Visualization toolmaker. Founder @observablehq. Creator @d3. Former @nytgraphics. Pronounced BOSS-tock.
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Beta-Distributed Random Values
function randb(alpha, beta) {
const u = randg(alpha);
return u / (u + randg(beta));
}
// Returns a gamma deviate by the method of Marsaglia and Tsang.
function randg(shape) {
let oalph = shape, a1, a2, u, v, x, mat;
if (!shape) shape = 1;
if (shape < 1) shape += 1;
a1 = shape - 1 / 3;
a2 = 1 / Math.sqrt(9 * a1);
do {
do {
x = randn();
v = 1 + a2 * x;
} while (v <= 0);
v = v * v * v;
u = Math.random();
} while (
u > 1 - 0.331 * Math.pow(x, 4) &&
Math.log(u) > 0.5 * x * x + a1 * (1 - v + Math.log(v))
);
if (shape === oalph) return a1 * v; // alpha > 1
do u = Math.random(); while (u === 0); // alpha < 1
return Math.pow(u, 1 / oalph) * a1 * v;
}
// Returns a normal deviate (mu=0, sigma=1).
function randn() {
let u, v, x, y, q;
do {
u = Math.random();
v = 1.7156 * (Math.random() - 0.5);
x = u - 0.449871;
y = Math.abs(v) + 0.386595;
q = x * x + y * (0.19600 * y - 0.25472 * x);
} while (q > 0.27597 && (q > 0.27846 || v * v > -4 * Math.log(u) * u * u));
return v / u;
}
One platform to build and deploy the best data apps
Experiment and prototype by building visualizations in live JavaScript notebooks. Collaborate with your team and decide which concepts to build out.
Use Observable Framework to build data apps locally. Use data loaders to build in any language or library, including Python, SQL, and R.
Seamlessly deploy to Observable. Test before you ship, use automatic deploy-on-commit, and ensure your projects are always up-to-date.