = 0;
nodes.forEach(function(node) {
if (!node.index) {
connect(node);
}
});
function connect(node) {
node.index = index++;
node.lowIndex = node.index;
node.onStack = true;
nodeStack.push(node);
if (node.sourceLinks) {
node.sourceLinks.forEach(function(sourceLink){
var target = sourceLink.target;
if (!target.hasOwnProperty('index')) {
connect(target);
node.lowIndex = Math.min(node.lowIndex, target.lowIndex);
} else if (target.onStack) {
node.lowIndex = Math.min(node.lowIndex, target.index);
}
});
if (node.lowIndex === node.index) {
var component = [], currentNode;
do {
currentNode = nodeStack.pop()
currentNode.onStack = false;
component.push(currentNode);
} while (currentNode != node);
components.push({
root: node,
scc: component
});
}
}
}
components.forEach(function(component, i){
component.index = i;
component.scc.forEach(function(node) {
node.component = i;
});
});
}
// Assign the breadth (x-position) for each strongly connected component,
// followed by assigning breadth within the component.
function computeNodeBreadths() {
layerComponents();
components.forEach(function(component, i){
bfs(component.root, function(node){
var result = node.sourceLinks
.filter(function(sourceLink){
return sourceLink.target.component == i;
})
.map(function(sourceLink){
return sourceLink.target;
});
return result;
});
});
var max = 0;
var componentsByBreadth = d3.nest()
.key(function(d) { return d.x; })
// .sortKeys(d3.ascending)
.entries(components)
.map(function(d) { return d.values; });
var max = -1, nextMax = -1;
componentsByBreadth.forEach(function(c){
c.forEach(function(component){
component.x = max + 1;
component.scc.forEach(function(node){
if (node.layer)
node.x = node.layer;
else
node.x = component.x + node.x;
nextMax = Math.max(nextMax, node.x);
});
});
max = nextMax;
});
nodes
.filter(function(node) {
var outLinks = node.sourceLinks.filter(function(link){ return link.source.name != link.target.name; });
return (outLinks.length == 0);
})
.forEach(function(node) { node.x = max; })
scaleNodeBreadths((size[0] - nodeWidth) / Math.max(max, 1));
function flatten(a) {
return [].concat.apply([], a);
}
function layerComponents() {
var remainingComponents = components,
nextComponents,
visitedIndex,
x = 0;
while (remainingComponents.length) {
nextComponents = [];
visitedIndex = {};
remainingComponents.forEach(function(component) {
component.x = x;
component.scc.forEach(function(n) {
n.sourceLinks.forEach(function(l) {
if (!visitedIndex.hasOwnProperty(l.target.component) &&
l.target.component != component.index) {
nextComponents.push(components[l.target.component]);
visitedIndex[l.target.component] = true;
}
})
});
});
remainingComponents = nextComponents;
++x;
}
}
function bfs(node, extractTargets) {
var queue = [node], currentCount = 1, nextCount = 0;
var x = 0;
while(currentCount > 0) {
var currentNode = queue.shift();
currentCount--;
if (!currentNode.hasOwnProperty('x')) {
currentNode.x = x;
currentNode.dx = nodeWidth;
var targets = extractTargets(currentNode);
queue = queue.concat(targets);
nextCount += targets.length;
}
if (currentCount == 0) { // level change
x++;
currentCount = nextCount;
nextCount = 0;
}
}
}
}
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;
};