sindresorhus/unique-random

Generate random numbers that are consecutively unique

unique-random

Generate random numbers that are consecutively unique

Useful for things like slideshows where you don't want to have the same slide twice in a row.

Install

$ npm install unique-random

Usage

import uniqueRandom from 'unique-random';

const random = uniqueRandom(1, 10);

console.log(random(), random(), random());
//=> 5 2 6

API

uniqueRandom(minimum, maximum)

Returns a function, that when called, will return a random number that is never the same as the previous.

Related

• unique-random-array - Get consecutively unique elements from an array
• random-int - Generate a random integer
• random-float - Generate a random float
• random-item - Get a random item from an array
• random-obj-key - Get a random key from an object
• random-obj-prop - Get a random property from an object
• unique-random-at-depth - This module with an optional depth argument
• crypto-random-string - Generate a cryptographically strong random string

unique-random's Issues

Support optional depth argument

Currently unique-random only guarantees a unique random value at a depth of 1 in the call history. We can potentially add a third optional argument depth where users can specifiy how many calls deep the returned value should be compared against. So something like

var rand = uniqueRandom(1, 10, 3);

would mean that the returned value would be unique relative to the last 3 calls.

I'm just wondering if this is something you'd be interested in supporting. If so I can PR. I can fork it otherwise.

They repeat... LOL

Heya. I haven't been much active for a long time.

Just tired that package and.. man, several runs and always get a duplicates.

const random = uniqueRandom(1, 100);

console.log(
    Array(30)
        .fill(0)
        .map(() => random())
        .sort((a, b) => a - b)
);

outputs

[
   1,  7,   7, 10, 11, 12, 13, 24, 27,
  38, 39,  41, 43, 47, 51, 52, 59, 62,
  66, 67,  68, 70, 72, 82, 82, 84, 85,
  94, 99, 100
]

this one is not sorted, but at least the 83 is repeated.

[
  41, 16, 61,  2, 30, 56, 71, 20, 24,
  53, 73, 47, 23, 68, 14, 83, 47, 13,
  77, 16, 59, 43, 80, 79, 83, 30, 52,
  12, 97,  7
]

Am I that unlucky or what? 😆

Maybe a better way would be the previousValue to be something like temp array instead and lookup on it.

same value?

const uniqueRandom = require("unique-random")

const random = uniqueRandom(0, 2);

console.log(random(), random(), random());

Add generator method

How we can using it in for loop?

Not Working

Just installed the package, cool idea BTW!
Unfortunately I think it's not working correctly.
the following code:

import uniqueRandom from "unique-random";

const random = uniqueRandom(1, 4);
console.log(random(), random(), random(), random());

sometimes has bad results (i.e 1, 2, 4, 2 or 4, 1, 3, 4). I've noticed it's never the same number twice in a row if that's helpfull.

unique-random-float

... would be a nice lib to have.

Add option to use all number from the range before repeating any numbers

This can be useful, for example, for a music shuffle functionality. It should also ensure numbers across boundaries don't overlap. This would also be useful for slideshows to ensure the images don't show like "image A, image F, image A, …".

Why write this in such a "clever" way?

I was reviewing this function's code, and was surprised by how dense it was written. Just curious if you still support this style of code. (2 and a half years is 20-20?)

Admittedly it is perfectly effective, just far from readable. Like this line:

return prev = num === prev && min !== max ? rand() : num;

😄

Why are my test results repeated?

app.mjs:

import uniqueRandom from 'unique-random';

const random = uniqueRandom(1, 5);

console.log(random(), random(), random());

results:

PS D:\app\node-demo> node app.mjs
3 5 2
PS D:\app\node-demo> node app.mjs
4 1 5
PS D:\app\node-demo> node app.mjs
5 3 2
PS D:\app\node-demo> node app.mjs
2 1 2
PS D:\app\node-demo> node app.mjs
3 2 1
PS D:\app\node-demo> node app.mjs
4 1 2
PS D:\app\node-demo> node app.mjs
4 5 4