Ternary binning / Fil

Fil

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Edited

Sep 15, 2023

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{

const svg = d3.create("svg").attr("viewBox", [0, 0, width, height]);

// triangles

const color = d3.scaleSequentialSqrt([0, 40], d3.interpolateBlues);

svg

.append("g")

.selectAll()

.data(bins)

.join("path")

.attr("d", d => `M${d.polygon.map(e => [e.x, e.y]).join("L")}Z`)

.attr("fill", d => color(d.values.length));

// lines

svg

.append("g")

.selectAll()

.data(

[]

.concat(d3.range(0, 1, 1 / ticks).map(x => [[x, 0], [x, 1 - x]]))

.concat(d3.range(0, 1, 1 / ticks).map(x => [[0, x], [1 - x, x]]))

.concat(d3.range(0, 1, 1 / ticks).map(x => [[1 - x, 0], [0, 1 - x]]))

)

.join("path")

.attr(

"d",

d =>

`M${d

.map(transform)

.map(e => [e.x, e.y])

.join("L")}Z`

)

.attr("fill", "none")

.attr("stroke", "black")

.attr("stroke-width", .125);

// contour

svg

.append("g")

.append("path")

.attr(

"d",

d =>

`M${[[0, 0], [0, 1], [1, 0]]

.map(transform)

.map(e => [e.x, e.y])

.join("L")}Z`

)

.attr("fill", "none")

.attr("stroke", "black");

// data points

svg

.append("g")

.selectAll()

.data(data)

.join("circle")

.attr("r", 1.5)

.attr("transform", d => {

const e = transform([+d.agriculture / 100, +d.industry / 100]);

return `translate(${[e.x, e.y]})`;

});

// numbers

svg

.append("g")

.style("text-anchor", "middle")

.style("font-size", "13px")

.selectAll()

.data(bins)

.join("text")

.attr("transform", d => `translate(${[d.x, d.y]})`)

.text(d => d.values.length)

.attr("dy", "0.35em")

.call(g => g.clone(true))

.attr("stroke", "white")

.attr("stroke-width", 3);

// legend

svg

.append("g")

.style("text-anchor", "middle")

.style("font-size", "13px")

.selectAll()

.data([

{ label: "Agriculture", ...transform([1, 0]) },

{ label: "Industry", ...transform([0, 1]) },

{ label: "Services", ...transform([0, 0]) }

])

.join("text")

.attr("transform", d => `translate(${[d.x, d.y]})`)

.text(d => d.label)

.attr("dy", "0.35em")

.call(g => g.clone(true))

.attr("stroke", "white")

.attr("stroke-width", 3);

return svg.node();

}

// 2D affine transform from (a,b) to (x, y).

// The default transform sends the unit domain to [[0, 0], [.5, sqrt(3)/2], [1, 0]]

transform = ([a, b]) => ({

x: 40 + 600 * (a + shear * b),

y: height - 13 - (600 * b * Math.sqrt(3)) / 2

})

ternary = ternarybin()

.coords(d => +d.agriculture, d => +d.industry, d => +d.service)

.ticks(ticks)

.transform(transform)

// from https://observablehq.com/@toja/d3-ternary-plot

data = d3.csv(

"https://gist.githubusercontent.com/toja/811f0ddc765c59c26de544fd0e0ba46f/raw/eef11e930f6c05700faca47711b173f795a84181/sectors.csv"

)

bins = ternary(data)

ternarybin = {

function bin() {

let coords = [d => d[0], d => d[1], d => d[2]];

let normalize = true;

let ticks = 10;

let transform = ([a, b]) => ({x: a + .5 * b, y: Math.sqrt(3) / 2 * b });

function gather(values) {

let i = -1;

const triangles = new d3.InternMap(undefined, JSON.stringify);

for (const v of values) {

const d = [

+coords[0](v, ++i, values),

+coords[1](v, ++i, values),

+coords[2](v, ++i, values)

];

if (normalize) {

const s = d3.sum(d);

d[0] = clamp(d[0] / s, 1e-12, 1-1e-12);

d[1] = clamp(d[1] / s, 1e-12, 1-1e-12);

d[2] = clamp(d[2] / s, 1e-12, 1-1e-12);

}

const a = Math.floor(d[0] * ticks);

const b = Math.floor(d[1] * ticks);

const o = (ticks + 1 + a + b + Math.floor(d[2] * ticks)) % 2;

const c = [ a, b, o ];

if (!triangles.has(c)) triangles.set(c, {

...transform([(a + (1 + o) / 3) / ticks, (b + (1 + o) / 3) / ticks]),

a, b, o,

polygon: o ? [

transform([(a + 1) / ticks, b / ticks]),

transform([a / ticks, (b + 1) / ticks]),

transform([(a + 1) / ticks, (b + 1) / ticks])

] : [

transform([a / ticks, b / ticks]),

transform([a / ticks, (b + 1) / ticks]),

transform([(a + 1) / ticks, b / ticks])

values: []

});

triangles.get(c).values.push(v);

}

return Array.from(triangles.values());

}

gather.coords = (x, y, z) =>

x === undefined ? coords : ((coords = [x, y, z]), gather);

gather.ticks = _ => _ === undefined ? ticks : ((ticks = +_), gather);

gather.transform = _ => _ === undefined ? transform : ((transform = _), gather);

return gather;

}

return bin;

}

function clamp(x, min, max) {

return x < min ? min : x > max ? max : x;

}

height = 550

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