Maps, Data, Viz, UX, Design
chart = {
const svg = d3.create("svg")
.attr("viewBox", [0, 0, width, height]);
svg.append("g")
.attr("fill", "steelblue")
.selectAll("rect")
.data(bins)
.join("rect")
.attr("x", d => x(d.x0) + 1)
.attr("width", d => Math.max(0, x(d.x1) - x(d.x0) - 1))
.attr("y", d => y(d.length))
.attr("height", d => y(0) - y(d.length));
svg.append("g")
.call(xAxis);
svg.append("g")
.call(yAxis);
return svg.node();
}
data = {
const data = await d3.json("https://data.sfgov.org/resource/vw6y-z8j6.json?$limit=5000");
data.forEach(d => {
d.requested_datetime = new Date(d.requested_datetime);
if (d.updated_datetime) d.updated_datetime = new Date(d.updated_datetime);
if (d.closed_date) d.closed_date = new Date(d.closed_date);
})
return Object.assign(data, { x: "", y: "Incidents" });
}
dateTimeExtent = d3.extent(data, d => d.requested_datetime)
// used to bin data by a time interval consistently, here data is being binned in a 2 hour interval
thresholds = d3.timeHour.every(2).range(...dateTimeExtent)
bins = d3.histogram()
.domain(dateTimeExtent)
.thresholds(thresholds)
.value(d => d.requested_datetime)
(data)
x = d3.scaleTime()
.domain(dateTimeExtent)
.range([margin.left, width - margin.right])
y = d3.scaleLinear()
.domain([0, d3.max(bins, d => d.length)]).nice()
.range([height - margin.bottom, margin.top])
xAxis = g => g
.attr("transform", `translate(0,${height - margin.bottom})`)
.call(d3.axisBottom(x)
.tickValues(thresholds) // <-- aligns ticks with bins correctly
.tickSizeOuter(0))
.call(g => g.selectAll(".tick > text")
.attr("transform", "rotate(90) translate(23 -12)")) // <-- rotates axis tick labels to keep them readable
.call(g => g.append("text")
.attr("x", width - margin.right)
.attr("y", -4)
.attr("fill", "currentColor")
.attr("font-weight", "bold")
.attr("text-anchor", "end")
.text(data.x))
yAxis = g => g
.attr("transform", `translate(${margin.left},0)`)
.call(d3.axisLeft(y).ticks(height / 40))
.call(g => g.select(".domain").remove())
.call(g => g.select(".tick:last-of-type text").clone()
.attr("x", 4)
.attr("text-anchor", "start")
.attr("font-weight", "bold")
.text(data.y))
height = 500
margin = ({top: 20, right: 20, bottom: 60, left: 40})
d3 = require("d3@5")
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.
