Public
Edited
Apr 26, 2023
Insert cell
Insert cell
Insert cell
idiom1 = StackedAreaChart(idiom1Data, {
x: d => new Date(d.year, 0, 1),
y: d => d.h1b_count,
z: d => d.CS_related,
xType: d3.scaleTime,
xFormat: d3.format(".0f"),
xDomain: [new Date(2016, 12, 1), new Date(2022, 7, 1)],
yLabel: "↑ H1B Petitions",
yFormat: d3.format("s"),
width: 800,
height: 500
})
Insert cell
// Copyright 2021 Observable, Inc.
// Released under the ISC license.
// Modified from https://observablehq.com/@d3/stacked-area-chart
function StackedAreaChart(data, {
x = ([x]) => x, // given d in data, returns the (ordinal) x-value
y = ([, y]) => y, // given d in data, returns the (quantitative) y-value
z = () => 1, // given d in data, returns the (categorical) z-value
marginTop = 20, // top margin, in pixels
marginRight = 30, // 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
xType = d3.scaleUtc, // type of x-scale
xDomain, // [xmin, xmax]
xRange = [marginLeft, width - marginRight], // [left, right]
yType = d3.scaleLinear, // type of y-scale
yDomain, // [ymin, ymax]
yRange = [height - marginBottom, marginTop], // [bottom, top]
zDomain, // array of z-values
offset = d3.stackOffsetDiverging, // stack offset method
order = d3.stackOrderNone, // stack order method
xFormat, // a format specifier string for the x-axis
yFormat, // a format specifier for the y-axis
yLabel, // a label for the y-axis
colors = d3.schemeTableau10, // array of colors for z
yRightFormat = ".0%", // a format specifier for the right y-axis
yRightLabel, // a label for the right y-axis
} = {}) {
// Compute values.
const X = d3.map(data, x);
const Y = d3.map(data, y);
const Z = d3.map(data, z);

// Compute default x- and z-domains, and unique the z-domain.
if (xDomain === undefined) xDomain = d3.extent(X);
if (zDomain === undefined) zDomain = Z;
zDomain = new d3.InternSet(zDomain); // create a set that supports Date object as a key

// Omit any data not present in the z-domain.
const I = d3.range(X.length).filter(i => zDomain.has(Z[i]));

console.log({X, Y, Z, I});

// Compute a nested array of series where each series is [[y1, y2], [y1, y2],
// [y1, y2], …] representing the y-extent of each stacked rect. In addition,
// each tuple has an i (index) property so that we can refer back to the
// original data point (data[i]). This code assumes that there is only one
// data point for a given unique x- and z-value.
const series = d3.stack()
.keys(zDomain)
.value(([x, I], z) => Y[I.get(z)])
.order(order)
.offset(offset)
(d3.rollup(I, ([i]) => i, i => X[i], i => Z[i]))
.map(s => s.map(d => Object.assign(d, {i: d.data[1].get(s.key)})));

// Compute the default y-domain. Note: diverging stacks can be negative.
if (yDomain === undefined) yDomain = d3.extent(series.flat(2));

// Construct scales and axes.
const xScale = xType(xDomain, xRange);
const yScale = yType(yDomain, yRange);
const color = d3.scaleOrdinal(zDomain, colors);
// const xAxis = d3.axisBottom(xScale).ticks(width / 80, xFormat).tickSizeOuter(0);
const xAxis = d3.axisBottom(xScale).ticks(d3.timeYear.every(1));
const yAxis = d3.axisLeft(yScale).ticks(height / 50, yFormat);

const area = d3.area()
.x(({i}) => xScale(X[i]))
.y0(([y1]) => yScale(y1))
.y1(([, y2]) => yScale(y2));

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));

svg.append("g")
.selectAll("path")
.data(series)
.join("path")
.attr("fill", ([{i}]) => color(Z[i]))
.attr("d", area)
.append("title")
.text(([{i}]) => Z[i]);

svg.append("g")
.attr("transform", `translate(0,${height - marginBottom})`)
.call(xAxis);

const L = I.map(i => (Y[i]+Y[i+1])*0.5) // helper array, only 0,2,4,6,8,10 indices are meaningful here
const line = d3.line()
.curve(d3.curveLinear)
.x(i => xScale(X[i]))
.y(i => yScale(L[i]));
svg.append("path")
.attr("fill", "none")
.attr("stroke", "#ce5e5b")
.attr("stroke-width", 1.5)
.attr("stroke-linecap", "round")
.attr("stroke-linejoin", "round")
.attr("stroke-opacity", 1)
.attr("d", line([0,2,4,6,8,10]));

return Object.assign(svg.node(), {scales: {color}});
}
Insert cell
idiom1Data = FileAttachment("idiom1-data.csv").csv({typed: true})
Insert cell
import {Swatches} from "@d3/color-legend"
Insert cell

One platform to build and deploy the best data apps

Experiment and prototype by building visualizations in live JavaScript notebooks. Collaborate with your team and decide which concepts to build out.
Use Observable Framework to build data apps locally. Use data loaders to build in any language or library, including Python, SQL, and R.
Seamlessly deploy to Observable. Test before you ship, use automatic deploy-on-commit, and ensure your projects are always up-to-date.
Learn more