Visualization toolmaker. Founder @observablehq. Creator @d3. Former @nytgraphics. Pronounced BOSS-tock.
Published
Edited
Feb 17, 2019
1 fork
Importers
1 star
[...samples([0, 1], 100)]
function* samples([min, max], n, k = 30) {
if (!(max > min)) throw new Error("max > min");
let width = max - min;
let radius = width / (n * 1.5);
let R = 3 * radius;
let cellSize = radius * Math.SQRT1_2;
let gridWidth = Math.ceil(width / cellSize);
let grid = new Array(gridWidth);
let queue = [];
let queueSize = 0;
let sampleSize = 0;
function far(x) {
const i = x / cellSize | 0;
const i0 = Math.max(i - 2, 0);
const i1 = Math.min(i + 3, gridWidth);
for (let i = i0; i < i1; ++i) {
const s = grid[i];
if (s) {
const dx = s - x;
if (Math.abs(dx) < radius) return false;
}
}
return true;
}
function sample(x) {
queue.push(x);
grid[x / cellSize | 0] = x;
++sampleSize;
++queueSize;
return x + min;
}
yield sample(Math.random() * width);
sampling: while (queueSize) {
let i = Math.random() * queueSize | 0;
let s = queue[i];
for (let j = 0; j < k; ++j) {
let r = Math.random();
let x = s + (r < 0.5 ? -1 : +1) * (radius + Math.random() * radius);
if (0 <= x && x < width && far(x)) {
yield sample(x);
continue sampling;
}
}
queue[i] = queue[--queueSize];
queue.length = queueSize;
}
}
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