chart = {
// Declare the chart dimensions and margins.
const width = 928;
const height = 160;
const marginRight = 20;
const marginLeft = 20;
const marginBottom = 20;
// Dot size and padding.
const radius = 3;
const padding = 1.5;
// Declare the horizontal (x) encoding.
const x = d3.scaleLinear()
.domain(d3.extent(cars, d => d["weight (lb)"]))
.range([marginLeft, width - marginRight]);
const svg = d3.create("svg")
.attr("width", width)
.attr("height", height)
.attr("viewBox", [0, 0, width, height])
.attr("style", "max-width: 100%; height: auto;");
// Add the x axis.
svg.append("g")
.attr("transform", `translate(0,${height - marginBottom})`)
.call(d3.axisBottom(x).tickSizeOuter(0));
// Add a dot for each data point, positioned with the dodge function.
svg.append("g")
.selectAll("circle")
.data(dodge(cars, {radius: radius * 2 + padding, x: d => x(d["weight (lb)"])}))
.join("circle")
.attr("cx", d => d.x)
.attr("cy", d => height / 2 - radius - padding - d.y)
.attr("r", radius)
.append("title")
.text(d => d.data.name);
return svg.node();
}
dodge = (data, {radius, x}) => {
const radius2 = radius ** 2;
const circles = data.map(d => ({x: x(d), data: d})).sort((a, b) => a.x - b.x);
const epsilon = 1e-3;
let head = null, tail = null;
// Returns true if circle ⟨x,y⟩ intersects with any circle in the queue.
function intersects(x, y) {
let a = head;
while (a) {
if (radius2 - epsilon > (a.x - x) ** 2 + (a.y - y) ** 2) {
return true;
}
a = a.next;
}
return false;
}
// Place each circle sequentially.
for (const b of circles) {
// Remove circles from the queue that can’t intersect the new circle b.
while (head && head.x < b.x - radius2) head = head.next;
// Choose the minimum non-intersecting tangent.
if (intersects(b.x, b.y = 0)) {
let a = head;
b.y = Infinity;
do {
let y1 = a.y + Math.sqrt(radius2 - (a.x - b.x) ** 2);
let y2 = a.y - Math.sqrt(radius2 - (a.x - b.x) ** 2);
if (Math.abs(y1) < Math.abs(b.y) && !intersects(b.x, y1)) b.y = y1;
if (Math.abs(y2) < Math.abs(b.y) && !intersects(b.x, y2)) b.y = y2;
a = a.next;
} while (a);
}
// Add b to the queue.
b.next = null;
if (head === null) head = tail = b;
else tail = tail.next = b;
}
return circles;
}
Plot.plot({
height: 165,
x: {line: true},
marks: [
Plot.dotX(cars, Plot.dodgeY({
x: "weight (lb)",
sort: "weight (lb)",
title: "name",
fill: "currentColor",
anchor: "middle"
}))
]
})
cars
Purpose-built for displays of data
Observable is your go-to platform for exploring data and creating expressive data visualizations. Use reactive JavaScript notebooks for prototyping and a collaborative canvas for visual data exploration and dashboard creation.
