Weighted-Randomly-Select

This package lets you easily perform weighted random selection. Provide an array
of objects with chance and result properties, and a random result will be
selected according to the provided chance values.

thanks to author Rifdhan.

https://github.com/Rifdhan/weighted-randomly-select

add typescript support

https://github.com/masx200/weighted-randomly-select/blob/master/index.d.ts

chance can be provided as Infinity

``js
assert.equal(
9,
Randomly.select([
{
chance: Infinity,
result: 9,
},
{
chance: 6,
result: 19,
},
])
);
`

使用了二分搜索加快查找速度

Installation

NPM:

`
npm install --save @masx200/weighted-randomly-select
`

YarnPkg:

`
yarn add @masx200/weighted-randomly-select
`

deno

`ts
import {} from "https://deno.land/x/masx200_weighted_randomly_select/mod.ts";
`

Examples

`javascript
let Randomly = require("@masx200/weighted-randomly-select");

// Every outcome can be equiprobable
let name = Randomly.select([
{
chance: 1,
result: "John",
},
{
chance: 1,
result: "Mary",
},
]);
// name will be either "John" or "Mary"

// Some outcomes can be more probable than others
let coin = Randomly.select([
{
chance: 1,
result: "Heads",
},
{
chance: 1,
result: "Tails",
},
{
chance: 0.01,
result: "Side",
},
]);
// coin will be either "Heads", "Tails", or "Side"

// Chance values can be any positive number, and result values
// can be anything other than null and undefined
let item = Randomly.select([
{
chance: 0.8,
result: { someField: "someValue" },
},
{
chance: 20,
result: 42,
},
{
chance: 1.5,
result: [3, 1, 5],
},
]);
// item will be either { someField: "someValue" }, 42, or [3, 1, 5]
`

API Reference

Randomly.select(options)

options: an array of objects, each of which having a chance number value and
result value

chance: any positive floating point value (zero is permitted but such an entry
will never be selected)

Note: all chance values must add up to a value greater than zero (i.e. there
should be something to select). These values _do not_ have to add up to 1 or any
other specific value.

Return value: one of the result values in the options array.

Throws errors if any input is invalid.

Randomly.selectWithoutValidation(options)`

Same as above but does _not_ perform any validation on the provided input. If
you're encountering unexpected issues, try using the above method, which does
the same thing but _with_ input validation.