chart = BeeswarmChart(cars, {
x: d => d.Weight_in_lbs,
xLabel: "Weight (lbs.) →",
title: d => d.Name,
width
})
cars = FileAttachment("cars.csv").csv({typed: true})
// Copyright 2021 Observable, Inc.
// Released under the ISC license.
// https://observablehq.com/@d3/mirrored-beeswarm
function BeeswarmChart(data, {
value = d => d, // convience alias for x
label, // convenience alias for xLabel
domain, // convenience alias for xDomain
x = value, // given d in data, returns the quantitative x value
title = null, // given d in data, returns the title
radius = 3, // (fixed) radius of the circles
padding = 1.5, // (fixed) padding between the circles
marginTop = 10, // top margin, in pixels
marginRight = 20, // right margin, in pixels
marginBottom = 30, // bottom margin, in pixels
marginLeft = 20, // left margin, in pixels
width = 640, // outer width, in pixels
height, // outer height, in pixels
xLabel = label, // a label for the x-axis
xDomain = domain, // [xmin, xmax]
xRange = [marginLeft, width - marginRight] // [left, right]
} = {}) {
// Compute values.
const X = d3.map(data, x);
const T = title == null ? null : d3.map(data, title);
// Compute which data points are considered defined.
const I = d3.range(X.length).filter(i => !isNaN(X[i]));
// Compute default domains.
if (xDomain === undefined) xDomain = d3.extent(X);
// Construct scales and axes.
const xScale = d3.scaleLinear(xDomain, xRange);
const xAxis = d3.axisBottom(xScale).tickSizeOuter(0);
// Compute the y-positions.
const Y = dodge(I.map(i => xScale(X[i])), radius * 2 + padding);
// Compute the default height;
if (height === undefined) height = (d3.max(Y, Math.abs) + radius + padding) * 2 + marginTop + marginBottom;
// Given an array of x-values and a separation radius, returns an array of y-values.
function dodge(X, radius) {
const Y = new Float64Array(X.length);
const radius2 = radius ** 2;
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) {
const ai = a.index;
if (radius2 - epsilon > (X[ai] - x) ** 2 + (Y[ai] - y) ** 2) return true;
a = a.next;
}
return false;
}
// Place each circle sequentially.
for (const bi of d3.range(X.length).sort((i, j) => X[i] - X[j])) {
// Remove circles from the queue that can’t intersect the new circle b.
while (head && X[head.index] < X[bi] - radius2) head = head.next;
// Choose the minimum non-intersecting tangent.
if (intersects(X[bi], Y[bi] = 0)) {
let a = head;
Y[bi] = Infinity;
do {
const ai = a.index;
let y1 = Y[ai] + Math.sqrt(radius2 - (X[ai] - X[bi]) ** 2);
let y2 = Y[ai] - Math.sqrt(radius2 - (X[ai] - X[bi]) ** 2);
if (Math.abs(y1) < Math.abs(Y[bi]) && !intersects(X[bi], y1)) Y[bi] = y1;
if (Math.abs(y2) < Math.abs(Y[bi]) && !intersects(X[bi], y2)) Y[bi] = y2;
a = a.next;
} while (a);
}
// Add b to the queue.
const b = {index: bi, next: null};
if (head === null) head = tail = b;
else tail = tail.next = b;
}
return Y;
}
const svg = d3.create("svg")
.attr("width", width)
.attr("height", height)
.attr("viewBox", [0, 0, width, height])
.attr("style", "max-width: 100%; height: auto; height: intrinsic;");
svg.append("g")
.attr("transform", `translate(0,${height - marginBottom})`)
.call(xAxis)
.call(g => g.append("text")
.attr("x", width)
.attr("y", marginBottom - 4)
.attr("fill", "currentColor")
.attr("text-anchor", "end")
.text(xLabel));
const dot = svg.append("g")
.selectAll("circle")
.data(I)
.join("circle")
.attr("cx", i => xScale(X[i]))
.attr("cy", i => (marginTop + height - marginBottom) / 2 + Y[i])
.attr("r", radius);
if (T) dot.append("title")
.text(i => T[i]);
return svg.node();
}
import {howto} from "@d3/example-components"
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