322 lines
9.3 KiB
JavaScript
Executable File
322 lines
9.3 KiB
JavaScript
Executable File
d3.sankey = function() {
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var sankey = {},
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nodeWidth = 24,
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nodePadding = 8, // was 8, needs to be much bigger. these numbers are actually overwritten in the html when we instantiate the viz!
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size = [1, 1],
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nodes = [],
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links = [];
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sankey.nodeWidth = function(_) {
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if (!arguments.length) return nodeWidth;
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nodeWidth = +_;
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return sankey;
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};
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sankey.nodePadding = function(_) {
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if (!arguments.length) return nodePadding;
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nodePadding = +_;
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return sankey;
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};
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sankey.nodes = function(_) {
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if (!arguments.length) return nodes;
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nodes = _;
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return sankey;
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};
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sankey.links = function(_) {
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if (!arguments.length) return links;
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links = _;
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return sankey;
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};
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sankey.size = function(_) {
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if (!arguments.length) return size;
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size = _;
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return sankey;
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};
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sankey.layout = function(iterations) {
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computeNodeLinks();
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computeNodeValues();
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// big changes here
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// change the order and depths (y pos) won't need iterations
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computeNodeDepths();
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computeNodeBreadths(iterations);
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computeLinkDepths();
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return sankey;
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};
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sankey.relayout = function() {
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computeLinkDepths();
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return sankey;
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};
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sankey.link = function() {
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var curvature = .5;
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// x0 = line start X
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// y0 = line start Y
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// x1 = line end X
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// y1 = line end Y
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// y2 = control point 1 (Y pos)
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// y3 = control point 2 (Y pos)
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function link(d) {
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// big changes here obviously, more comments to follow
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var x0 = d.source.x + d.sy + d.dy / 2,
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x1 = d.target.x + d.ty + d.dy / 2,
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y0 = d.source.y + nodeWidth,
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y1 = d.target.y,
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yi = d3.interpolateNumber(y0, y1),
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y2 = yi(curvature),
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y3 = yi(1 - curvature);
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// ToDo - nice to have - allow flow up or down! Plenty of use cases for starting at the bottom,
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// but main one is trickle down (economics, budgets etc), not up
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return "M" + x0 + "," + y0 // start (of SVG path)
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+ "C" + x0 + "," + y2 // CP1 (curve control point)
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+ " " + x1 + "," + y3 // CP2
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+ " " + x1 + "," + y1; // end
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}
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link.curvature = function(_) {
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if (!arguments.length) return curvature;
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curvature = +_;
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return link;
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};
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return link;
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};
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// Populate the sourceLinks and targetLinks for each node.
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// Also, if the source and target are not objects, assume they are indices.
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function computeNodeLinks() {
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nodes.forEach(function(node) {
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node.sourceLinks = [];
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node.targetLinks = [];
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});
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links.forEach(function(link) {
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var source = link.source,
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target = link.target;
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if (typeof source === "number") source = link.source = nodes[link.source];
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if (typeof target === "number") target = link.target = nodes[link.target];
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source.sourceLinks.push(link);
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target.targetLinks.push(link);
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});
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}
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// Compute the value (size) of each node by summing the associated links.
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function computeNodeValues() {
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nodes.forEach(function(node) {
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node.value = Math.max(
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d3.sum(node.sourceLinks, value),
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d3.sum(node.targetLinks, value)
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);
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});
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}
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// take a grouping of the nodes - the vertical columns
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// there shouldnt be 8 - there will be more, the total number of 1st level sources
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// then iterate over them and give them an incrementing x
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// because the data structure is ALL nodes, just flattened, don't just apply at the top level
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// then everything should have an X
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// THEN, for the Y
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// do the same thing, this time on the grouping of 8! i.e. 8 different Y values, not loads of different ones!
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function computeNodeBreadths(iterations) {
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var nodesByBreadth = d3.nest()
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.key(function(d) { return d.y; })
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.sortKeys(d3.ascending)
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.entries(nodes)
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.map(function(d) { return d.values; }); // values! we are using the values also as a way to seperate nodes (not just stroke width)?
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// this bit is actually the node sizes (widths)
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//var ky = (size[1] - (nodes.length - 1) * nodePadding) / d3.sum(nodes, value)
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// this should be only source nodes surely (level 1)
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var ky = (size[0] - (nodesByBreadth[0].length - 1) * nodePadding) / d3.sum(nodesByBreadth[0], value);
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// I'd like them to be much bigger, this calc doesn't seem to fill the space!?
