baskin-lib/dist/lib/randUtil.js

baskin robbins 31 web game library

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.randomArray = exports.getRandomIntAsVec = exports.randomSampleOne = exports.getRandomInt = exports.getRandom = void 0;
const linarg_1 = require("./linarg");
/**
 *
 * @param min Min value.
 * @param max Max value. Excluded.
 * @returns Random float in interval [`min`, `max`)
 */
function getRandom(min, max) {
    return Math.random() * (max - min) + min;
}
exports.getRandom = getRandom;
/**
 *
 * @param min Min value.
 * @param max Max value. Excluded.
 * @returns Random integer in interval [`min`, `max`).
 */
function getRandomInt(min, max) {
    return Math.floor(getRandom(Math.ceil(min), Math.floor(max)));
}
exports.getRandomInt = getRandomInt;
/**
 *
 * @param vec Input vector
 * @returns Random sample from the vector
 */
function randomSampleOne(vec) {
    const pickedIdx = getRandomInt(0, vec.length);
    return vec[pickedIdx];
}
exports.randomSampleOne = randomSampleOne;
/**
 *
 * @param chooseProb normalized vector of choose probability
 * @returns random sample of index rate proportional to `vec`
 */
function getRandomIntAsVec(chooseProb) {
    const cumsum = (0, linarg_1.vecCumSum)(chooseProb);
    const rand = Math.random();
    var i = 0;
    var lower = 0;
    var upper = cumsum[i];
    while (i < cumsum.length) {
        if (rand >= lower && rand < upper) {
            return i;
        }
        i++;
        lower = cumsum[i - 1];
        upper = cumsum[i];
    }
    throw new Error("invalid parameters");
}
exports.getRandomIntAsVec = getRandomIntAsVec;
/**
 *
 * @param len length of the array
 * @returns `len` of array filled with random number
 */
function randomArray(len) {
    return Array.from(Array(len)).map((_) => Math.random());
}
exports.randomArray = randomArray;