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rjurney/.block

Created June 18, 2017 03:17
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Simple Box Plot Example in d3.js v4.0
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.block
license: mit
Raw
index.html
<!DOCTYPE html>
<head>
<meta charset="utf-8">
<script src="https://d3js.org/d3.v4.min.js"></script>
<style>
body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
</style>
</head>
<body>
<script>
var width = 900;
var height = 400;
var barWidth = 30;
var margin = {top: 20, right: 10, bottom: 20, left: 10};
var width = width - margin.left - margin.right,
height = height - margin.top - margin.bottom;
var totalWidth = width + margin.left + margin.right;
var totalheight = height + margin.top + margin.bottom;
// Generate five 100 count, normal distributions with random means
var groupCounts = {};
var globalCounts = [];
var meanGenerator = d3.randomUniform(10);
for(i=0; i<7; i++) {
var randomMean = meanGenerator();
var generator = d3.randomNormal(randomMean);
var key = i.toString();
groupCounts[key] = [];
for(j=0; j<100; j++) {
var entry = generator();
groupCounts[key].push(entry);
globalCounts.push(entry);
}
}
// Sort group counts so quantile methods work
for(var key in groupCounts) {
var groupCount = groupCounts[key];
groupCounts[key] = groupCount.sort(sortNumber);
}
// Setup a color scale for filling each box
var colorScale = d3.scaleOrdinal(d3.schemeCategory20)
.domain(Object.keys(groupCounts));
// Prepare the data for the box plots
var boxPlotData = [];
for (var [key, groupCount] of Object.entries(groupCounts)) {
var record = {};
var localMin = d3.min(groupCount);
var localMax = d3.max(groupCount);
record["key"] = key;
record["counts"] = groupCount;
record["quartile"] = boxQuartiles(groupCount);
record["whiskers"] = [localMin, localMax];
record["color"] = colorScale(key);
boxPlotData.push(record);
}
// Compute an ordinal xScale for the keys in boxPlotData
var xScale = d3.scalePoint()
.domain(Object.keys(groupCounts))
.rangeRound([0, width])
.padding([0.5]);
// Compute a global y scale based on the global counts
var min = d3.min(globalCounts);
var max = d3.max(globalCounts);
var yScale = d3.scaleLinear()
.domain([min, max])
.range([0, height]);
// Setup the svg and group we will draw the box plot in
var svg = d3.select("body").append("svg")
.attr("width", totalWidth)
.attr("height", totalheight)
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
// Move the left axis over 25 pixels, and the top axis over 35 pixels
var axisG = svg.append("g").attr("transform", "translate(25,0)");
var axisTopG = svg.append("g").attr("transform", "translate(35,0)");
// Setup the group the box plot elements will render in
var g = svg.append("g")
.attr("transform", "translate(20,5)");
// Draw the box plot vertical lines
var verticalLines = g.selectAll(".verticalLines")
.data(boxPlotData)
.enter()
.append("line")
.attr("x1", function(datum) {
return xScale(datum.key) + barWidth/2;
}
)
.attr("y1", function(datum) {
var whisker = datum.whiskers[0];
return yScale(whisker);
}
)
.attr("x2", function(datum) {
return xScale(datum.key) + barWidth/2;
}
)
.attr("y2", function(datum) {
var whisker = datum.whiskers[1];
return yScale(whisker);
}
)
.attr("stroke", "#000")
.attr("stroke-width", 1)
.attr("fill", "none");
// Draw the boxes of the box plot, filled in white and on top of vertical lines
var rects = g.selectAll("rect")
.data(boxPlotData)
.enter()
.append("rect")
.attr("width", barWidth)
.attr("height", function(datum) {
var quartiles = datum.quartile;
var height = yScale(quartiles[2]) - yScale(quartiles[0]);
return height;
}
)
.attr("x", function(datum) {
return xScale(datum.key);
}
)
.attr("y", function(datum) {
return yScale(datum.quartile[0]);
}
)
.attr("fill", function(datum) {
return datum.color;
}
)
.attr("stroke", "#000")
.attr("stroke-width", 1);
// Now render all the horizontal lines at once - the whiskers and the median
var horizontalLineConfigs = [
// Top whisker
{
x1: function(datum) { return xScale(datum.key) },
y1: function(datum) { return yScale(datum.whiskers[0]) },
x2: function(datum) { return xScale(datum.key) + barWidth },
y2: function(datum) { return yScale(datum.whiskers[0]) }
},
// Median line
{
x1: function(datum) { return xScale(datum.key) },
y1: function(datum) { return yScale(datum.quartile[1]) },
x2: function(datum) { return xScale(datum.key) + barWidth },
y2: function(datum) { return yScale(datum.quartile[1]) }
},
// Bottom whisker
{
x1: function(datum) { return xScale(datum.key) },
y1: function(datum) { return yScale(datum.whiskers[1]) },
x2: function(datum) { return xScale(datum.key) + barWidth },
y2: function(datum) { return yScale(datum.whiskers[1]) }
}
];
for(var i=0; i < horizontalLineConfigs.length; i++) {
var lineConfig = horizontalLineConfigs[i];
// Draw the whiskers at the min for this series
var horizontalLine = g.selectAll(".whiskers")
.data(boxPlotData)
.enter()
.append("line")
.attr("x1", lineConfig.x1)
.attr("y1", lineConfig.y1)
.attr("x2", lineConfig.x2)
.attr("y2", lineConfig.y2)
.attr("stroke", "#000")
.attr("stroke-width", 1)
.attr("fill", "none");
}
// Setup a scale on the left
var axisLeft = d3.axisLeft(yScale);
axisG.append("g")
.call(axisLeft);
// Setup a series axis on the top
var axisTop = d3.axisTop(xScale);
axisTopG.append("g")
.call(axisTop);
function boxQuartiles(d) {
return [
d3.quantile(d, .25),
d3.quantile(d, .5),
d3.quantile(d, .75)
];
}
// Perform a numeric sort on an array
function sortNumber(a,b) {
return a - b;
}
</script>
</body>
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