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nodesByBreadth.forEach(function(nodes) {
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nodes.forEach(function(node, i) {
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node.x = i;
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node.dy = node.value * ky;
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});
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});
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links.forEach(function(link) {
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link.dy = link.value * ky;
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});
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resolveCollisions();
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for (var alpha = 1; iterations > 0; --iterations) {
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relaxLeftToRight(alpha);
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resolveCollisions();
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relaxRightToLeft(alpha *= .99);
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resolveCollisions();
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}
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// these relax methods should probably be operating on one level of the nodes, not all!?
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function relaxLeftToRight(alpha) {
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nodesByBreadth.forEach(function(nodes, breadth) {
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nodes.forEach(function(node) {
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if (node.targetLinks.length) {
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var y = d3.sum(node.targetLinks, weightedSource) / d3.sum(node.targetLinks, value);
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node.x += (y - center(node)) * alpha;
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}
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});
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});
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function weightedSource(link) {
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return center(link.source) * link.value;
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}
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}
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function relaxRightToLeft(alpha) {
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nodesByBreadth.slice().reverse().forEach(function(nodes) {
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nodes.forEach(function(node) {
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if (node.sourceLinks.length) {
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var y = d3.sum(node.sourceLinks, weightedTarget) / d3.sum(node.sourceLinks, value);
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node.x += (y - center(node)) * alpha;
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}
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});
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});
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function weightedTarget(link) {
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return center(link.target) * link.value;
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}
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}
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function resolveCollisions() {
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nodesByBreadth.forEach(function(nodes) {
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var node,
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dy,
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x0 = 0,
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n = nodes.length,
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i;
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// Push any overlapping nodes right.
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nodes.sort(ascendingDepth);
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for (i = 0; i < n; ++i) {
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node = nodes[i];
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dy = x0 - node.x;
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if (dy > 0) node.x += dy;
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x0 = node.x + node.dy + nodePadding;
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}
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// If the rightmost node goes outside the bounds, push it left.
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dy = x0 - nodePadding - size[0]; // was size[1]
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if (dy > 0) {
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x0 = node.x -= dy;
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// Push any overlapping nodes left.
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for (i = n - 2; i >= 0; --i) {
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node = nodes[i];
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dy = node.x + node.dy + nodePadding - x0; // was y0
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if (dy > 0) node.x -= dy;
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x0 = node.x;
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}
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}
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});
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}
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function ascendingDepth(a, b) {
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//return a.y - b.y; // flows go up
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return b.x - a.x; // flows go down
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//return a.x - b.x;
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}
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}
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// this moves all end points (sinks!) to the most extreme bottom
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function moveSinksDown(y) {
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nodes.forEach(function(node) {
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if (!node.sourceLinks.length) {
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node.y = y - 1;
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}
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});
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}
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// shift their locations out to occupy the screen
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function scaleNodeBreadths(kx) {
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nodes.forEach(function(node) {
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node.y *= kx;
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});
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}
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function computeNodeDepths() {
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var remainingNodes = nodes,
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nextNodes,
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y = 0;
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while (remainingNodes.length) {
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nextNodes = [];
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remainingNodes.forEach(function(node) {
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node.y = y;
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//node.dx = nodeWidth;
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node.sourceLinks.forEach(function(link) {
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if (nextNodes.indexOf(link.target) < 0) {
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nextNodes.push(link.target);
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}
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});
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});
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remainingNodes = nextNodes;
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++y;
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}
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// move end points to the very bottom
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moveSinksDown(y);
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scaleNodeBreadths((size[1] - nodeWidth) / (y - 1));
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}
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// .ty is the offset in terms of node position of the link (target)
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function computeLinkDepths() {
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nodes.forEach(function(node) {
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node.sourceLinks.sort(ascendingTargetDepth);
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node.targetLinks.sort(ascendingSourceDepth);
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});
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nodes.forEach(function(node) {
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var sy = 0, ty = 0;
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//ty = node.dy;
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node.sourceLinks.forEach(function(link) {
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link.sy = sy;
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sy += link.dy;
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});
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node.targetLinks.forEach(function(link) {
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// this is simply saying, for each target, keep adding the width of the link
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// so what if it was the other way round. start with full width then subtract?
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link.ty = ty;
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ty += link.dy;
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//ty -= link.dy;
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});
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});
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function ascendingSourceDepth(a, b) {
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//return a.source.y - b.source.y;
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return a.source.x - b.source.x;
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}
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function ascendingTargetDepth(a, b) {
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//return a.target.y - b.target.y;
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return a.target.x - b.target.x;
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}
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}
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function center(node) {
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return node.y + node.dy / 2;
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}
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function value(link) {
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return link.value;
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}
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return sankey;
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}; |