chart = {
var nodes = [
{name: "Topic 4"},
{name: "mental"},
{name: "people"},
{name: "drug"},
{name: "ill"},
{name: "health"},
{name: "problem"},
{name: "use"},
{name: "issue"},
{name: "cause"},
{name: "suicide"},
{name: "depression"},
{name: "gun"},
{name: "violence"}
];
var links = [
{source: "mental", target: "Topic 4" },
{source: "people", target: "Topic 4" },
{source: "drug", target: "Topic 4" },
{source: "ill", target: "Topic 4" },
{source: "health", target: "Topic 4" },
{source: "problem", target: "Topic 4" },
{source: "use", target: "Topic 4" },
{source: "issue", target: "Topic 4" },
{source: "cause", target: "Topic 4" },
{source: "suicide", target: "Topic 4" },
{source: "depression", target: "Topic 4" },
{source: "gun", target: "Topic 4" },
{source: "violence", target: "Topic 4" }
];
const simulation = d3.forceSimulation(nodes)
.force("link", d3.forceLink(links).id(d => d.name))
.force("charge", d3.forceManyBody())
.force("center", d3.forceCenter(width / 2, height / 2));
const svg = d3.create("svg")
.attr("viewBox", [0, 0, width, height]);
const link = svg.append("g")
.attr("stroke", "#999")
.attr("stroke-opacity", 0.6)
.selectAll("line")
.data(links)
.join("line")
.attr("stroke-width", d => Math.sqrt(d.value));
const node = svg.append("g")
.attr("stroke", "#fff")
.attr("stroke-width", 1.5)
.selectAll("circle")
.data(nodes)
.join("circle")
.attr("r", 8)
.attr("fill", "red")
.call(drag(simulation));
node.append("title")
.text(d => d.name);
node.append("text")
.attr("dx", 12)
.attr("dy", ".35em")
.text(function(d) { return d.name });
simulation.on("tick", () => {
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);
node
.attr("cx", d => d.x)
.attr("cy", d => d.y);
});
invalidation.then(() => simulation.stop());
return svg.node();
}