viewof focus = {
const svg = d3.create("svg")
.attr("viewBox", [0, 0, width, focusHeight])
.style("display", "block");
const brush = d3.brushX()
.extent([[margin.left, 0.5], [width - margin.right, focusHeight - margin.bottom + 0.5]])
.on("brush", brushed)
.on("end", brushended);
const defaultSelection = [x(d3.utcYear.offset(x.domain()[1], -1)), x.range()[1]];
svg.append("g")
.call(xAxis, x, focusHeight);
svg.append("path")
.datum(data)
.attr("fill", "steelblue")
.attr("d", area(x, y.copy().range([focusHeight - margin.bottom, 4])));
const gb = svg.append("g")
.call(brush)
.call(brush.move, defaultSelection);
function brushed({selection}) {
if (selection) {
svg.property("value", selection.map(x.invert, x).map(d3.utcDay.round));
svg.dispatch("input");
}
}
function brushended({selection}) {
if (!selection) {
gb.call(brush.move, defaultSelection);
}
}
return svg.node();
}
update = {
const [minX, maxX] = focus;
const maxY = d3.max(data, d => minX <= d.date && d.date <= maxX ? d.value : NaN);
chart.update(x.copy().domain(focus), y.copy().domain([0, maxY]));
}
data = Object.assign(d3.csvParse(await FileAttachment("aapl.csv").text(), d3.autoType).map(({date, close}) => ({date, value: close})), {y: "↑ Close $"})
area = (x, y) => d3.area()
.defined(d => !isNaN(d.value))
.x(d => x(d.date))
.y0(y(0))
.y1(d => y(d.value))
x = d3.scaleUtc()
.domain(d3.extent(data, d => d.date))
.range([margin.left, width - margin.right])
y = d3.scaleLinear()
.domain([0, d3.max(data, d => d.value)])
.range([height - margin.bottom, margin.top])
xAxis = (g, x, height) => g
.attr("transform", `translate(0,${height - margin.bottom})`)
.call(d3.axisBottom(x).ticks(width / 80).tickSizeOuter(0))
yAxis = (g, y, title) => g
.attr("transform", `translate(${margin.left},0)`)
.call(d3.axisLeft(y))
.call(g => g.select(".domain").remove())
.call(g => g.selectAll(".title").data([title]).join("text")
.attr("class", "title")
.attr("x", -margin.left)
.attr("y", 10)
.attr("fill", "currentColor")
.attr("text-anchor", "start")
.text(title))
margin = ({top: 20, right: 20, bottom: 30, left: 40})
height = 440
focusHeight = 100
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.
