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@jwilber
Created May 4, 2019 03:01
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basic density plot
license: mit
<!DOCTYPE html>
<meta charset="utf-8">
<!-- Load d3.js -->
<script src="https://d3js.org/d3.v4.js"></script>
<!-- Create a div where the graph will take place -->
<div id="my_dataviz"></div>
<script>
// set the dimensions and margins of the graph
var margin = {top: 30, right: 30, bottom: 30, left: 50},
width = 460 - margin.left - margin.right,
height = 400 - margin.top - margin.bottom;
// append the svg object to the body of the page
var svg = d3.select("#my_dataviz")
.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 + ")");
// get the data
d3.csv("https://raw.githubusercontent.com/holtzy/data_to_viz/master/Example_dataset/1_OneNum.csv", function(data) {
// add the x Axis
var x = d3.scaleLinear()
.domain([0, 1000])
.range([0, width]);
svg.append("g")
.attr("transform", "translate(0," + height + ")")
.call(d3.axisBottom(x));
// add the y Axis
var y = d3.scaleLinear()
.range([height, 0])
.domain([0, 0.01]);
svg.append("g")
.call(d3.axisLeft(y));
// Compute kernel density estimation
var kde = kernelDensityEstimator(kernelEpanechnikov(7), x.ticks(40))
var density = kde( data.map(function(d){ return d.price; }) )
// Plot the area
svg.append("path")
.attr("class", "mypath")
.datum(density)
.attr("fill", "#69b3a2")
.attr("opacity", ".8")
.attr("stroke", "#000")
.attr("stroke-width", 1)
.attr("stroke-linejoin", "round")
.attr("d", d3.line()
.curve(d3.curveBasis)
.x(function(d) { return x(d[0]); })
.y(function(d) { return y(d[1]); })
);
});
// Function to compute density
function kernelDensityEstimator(kernel, X) {
return function(V) {
return X.map(function(x) {
return [x, d3.mean(V, function(v) { return kernel(x - v); })];
});
};
}
function kernelEpanechnikov(k) {
return function(v) {
return Math.abs(v /= k) <= 1 ? 0.75 * (1 - v * v) / k : 0;
};
}
</script>
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