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<!DOCTYPE html> |
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<style> |
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.axis .domain { |
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display: none; |
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} |
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</style> |
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<svg width="960" height="500"></svg> |
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<script src="https://d3js.org/d3.v4.min.js"></script> |
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<script> |
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// Commented version of |
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// https://bl.ocks.org/mbostock/3887051 |
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// Variables |
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var svg = d3.select("svg"), |
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margin = {top: 20, right: 20, bottom: 30, left: 40}, |
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width = +svg.attr("width") - margin.left - margin.right, |
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height = +svg.attr("height") - margin.top - margin.bottom; |
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// SVG G to provide D3 Margin Convention |
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var g = svg.append("g").attr("transform", "translate(" + margin.left + "," + margin.top + ")"); |
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// X0 (horizontal axis) represents the state categories |
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var x0 = d3.scaleBand() |
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.rangeRound([0, width]) |
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.paddingInner(0.1); |
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// X1 (horizontal axis) represents the age group categories |
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var x1 = d3.scaleBand() |
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.padding(0.05); |
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// Y (vertical axis) represents the population in millions |
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var y = d3.scaleLinear() |
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.rangeRound([height, 0]); |
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// Z represents the color scheme to be used for the various age groups |
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var z = d3.scaleOrdinal() |
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.range(["#98abc5", "#8a89a6", "#7b6888", "#6b486b", "#a05d56", "#d0743c", "#ff8c00"]); |
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// Define variable to give us access to AJAX callback function data |
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var outsideData; |
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// CSV AJAX call to ingest data |
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// data file requested: data.csv |
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// function to process data: function(d, i, columns) {...} |
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// function to be used on call back: function(error, data) {...} |
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d3.csv("data.csv", function(d, i, columns) { |
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for (var i = 1, n = columns.length; i < n; ++i) d[columns[i]] = +d[columns[i]]; |
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return d; |
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}, function(error, data) { |
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if (error) throw error; |
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// assign internal data variable to outsideData variable so we can see data |
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// once the AJAX callback function has been run. |
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outsideData = data; |
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// Get the keys by taking a slice off of the column headings |
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// (means remove the element 0, and return array from index 1 to end) |
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// Returns array containing: |
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// "Under 5 Years", "5 to 13 Years", "14 to 17 Years", |
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// "18 to 24 Years", "25 to 44 Years", "45 to 64 Years", |
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// "65 Years and Over" |
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var keys = data.columns.slice(1); |
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// Finish defining the X0 (horizontal) state categories scale |
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x0.domain(data.map(function(d) { return d.State; })); |
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// Finish defining the X1 (horizontal) state categories scale |
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// Use the bandwidth of each state to set to range of x1 |
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// The rounding gives a nice visual effect |
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x1.domain(keys).rangeRound([0, x0.bandwidth()]); |
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// Finish defining the Y axis |
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// Note the following: |
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// - d3.max(data...) |
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// - d3.max(keys, ...) |
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// => Think of it as a nested for loop |
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// => loop through each state and then within each state loop through each age group |
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y.domain([0, d3.max(data, function(d) { return d3.max(keys, function(key) { return d[key]; }); })]).nice(); |
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// Double Data Join |
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// First data join will give us the states |
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// - Each g receives state and age group object |
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// Second data join will give us the rectangles |
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// - Within the data join, we build a new object from scratch |
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// - These will be the specific age groups |
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// - Each rectangle receives the specific age group per state |
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// - By the end of this, we have a small bar chart for each agre group. |
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g.append("g") |
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.selectAll("g") |
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.data(data) |
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.enter().append("g") |
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.attr("transform", function(d) { return "translate(" + x0(d.State) + ",0)"; }) |
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.selectAll("rect") |
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.data(function(d) { return keys.map(function(key) { return {key: key, value: d[key]}; }); }) |
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.enter().append("rect") |
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.attr("x", function(d) { return x1(d.key); }) |
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.attr("y", function(d) { return y(d.value); }) |
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.attr("width", x1.bandwidth()) |
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.attr("height", function(d) { return height - y(d.value); }) |
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.attr("fill", function(d) { return z(d.key); }); |
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// Create the X Axis |
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g.append("g") |
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.attr("class", "axis") |
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.attr("transform", "translate(0," + height + ")") |
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.call(d3.axisBottom(x0)); |
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// Create the Y Axis |
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g.append("g") |
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.attr("class", "axis") |
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.call(d3.axisLeft(y).ticks(null, "s")) |
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.append("text") |
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.attr("x", 2) |
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.attr("y", y(y.ticks().pop()) + 0.5) |
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.attr("dy", "0.32em") |
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.attr("fill", "#000") |
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.attr("font-weight", "bold") |
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.attr("text-anchor", "start") |
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.text("Population"); |
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// Create the legend g's |
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// Note the data join |
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// Note the transform translate based on the selection element index |
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var legend = g.append("g") |
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.attr("font-family", "sans-serif") |
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.attr("font-size", 10) |
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.attr("text-anchor", "end") |
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.selectAll("g") |
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.data(keys.slice().reverse()) |
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.enter().append("g") |
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.attr("transform", function(d, i) { return "translate(0," + i * 20 + ")"; }); |
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// Create rectangles for each legend g |
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// Pass rect index to Z color ordinal scale |
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legend.append("rect") |
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.attr("x", width - 19) |
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.attr("width", 19) |
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.attr("height", 19) |
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.attr("fill", z); |
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// Create text for each legend g |
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// Use the data that it inherts to create the SVG text |
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legend.append("text") |
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.attr("x", width - 24) |
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.attr("y", 9.5) |
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.attr("dy", "0.32em") |
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.text(function(d) { return d; }); |
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}); |
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</script> |
