chart = GroupedBarChart(stateages, {
x: d => d.state,
y: d => d.population / 1e6,
z: d => d.age,
xDomain: d3.groupSort(stateages, D => d3.sum(D, d => -d.population), d => d.state).slice(0, 6), // top 6
yLabel: "↑ Population (millions)",
zDomain: ages,
colors: d3.schemeSpectral[ages.length],
width,
height: 500
})
states = FileAttachment("us-population-state-age.csv").csv({typed: true})
ages = states.columns.slice(1)
stateages = ages.flatMap(age => states.map(d => ({state: d.name, age, population: d[age]}))) // pivot longer
// Copyright 2021 Observable, Inc.
// Released under the ISC license.
// https://observablehq.com/@d3/grouped-bar-chart
function GroupedBarChart(data, {
x = (d, i) => i, // given d in data, returns the (ordinal) x-value
y = d => d, // given d in data, returns the (quantitative) y-value
z = () => 1, // given d in data, returns the (categorical) z-value
title, // given d in data, returns the title text
marginTop = 30, // top margin, in pixels
marginRight = 0, // right margin, in pixels
marginBottom = 30, // bottom margin, in pixels
marginLeft = 40, // left margin, in pixels
width = 640, // outer width, in pixels
height = 400, // outer height, in pixels
xDomain, // array of x-values
xRange = [marginLeft, width - marginRight], // [xmin, xmax]
xPadding = 0.1, // amount of x-range to reserve to separate groups
yType = d3.scaleLinear, // type of y-scale
yDomain, // [ymin, ymax]
yRange = [height - marginBottom, marginTop], // [ymin, ymax]
zDomain, // array of z-values
zPadding = 0.05, // amount of x-range to reserve to separate bars
yFormat, // a format specifier string for the y-axis
yLabel, // a label for the y-axis
colors = d3.schemeTableau10, // array of colors
} = {}) {
// Compute values.
const X = d3.map(data, x);
const Y = d3.map(data, y);
const Z = d3.map(data, z);
// Compute default domains, and unique the x- and z-domains.
if (xDomain === undefined) xDomain = X;
if (yDomain === undefined) yDomain = [0, d3.max(Y)];
if (zDomain === undefined) zDomain = Z;
xDomain = new d3.InternSet(xDomain);
zDomain = new d3.InternSet(zDomain);
// Omit any data not present in both the x- and z-domain.
const I = d3.range(X.length).filter(i => xDomain.has(X[i]) && zDomain.has(Z[i]));
// Construct scales, axes, and formats.
const xScale = d3.scaleBand(xDomain, xRange).paddingInner(xPadding);
const xzScale = d3.scaleBand(zDomain, [0, xScale.bandwidth()]).padding(zPadding);
const yScale = yType(yDomain, yRange);
const zScale = d3.scaleOrdinal(zDomain, colors);
const xAxis = d3.axisBottom(xScale).tickSizeOuter(0);
const yAxis = d3.axisLeft(yScale).ticks(height / 60, yFormat);
// Compute titles.
if (title === undefined) {
const formatValue = yScale.tickFormat(100, yFormat);
title = i => `${X[i]}\n${Z[i]}\n${formatValue(Y[i])}`;
} else {
const O = d3.map(data, d => d);
const T = title;
title = i => T(O[i], i, data);
}
const svg = d3.create("svg")
.attr("width", width)
.attr("height", height)
.attr("viewBox", [0, 0, width, height])
.attr("style", "max-width: 100%; height: auto; height: intrinsic;");
svg.append("g")
.attr("transform", `translate(${marginLeft},0)`)
.call(yAxis)
.call(g => g.select(".domain").remove())
.call(g => g.selectAll(".tick line").clone()
.attr("x2", width - marginLeft - marginRight)
.attr("stroke-opacity", 0.1))
.call(g => g.append("text")
.attr("x", -marginLeft)
.attr("y", 10)
.attr("fill", "currentColor")
.attr("text-anchor", "start")
.text(yLabel));
const bar = svg.append("g")
.selectAll("rect")
.data(I)
.join("rect")
.attr("x", i => xScale(X[i]) + xzScale(Z[i]))
.attr("y", i => yScale(Y[i]))
.attr("width", xzScale.bandwidth())
.attr("height", i => yScale(0) - yScale(Y[i]))
.attr("fill", i => zScale(Z[i]));
if (title) bar.append("title")
.text(title);
svg.append("g")
.attr("transform", `translate(0,${height - marginBottom})`)
.call(xAxis);
return Object.assign(svg.node(), {scales: {color: zScale}});
}
import {Legend, Swatches} from "@d3/color-legend"
import {howto, altplot} from "@d3/example-components"
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