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<!DOCTYPE html> |
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<html> |
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<head> |
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<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/> |
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<title>Canvas Parallel Coordinates</title> |
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<style type="text/css"> |
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svg { |
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font: 10px sans-serif; |
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} |
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canvas, svg { |
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position: absolute; |
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top: 0; |
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left: 0; |
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} |
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#chart { |
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position: relative; |
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} |
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.brush .extent { |
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fill-opacity: .3; |
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stroke: #fff; |
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shape-rendering: crispEdges; |
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} |
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.axis line, .axis path { |
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fill: none; |
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stroke: #000; |
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shape-rendering: crispEdges; |
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} |
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.axis text { |
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text-shadow: 0 1px 0 #fff; |
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} |
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</style> |
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</head> |
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<body> |
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<div id="chart"> |
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<canvas id="background"></canvas> |
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<canvas id="foreground"></canvas> |
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<svg></svg> |
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</div> |
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<script type="text/javascript" src="https://d3js.org/d3.v2.js"></script> |
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<script type="text/javascript"> |
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var m = [30, 10, 10, 10], |
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w = 960 - m[1] - m[3], |
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h = 500 - m[0] - m[2]; |
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var x = d3.scale.ordinal().rangePoints([0, w], 1), |
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y = {}; |
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var line = d3.svg.line(), |
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axis = d3.svg.axis().orient("left"), |
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background, |
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foreground; |
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d3.selectAll("canvas") |
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.attr("width", w + m[1] + m[3]) |
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.attr("height", h + m[0] + m[2]) |
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.style("padding", m.join("px ") + "px"); |
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foreground = document.getElementById('foreground').getContext('2d'); |
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background = document.getElementById('background').getContext('2d'); |
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foreground.strokeStyle = "rgba(0,100,160,0.24)"; |
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background.strokeStyle = "rgba(0,0,0,0.02)"; |
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var svg = d3.select("svg") |
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.attr("width", w + m[1] + m[3]) |
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.attr("height", h + m[0] + m[2]) |
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.append("svg:g") |
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.attr("transform", "translate(" + m[3] + "," + m[0] + ")"); |
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d3.csv("cars.csv", function(cars) { |
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// Extract the list of dimensions and create a scale for each. |
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x.domain(dimensions = d3.keys(cars[0]).filter(function(d) { |
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return d != "name" && (y[d] = d3.scale.linear() |
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.domain(d3.extent(cars, function(p) { return +p[d]; })) |
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.range([h, 0])); |
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})); |
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// Render full foreground and background |
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cars.map(function(d) { |
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path(d, background); |
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path(d, foreground); |
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}); |
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// Add a group element for each dimension. |
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var g = svg.selectAll(".dimension") |
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.data(dimensions) |
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.enter().append("svg:g") |
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.attr("class", "dimension") |
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.attr("transform", function(d) { return "translate(" + x(d) + ")"; }); |
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// Add an axis and title. |
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g.append("svg:g") |
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.attr("class", "axis") |
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.each(function(d) { d3.select(this).call(axis.scale(y[d])); }) |
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.append("svg:text") |
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.attr("text-anchor", "middle") |
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.attr("y", -9) |
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.text(String); |
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// Add and store a brush for each axis. |
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g.append("svg:g") |
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.attr("class", "brush") |
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.each(function(d) { d3.select(this).call(y[d].brush = d3.svg.brush().y(y[d]).on("brush", brush)); }) |
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.selectAll("rect") |
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.attr("x", -8) |
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.attr("width", 16); |
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// Handles a brush event, toggling the display of foreground lines. |
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function brush() { |
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var actives = dimensions.filter(function(p) { return !y[p].brush.empty(); }), |
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extents = actives.map(function(p) { return y[p].brush.extent(); }); |
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// Get lines within extents |
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var selected = []; |
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cars.map(function(d) { |
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return actives.every(function(p, i) { |
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return extents[i][0] <= d[p] && d[p] <= extents[i][1]; |
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}) ? selected.push(d) : null; |
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}); |
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// Render selected lines |
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foreground.clearRect(0,0,w+1,h+1); |
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selected.map(function(d) { |
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path(d, foreground); |
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}); |
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} |
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}); |
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function path(d, ctx) { |
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ctx.beginPath(); |
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dimensions.map(function(p,i) { |
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if (i == 0) { |
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ctx.moveTo(x(p),y[p](d[p])); |
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} else { |
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ctx.lineTo(x(p),y[p](d[p])); |
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} |
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}); |
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ctx.stroke(); |
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}; |
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</script> |
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</body> |
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</html> |