chart = {
// Specify the chart’s dimensions.
const width = 928;
const height = 500;
const marginTop = 10;
const marginRight = 10;
const marginBottom = 20;
const marginLeft = 40;
// Determine the series that need to be stacked.
const series = d3
.stack()
.keys(d3.union(data.map((d) => d.age))) // distinct series keys, in input order
.value(([, D], key) => D.get(key).population)(
// get value for each series key and stack
d3.index(
data,
(d) => d.state,
(d) => d.age
)
); // group by stack then series key
// Prepare the scales for positional and color encodings.
const x = d3
.scaleBand()
.domain(
d3.groupSort(
data,
(D) => -d3.sum(D, (d) => d.population),
(d) => d.state
)
)
.range([marginLeft, width - marginRight])
.padding(0.1);
const y = d3
.scaleLinear()
.domain([0, d3.max(series, (d) => d3.max(d, (d) => d[1]))])
.rangeRound([height - marginBottom, marginTop]);
const color = d3
.scaleOrdinal()
.domain(series.map((d) => d.key))
.range(d3.schemeSpectral[series.length])
.unknown("#ccc");
// A function to format the value in the tooltip.
const formatValue = (x) => (isNaN(x) ? "N/A" : x.toLocaleString("en"));
// Create the SVG container.
const svg = d3
.create("svg")
.attr("width", width)
.attr("height", height)
.attr("viewBox", [0, 0, width, height])
.attr("style", "max-width: 100%; height: auto;");
// Append a group for each series, and a rect for each element in the series.
svg
.append("g")
.selectAll()
.data(series)
.join("g")
.attr("fill", (d) => color(d.key))
.selectAll("rect")
.data((D) => D.map((d) => ((d.key = D.key), d)))
.join("rect")
.attr("x", (d) => x(d.data[0]))
.attr("y", (d) => y(d[1]))
.attr("height", (d) => y(d[0]) - y(d[1]))
.attr("width", x.bandwidth())
.append("title")
.text(
(d) =>
`${d.data[0]} ${d.key}\n${formatValue(d.data[1].get(d.key).population)}`
);
// Append the horizontal axis.
svg
.append("g")
.attr("transform", `translate(0,${height - marginBottom})`)
.call(d3.axisBottom(x).tickSizeOuter(0))
.call((g) => g.selectAll(".domain").remove());
// Append the vertical axis.
svg
.append("g")
.attr("transform", `translate(${marginLeft},0)`)
.call(d3.axisLeft(y).ticks(null, "s"))
.call((g) => g.selectAll(".domain").remove());
// Return the chart with the color scale as a property (for the legend).
return Object.assign(svg.node(), { scales: { color } });
}
data = {
const data = await FileAttachment("us-population-state-age.csv").csv({typed: true});
return data.columns.slice(1).flatMap((age) => data.map((d) => ({state: d.name, age, population: d[age]})));
}
import {legend} from "@d3/color-legend"
Plot.plot({
y: {transform: (d) => d / 1e6},
color: {scheme: "spectral"},
marks: [Plot.barY(data, {x: "state", y: "population", fill: "age", sort: {color: null, x: "-y"}})]
})
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.
