chart = LineChart(aapl, {
x: d => d.date,
y: d => d.close,
yLabel: "↑ Daily close ($)",
width,
height: 500,
color: "steelblue"
})
aapl = FileAttachment("aapl.csv").csv({typed: true})
focus = Generators.input(chart) // or say viewof focus = LineChart(…)
// Copyright 2021 Observable, Inc.
// Released under the ISC license.
// https://observablehq.com/@d3/line-with-tooltip
function LineChart(data, {
x = ([x]) => x, // given d in data, returns the (temporal) x-value
y = ([, y]) => y, // given d in data, returns the (quantitative) y-value
title, // given d in data, returns the title text
defined, // for gaps in data
curve = d3.curveLinear, // method of interpolation between points
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]
color = "currentColor", // stroke color of line
strokeWidth = 1.5, // stroke width of line, in pixels
strokeLinejoin = "round", // stroke line join of line
strokeLinecap = "round", // stroke line cap of line
yFormat, // a format specifier string for the y-axis
yLabel, // a label for the y-axis
} = {}) {
// Compute values.
const X = d3.map(data, x);
const Y = d3.map(data, y);
const O = d3.map(data, d => d);
const I = d3.map(data, (_, i) => i);
// Compute which data points are considered defined.
if (defined === undefined) defined = (d, i) => !isNaN(X[i]) && !isNaN(Y[i]);
const D = d3.map(data, defined);
// Compute default domains.
if (xDomain === undefined) xDomain = d3.extent(X);
if (yDomain === undefined) yDomain = [0, d3.max(Y)];
// Construct scales and axes.
const xScale = xType(xDomain, xRange);
const yScale = yType(yDomain, yRange);
const xAxis = d3.axisBottom(xScale).ticks(width / 80).tickSizeOuter(0);
const yAxis = d3.axisLeft(yScale).ticks(height / 40, yFormat);
// Compute titles.
if (title === undefined) {
const formatDate = xScale.tickFormat(null, "%b %-d, %Y");
const formatValue = yScale.tickFormat(100, yFormat);
title = i => `${formatDate(X[i])}\n${formatValue(Y[i])}`;
} else {
const O = d3.map(data, d => d);
const T = title;
title = i => T(O[i], i, data);
}
// Construct a line generator.
const line = d3.line()
.defined(i => D[i])
.curve(curve)
.x(i => xScale(X[i]))
.y(i => yScale(Y[i]));
const svg = d3.create("svg")
.attr("width", width)
.attr("height", height)
.attr("viewBox", [0, 0, width, height])
.attr("style", "max-width: 100%; height: auto; height: intrinsic;")
.attr("font-family", "sans-serif")
.attr("font-size", 10)
.style("-webkit-tap-highlight-color", "transparent")
.style("overflow", "visible")
.on("pointerenter pointermove", pointermoved)
.on("pointerleave", pointerleft)
.on("touchstart", event => event.preventDefault());
svg.append("g")
.attr("transform", `translate(0,${height - marginBottom})`)
.call(xAxis);
svg.append("g")
.attr("transform", `translate(${marginLeft},0)`)
.call(yAxis)
.call(g => g.select(".domain").remove())
.call(g => g.selectAll(".tick line").clone()
.attr("x2", width - marginLeft - marginRight)
.attr("stroke-opacity", 0.1))
.call(g => g.append("text")
.attr("x", -marginLeft)
.attr("y", 10)
.attr("fill", "currentColor")
.attr("text-anchor", "start")
.text(yLabel));
svg.append("path")
.attr("fill", "none")
.attr("stroke", color)
.attr("stroke-width", strokeWidth)
.attr("stroke-linejoin", strokeLinejoin)
.attr("stroke-linecap", strokeLinecap)
.attr("d", line(I));
const tooltip = svg.append("g")
.style("pointer-events", "none");
function pointermoved(event) {
const i = d3.bisectCenter(X, xScale.invert(d3.pointer(event)[0]));
tooltip.style("display", null);
tooltip.attr("transform", `translate(${xScale(X[i])},${yScale(Y[i])})`);
const path = tooltip.selectAll("path")
.data([,])
.join("path")
.attr("fill", "white")
.attr("stroke", "black");
const text = tooltip.selectAll("text")
.data([,])
.join("text")
.call(text => text
.selectAll("tspan")
.data(`${title(i)}`.split(/\n/))
.join("tspan")
.attr("x", 0)
.attr("y", (_, i) => `${i * 1.1}em`)
.attr("font-weight", (_, i) => i ? null : "bold")
.text(d => d));
const {x, y, width: w, height: h} = text.node().getBBox();
text.attr("transform", `translate(${-w / 2},${15 - y})`);
path.attr("d", `M${-w / 2 - 10},5H-5l5,-5l5,5H${w / 2 + 10}v${h + 20}h-${w + 20}z`);
svg.property("value", O[i]).dispatch("input", {bubbles: true});
}
function pointerleft() {
tooltip.style("display", "none");
svg.node().value = null;
svg.dispatch("input", {bubbles: true});
}
return Object.assign(svg.node(), {value: null});
}
import {howto} from "@d3/example-components"
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