31:T4d7,viewof graph = { const form = html``; const graphs = {1: graph1, 2: graph2, 3: graph3}; const timeout = setInterval(() => { form.value = graphs[form.radio.value = (+form.radio.value) % 3 + 1]; form.dispatchEvent(new CustomEvent("input")); }, 2000); form.onchange = () => form.dispatchEvent(new CustomEvent("input")); // Safari form.oninput = event => { if (event.isTrusted) clearInterval(timeout), form.onchange = null; form.value = graphs[form.radio.value]; }; form.value = graphs[form.radio.value]; invalidation.then(() => clearInterval(timeout)); return form; }32:T6e8,chart = { const svg = d3.create("svg") .attr("width", width) .attr("height", height) .attr("viewBox", [-width / 2, -height / 2, width, height]); const simulation = d3.forceSimulation() .force("charge", d3.forceManyBody().strength(-1000)) .force("link", d3.forceLink().id(d => d.id).distance(200)) .force("x", d3.forceX()) .force("y", d3.forceY()) .on("tick", ticked); let link = svg.append("g") .attr("stroke", "#000") .attr("stroke-width", 1.5) .selectAll("line"); let node = svg.append("g") .attr("stroke", "#fff") .attr("stroke-width", 1.5) .selectAll("circle"); function ticked() { node.attr("cx", d => d.x) .attr("cy", d => d.y) link.attr("x1", d => d.source.x) .attr("y1", d => d.source.y) .attr("x2", d => d.target.x) .attr("y2", d => d.target.y); } // Terminate the force layout when this cell re-runs. invalidation.then(() => simulation.stop()); return Object.assign(svg.node(), { update({nodes, links}) { // Make a shallow copy to protect against mutation, while // recycling old nodes to preserve position and velocity. const old = new Map(node.data().map(d => [d.id, d])); nodes = nodes.map(d => Object.assign(old.get(d.id) || {}, d)); links = links.map(d => Object.assign({}, d)); simulation.nodes(nodes); simulation.force("link").links(links); simulation.alpha(1).restart(); node = node .data(nodes, d => d.id) .join(enter => enter.append("circle") .attr("r", 8) .attr("fill", d => color(d.id))); link = link .data(links, d => `${d.source.id}\t${d.target.id}`) .join("line"); } }); }33:[] 2f:{"title":"Modifying a Force-Directed Graph","cells":[{"id":0,"value":"md`# Modifying a Force-Directed Graph\n\nThis notebook demonstrates how to update a live [force-directed graph](/@d3/force-directed-graph). We use [*selection*.join](/@d3/selection-join) with a key function to add and remove elements as the graph changes; and we update the simulation’s nodes and links before restarting.`","pinned":false,"hidden":false,"mode":"ojs"},{"id":15,"value":"$31","pinned":false,"hidden":false,"mode":"ojs"},{"id":25,"value":"$32","pinned":true,"hidden":false,"mode":"ojs"},{"id":29,"value":"update = chart.update(graph)","pinned":true,"hidden":false,"mode":"ojs"},{"id":5,"value":"graph1 = ({\n nodes: [\n {id: \"a\"},\n {id: \"b\"},\n {id: \"c\"}\n ],\n links: []\n})","pinned":true,"hidden":false,"mode":"ojs"},{"id":7,"value":"graph2 = ({\n nodes: [\n {id: \"a\"},\n {id: \"b\"},\n {id: \"c\"}\n ],\n links: [\n {source: \"a\", target: \"b\"},\n {source: \"b\", target: \"c\"},\n {source: \"c\", target: \"a\"}\n ]\n})","pinned":true,"hidden":false,"mode":"ojs"},{"id":10,"value":"graph3 = ({\n nodes: [\n {id: \"a\"},\n {id: \"b\"}\n ],\n links: [\n {source: \"a\", target: \"b\"}\n ]\n})","pinned":true,"hidden":false,"mode":"ojs"},{"id":33,"value":"color = d3.scaleOrdinal(d3.schemeTableau10)","pinned":true,"hidden":false,"mode":"ojs"},{"id":21,"value":"height = 400","pinned":true,"hidden":false,"mode":"ojs"}],"files":"$W33","stdlib":"1","titling":"auto"}