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Last active February 6, 2018 22:11
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Simple Box Plot in d3 v4
Raw
.block
license: apache-2.0
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>
// set the dimensions and margins of the graph
var margin = {top: 20, right: 20, bottom: 30, left: 50},
width = 960 - margin.left - margin.right,
height = 500 - margin.top - margin.bottom;
var barWidth = 30;
// Generate five 100 count, normal distributions with random means
var groupCounts = {};
var globalCounts = [];
var meanGenerator = d3.randomUniform(10);
for(i=0; i <= 5; 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.schemeCategory10)
.domain(Object.keys(groupCounts));
// Prepare the data for the box plots
var boxPlotData = [];
for (var [key, groupCount] of Object.entries(groupCounts)) {
var localMin = d3.min(groupCount);
var localMax = d3.max(groupCount);
var obj = {};
obj["key"] = key;
obj["counts"] = groupCount;
obj["quartile"] = boxQuartiles(groupCount);
obj["whiskers"] = [localMin, localMax];
obj["color"] = colorScale(key);
boxPlotData.push(obj);
}
// 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([height, 0]);
// append the svg obgect to the body of the page
// appends a 'group' element to 'svg'
// moves the 'group' element to the top left margin
var svg = d3.select("body").append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform",
"translate(" + margin.left + "," + margin.top + ")");
// append a group for the box plot elements
var g = svg.append("g");
// Draw the box plot vertical lines
var verticalLines = g.selectAll(".verticalLines")
.data(boxPlotData)
.enter()
.append("line")
.attr("x1", function(datum) { return xScale(datum.key); })
.attr("y1", function(datum) { return yScale(datum.whiskers[0]); })
.attr("x2", function(datum) { return xScale(datum.key); })
.attr("y2", function(datum) { return yScale(datum.whiskers[1]); })
.attr("stroke", "#000")
.attr("stroke-width", 1)
.attr("fill", "none");
// Draw the boxes of the box plot, filled 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[0]) - yScale(quartiles[2]);
return height;
})
.attr("x", function(datum) { return xScale(datum.key) - (barWidth/2); })
.attr("y", function(datum) { return yScale(datum.quartile[2]); })
.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) - barWidth/2 },
y1: function(datum) { return yScale(datum.whiskers[0]) },
x2: function(datum) { return xScale(datum.key) + barWidth/2 },
y2: function(datum) { return yScale(datum.whiskers[0]) }
},
// Median line
{
x1: function(datum) { return xScale(datum.key) - barWidth/2 },
y1: function(datum) { return yScale(datum.quartile[1]) },
x2: function(datum) { return xScale(datum.key) + barWidth/2 },
y2: function(datum) { return yScale(datum.quartile[1]) }
},
// Bottom whisker
{
x1: function(datum) { return xScale(datum.key) - barWidth/2 },
y1: function(datum) { return yScale(datum.whiskers[1]) },
x2: function(datum) { return xScale(datum.key) + barWidth/2 },
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");
}
// Move the left axis over 25 pixels, and the top axis over 35 pixels
//var axisY = svg.append("g").attr("transform", "translate(25,0)");
//var axisX = svg.append("g").attr("transform", "translate(35,0)");
//x-axis
svg.append("g")
.attr("transform", "translate(0," + height + ")")
.call(d3.axisBottom(xScale));
// Add the Y Axis
svg.append("g")
.call(d3.axisLeft(yScale));
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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