Shuffle, pick and weight choices

Use the right draw

below excludes its upper bound, int includes both ends, and float excludes the upper end. pick chooses one item. shuffled copies a list; shuffle changes its supplied array in place.

import { int, mulberry32, sample, shuffled, weightedPick } from "@johnmorrisdotca/tane";

const random = mulberry32(42);
const names = ["Aki", "Ben", "Cy", "Dev"];
console.log(int(random, 1, 6));
console.log(shuffled(random, names));
console.log(sample(random, names, 2));
console.log(weightedPick(random, ["small", "large"], [3, 1]));
console.log(names);

4
[ 'Aki', 'Dev', 'Cy', 'Ben' ]
[ 'Aki', 'Cy' ]
small
[ 'Aki', 'Ben', 'Cy', 'Dev' ]

Sample without replacement

sample chooses distinct list positions and clamps a request larger than the list to its length. Equal values can still appear if the input itself repeats them. distinctBelow uses rejection draws, so its consumed count can vary; prefer sample for new code and retain distinctBelow when an existing seed’s behavior depends on it.

Match weights to items

Pass one nonnegative weight per item to weightedPick. weightedIndex returns 0 when the weights total nothing. Use the native functions; a change in how many source draws your recipe consumes changes the later stream. The specification records those compatibility rules.