Published
Edited
Jun 24, 2020
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md`# Making bar chart`
md`Loading D3.js package into the Observable environment:`
d3 = require("d3@5")
md`Defining color, size, and margin attributes of the bar chart:`
color = "steelblue"
height = 500
margin = ({top: 30, right: 0, bottom: 30, left: 40})
md`Loading data:`
data = d3.csvParse(await FileAttachment("data-sc.csv").text(), d3.autoType)
md`Defining scales and axes:`
x = d3.scaleBand()
.domain(d3.range(data.length))
.range([margin.left, 3.0*width - margin.right])
.padding(0.1)
y = d3.scaleLinear()
.domain([0, d3.max(data, d => d.Cases)]).nice()
.range([height - margin.bottom, margin.top])
xAxis = g => g
.attr("transform", `translate(0,${height - margin.bottom})`)
.call(d3.axisBottom(x).tickFormat(i => data[i].County).tickSizeOuter(0))
yAxis = g => g
.attr("transform", `translate(${margin.left},0)`)
.call(d3.axisLeft(y).ticks(null, data.format))
.call(g => g.select(".domain").remove())
.call(g => g.append("text")
.attr("x", -margin.left)
.attr("y", 10)
.attr("fill", "currentColor")
.attr("text-anchor", "start")
.text(data.Cases))
md`Creating bar chart:`
chart = {
const svg = d3.create("svg")
.attr("viewBox", [0, 0, width, height]);
svg.append("g")
.attr("fill", color)
.selectAll("rect")
.data(data)
.join("rect")
.attr("x", (d, i) => x(i))
.attr("y", d => y(d.Cases))
.attr("height", d => y(0) - y(d.Cases))
.attr("width", x.bandwidth());
svg.append("g")
.call(xAxis);
svg.append("g")
.call(yAxis);
return svg.node();
}
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.
