25:["$","title",null,{"children":"Sankey diagram | Ford Johnson | Observable"}] 49:Tbfe,chart = { // Specify the dimensions of the chart. const width = 928; const height = 600; const format = d3.format(",.0f"); // Create a SVG container. const svg = d3.create("svg") .attr("width", width) .attr("height", height) .attr("viewBox", [0, 0, width, height]) .attr("style", "max-width: 100%; height: auto; font: 10px sans-serif;"); // Constructs and configures a Sankey generator. const sankey = d3.sankey() .nodeId(d => d.name) .nodeAlign(d3[nodeAlign]) // d3.sankeyLeft, etc. .nodeWidth(15) .nodePadding(10) .extent([[1, 5], [width - 1, height - 5]]); // Applies it to the data. We make a copy of the nodes and links objects // so as to avoid mutating the original. const {nodes, links} = sankey({ nodes: data.nodes.map(d => Object.assign({}, d)), links: data.links.map(d => Object.assign({}, d)) }); // Defines a color scale. const color = d3.scaleOrdinal(d3.schemeCategory10); // Creates the rects that represent the nodes. const rect = svg.append("g") .attr("stroke", "#000") .selectAll() .data(nodes) .join("rect") .attr("x", d => d.x0) .attr("y", d => d.y0) .attr("height", d => d.y1 - d.y0) .attr("width", d => d.x1 - d.x0) .attr("fill", d => color(d.category)); // Adds a title on the nodes. rect.append("title") .text(d => `${d.name}\n${format(d.value)} TWh`); // Creates the paths that represent the links. const link = svg.append("g") .attr("fill", "none") .attr("stroke-opacity", 0.5) .selectAll() .data(links) .join("g") .style("mix-blend-mode", "multiply"); // Creates a gradient, if necessary, for the source-target color option. if (linkColor === "source-target") { const gradient = link.append("linearGradient") .attr("id", d => (d.uid = DOM.uid("link")).id) .attr("gradientUnits", "userSpaceOnUse") .attr("x1", d => d.source.x1) .attr("x2", d => d.target.x0); gradient.append("stop") .attr("offset", "0%") .attr("stop-color", d => color(d.source.category)); gradient.append("stop") .attr("offset", "100%") .attr("stop-color", d => color(d.target.category)); } link.append("path") .attr("d", d3.sankeyLinkHorizontal()) .attr("stroke", linkColor === "source-target" ? (d) => d.uid : linkColor === "source" ? (d) => color(d.source.category) : linkColor === "target" ? (d) => color(d.target.category) : linkColor) .attr("stroke-width", d => Math.max(1, d.width)); link.append("title") .text(d => `${d.source.name} → ${d.target.name}\n${format(d.value)} TWh`); // Adds labels on the nodes. svg.append("g") .selectAll() .data(nodes) .join("text") .attr("x", d => d.x0 < width / 2 ? d.x1 + 6 : d.x0 - 6) .attr("y", d => (d.y1 + d.y0) / 2) .attr("dy", "0.35em") .attr("text-anchor", d => d.x0 < width / 2 ? "start" : "end") .text(d => d.name); return svg.node(); }4a:[{"id":"d6774e9422bd72369f195a30d3a6b33ff9d41676cff4d89c93511e1a458efb3cfd16cbb7ce3fecdd8dd2466121e10c9bfe57fd73c7520bf358d352a92b898614","href":"https://static.observableusercontent.com/files/d6774e9422bd72369f195a30d3a6b33ff9d41676cff4d89c93511e1a458efb3cfd16cbb7ce3fecdd8dd2466121e10c9bfe57fd73c7520bf358d352a92b898614","name":"energy.csv","type":"text/csv","lastModified":1746875957863.663,"size":2267}] 29:{"id":"92490f93f01450ad","slug":null,"title":"Sankey diagram","thumbnail":"afc325259d64969c985ce11808a28b0a1528b00c3c9185266b3a8aaba21e2796","access_level":"public","create_time":"$D2025-05-10T11:19:17.863Z","update_time":"$D2025-05-10T11:19:17.863Z","view_time":null,"first_public_time":"$D2025-05-10T11:19:17.863Z","has_unpublished_edits":null,"fork":{"id":"3ecaa4aaa61dc833","slug":"sankey/2","title":"Sankey diagram","owner":{"id":"863951e3ebe4c0ae","login":"d3","name":"D3"}},"stars":0,"starred":false,"owner":{"type":"team","id":"359c978afcb2bfc7","login":"bradfordjohnson","name":"Ford Johnson","avatar_url":"https://avatars-next.observableusercontent.com/84b84ae9d388a4ee2f161b86e6d14a038818679ab572b195e256b123a7555026","tier":"free_2026","bio":"Data Analyst","following":false},"version":339,"publish_version":null,"role":null,"authored":false,"authors":[{"type":"individual","id":"db0515f0b74f4453","login":"bradfordjohnson","name":"Ford Johnson","avatar_url":"https://avatars-next.observableusercontent.com/731a7f6cd4d9429a3855c9fd571c0cac81626b28c7d3ed2bc07eab7523607892","tier":null,"bio":"Data Analyst | Visualization Designer","following":false}],"members":[{"type":"individual","id":"db0515f0b74f4453","login":"bradfordjohnson","name":"Ford Johnson","avatar_url":"https://avatars-next.observableusercontent.com/731a7f6cd4d9429a3855c9fd571c0cac81626b28c7d3ed2bc07eab7523607892","tier":null,"role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"lapsed":null,"subscribed":null,"forks":0,"collection":null,"type":"notebook","body":{"titling":"auto","title":"Sankey diagram","cells":[{"id":0,"value":"

Sankey diagram

D3 › Gallery

\n\n# Sankey diagram\n\nThis [Sankey diagram](https://github.com/d3/d3-sankey) visualizes the flow of energy: *supplies* are on the left, and *demands* are on the right. Links show how varying amounts of energy are converted or transmitted before being consumed or lost. Data: [Department of Energy & Climate Change](http://www.decc.gov.uk/en/content/cms/tackling/2050/calculator_on/calculator_on.aspx) via [Tom Counsell](https://tamc.github.io/Sankey/)","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":160,"value":"viewof linkColor = Inputs.select(new Map([\n [\"static\", \"#aaa\"],\n [\"source-target\", \"source-target\"],\n [\"source\", \"source\"],\n [\"target\", \"target\"],\n]), {\n value: new URLSearchParams(html``.search).get(\"color\") || \"source-target\",\n label: \"Link color\"\n})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":181,"value":"viewof nodeAlign = Inputs.select(new Map([[\"left\", \"sankeyLeft\"], [\"right\", \"sankeyRight\"], [\"center\", \"sankeyCenter\"], [\"justify\", \"sankeyJustify\"]]), {\n value: \"sankeyJustify\",\n label: \"Node alignment\"\n})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":11,"value":"$49","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":249,"value":"data = {\n const links = await FileAttachment(\"energy.csv\").csv({typed: true});\n const nodes = Array.from(new Set(links.flatMap(l => [l.source, l.target])), name => ({name, category: name.replace(/ .*/, \"\")}));\n return {nodes, links};\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":7,"value":"// [d3-sankey](https://github.com/d3/d3-sankey) is not part of the D3 bundle\nd3 = require(\"d3@7\", \"d3-sankey@0.12\")","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W4a","stdlib":"1"}} 24:null