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<html> |
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<head> |
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<style> |
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/* Any styling on the SVG won't transfer to the Canvas */ |
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/* Styling must be done inline */ |
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</style> |
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</head> |
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<body> |
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<script src="https://d3js.org/d3.v4.min.js"></script> |
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<script> |
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var margin = { top: 20, right: 20, bottom: 30, left: 40 }, |
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width = 960 - margin.left - margin.right, |
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height = 500 - margin.top - margin.bottom; |
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var x = d3.scaleBand() |
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.rangeRound([0, width]) |
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.padding(0.1); |
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var y = d3.scaleLinear() |
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.rangeRound([height, 0]); |
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var svg = d3.select("body").append("svg") |
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.attr("xmlns", "http://www.w3.org/2000/svg") |
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.attr("width", width + margin.left + margin.right) |
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.attr("height", height + margin.top + margin.bottom); |
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var g = svg.append("g") |
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.attr("transform", "translate(" + margin.left + "," + margin.top + ")"); |
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var canvas = d3.select("body").append("canvas") |
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.attr("width", width + margin.left + margin.right) |
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.attr("height", height + margin.top + margin.bottom); |
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var context = canvas.node().getContext("2d"); |
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d3.tsv("data.tsv", processRow, function(error, data) { |
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if (error) throw error; |
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// Update scales |
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x.domain(data.map(function(d) { return d.letter; })); |
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y.domain([0, d3.max(data, function(d) { return d.frequency; })]); |
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// Draw axes |
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g.append("g") |
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.attr("class", "axis axis--x") |
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.attr("transform", "translate(0," + height + ")") |
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.call(d3.axisBottom(x)) |
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.select("path") |
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.style("stroke", "none"); |
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g.append("g") |
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.attr("class", "axis axis--y") |
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.call(d3.axisLeft(y).tickFormat(d3.format(".0%"))) |
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.append("text") |
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.attr("transform", "rotate(-90)") |
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.attr("dx", "-1em") |
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.attr("dy", "1.66em") |
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.style("fill", "#000") |
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.text("Frequency"); |
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// Draw bars |
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g.append("g") |
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.attr("class", "bars") |
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.selectAll(".bar").data(data) |
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.enter().append("rect") |
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.attr("class", "bar") |
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.attr("x", function(d) { return x(d.letter); }) |
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.attr("y", function(d) { return y(d.frequency); }) |
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.attr("width", x.bandwidth()) |
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.attr("height", function(d) { return height - y(d.frequency); }) |
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.style("fill", "steelblue"); |
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// Convert SVG to Canvas |
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// see: https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Drawing_DOM_objects_into_a_canvas |
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var DOMURL = window.URL || window.webkitURL || window; |
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var svgString = domNodeToString(svg.node()); |
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var image = new Image(); |
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var svgBlob = new Blob([svgString], { type: "image/svg+xml;charset=utf-8" }); |
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var url = DOMURL.createObjectURL(svgBlob); |
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image.onload = function() { |
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context.drawImage(image, 0, 0); |
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DOMURL.revokeObjectURL(url); |
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} |
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image.src = url; |
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}); |
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function processRow(d) { |
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d.frequency = +d.frequency; |
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return d; |
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} |
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// Get the string representation of a DOM node (removes the node) |
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function domNodeToString(domNode) { |
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var element = document.createElement("div"); |
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element.appendChild(domNode); |
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return element.innerHTML; |
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} |
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</script> |
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</body> |
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</html> |