This stacked bar chart is constructed from a CSV file storing the populations of different states by age group. The chart employs conventional margins and a number of D3 features:
xxxxxxxxxx<style>.axis .domain { display: none;}</style><svg width="960" height="500"></svg><script src="https://d3js.org/d3.v4.min.js"></script><script>// Commented version of// https://bl.ocks.org/mbostock/3886208// Variablesvar svg = d3.select("svg"), margin = {top: 20, right: 20, bottom: 30, left: 40}, width = +svg.attr("width") - margin.left - margin.right, height = +svg.attr("height") - margin.top - margin.bottom;// SVG G to provide D3 Margin Conventionvar g = svg.append("g").attr("transform", "translate(" + margin.left + "," + margin.top + ")");// X (horizontal axis) represents the state categories// - paddingInner provides spacing between bars// - align specifies unused space in the range and how to distribute itvar x = d3.scaleBand() .rangeRound([0, width]) .paddingInner(0.05) .align(0.1);// Y (vertical axis) represents the population in millionsvar y = d3.scaleLinear() .rangeRound([height, 0]);// Z represents the color scheme to be used for the various age groupsvar z = d3.scaleOrdinal() .range(["#98abc5", "#8a89a6", "#7b6888", "#6b486b", "#a05d56", "#d0743c", "#ff8c00"]);// Define variable to give us access to AJAX callback function datavar outsideData;// CSV AJAX call to ingest data// data file requested: data.csv// function to process data: function(d, i, columns) {...}// function to be used on call back: function(error, data) {...}d3.csv("data.csv", function(d, i, columns) { for (i = 1, t = 0; i < columns.length; ++i) t += d[columns[i]] = +d[columns[i]]; d.total = t; return d;}, function(error, data) { if (error) throw error; // assign internal data variable to outsideData variable so we can see data // once the AJAX callback function has been run. outsideData = data; // Get the keys by taking a slice off of the column headings // (means remove the element 0, and return array from index 1 to end) // Returns array containing: // "Under 5 Years", "5 to 13 Years", "14 to 17 Years", // "18 to 24 Years", "25 to 44 Years", "45 to 64 Years", // "65 Years and Over" var keys = data.columns.slice(1); // JavaScript Array Sort function sorts by total // - total coming from the d3.scv middle function that added all categories together per state data.sort(function(a, b) { return b.total - a.total; }); // X axis domain is all the states x.domain(data.map(function(d) { return d.State; })); // Y axis domain is the additive total of each state y.domain([0, d3.max(data, function(d) { return d.total; })]).nice(); // Z color scale needs colors defined so use the keys z.domain(keys); // Double Data Join // First data join will give us the states // - Note that the d3 stack generator is being used // - We have to define what the keys are for the stack // - We have to pass in the data to the generator function // - What the stack does is create layers per key // - For each state it gives us a layer per category // - That's why all the states receive the same rectangle fill color // - So you end up with <g fill="#98abc5"> // - You want to think of each <g> element as a layer // Second data join constructs the rectangles in each G // - So it takes the d3.stack().keys(keys)(data) generated data for each g // - And creates a bunch of rectangles within the layer // - note the d.data.State passed to the ordinal scale function g.append("g") .selectAll("g") .data(d3.stack().keys(keys)(data)) .enter().append("g") .attr("fill", function(d) { return z(d.key); }) .selectAll("rect") .data(function(d) { return d; }) .enter().append("rect") .attr("x", function(d) { return x(d.data.State); }) .attr("y", function(d) { return y(d[1]); }) .attr("height", function(d) { return y(d[0]) - y(d[1]); }) .attr("width", x.bandwidth()); // Create the X Axis g.append("g") .attr("class", "axis") .attr("transform", "translate(0," + height + ")") .call(d3.axisBottom(x)); // Create the Y Axis g.append("g") .attr("class", "axis") .call(d3.axisLeft(y).ticks(null, "s")) .append("text") .attr("x", 2) .attr("y", y(y.ticks().pop()) + 0.5) .attr("dy", "0.32em") .attr("fill", "#000") .attr("font-weight", "bold") .attr("text-anchor", "start") .text("Population"); // Create the legend g's // Note the data join // Note the transform translate based on the selection element index var legend = g.append("g") .attr("font-family", "sans-serif") .attr("font-size", 10) .attr("text-anchor", "end") .selectAll("g") .data(keys.slice().reverse()) .enter().append("g") .attr("transform", function(d, i) { return "translate(0," + i * 20 + ")"; }); // Create rectangles for each legend g // Pass rect index to Z color ordinal scale legend.append("rect") .attr("x", width - 19) .attr("width", 19) .attr("height", 19) .attr("fill", z); // Create text for each legend g // Use the data that it inherts to create the SVG text legend.append("text") .attr("x", width - 24) .attr("y", 9.5) .attr("dy", "0.32em") .text(function(d) { return d; });});</script> https://d3js.org/d3.v4.min.js