randomless v0.1.3

Randomless

Computers are bad at randomness and so are people. But computers can imitate human ideas about randomness using this little JavaScript library with no dependencies

Purpose

This library provides small functions that generate random numbers or distributions that look random to people, but in reality are not so.

If you ask a person to predict the order of heads and tails when they flip a coin 10 times, they will probably say something like "HTTHTHTHHT". But in reality there will be many clusters, where heads or tails come one after another several times like "HHTHHHHHTT" or even "TTTTTTTTTT".

This library tries to produce random values with few clusters, like a human would.

Install

Install the library

npm i --save randomless

Use it in your code

const randomless = require('randomless')
// or
import randomless from 'randomless'

You can also import individual functions

import getSequence from 'randomless/sequence'
import getNumbers from 'randomless/numbers'
import getGrid from 'randomless/grid'
import Picker from 'randomless/picker'

Functions

• randomless.getNumbers(count: number): number[]
  randomless.getNumbers(count: number, max: number): number[]
  randomless.getNumbers(count: number, min: number, max: number): number[]

  Produces an array of length count of random(less) numbers between min (inclusive, default 0) and max (not inclusive, default 1). Numbers will be distributed more or less evenly around the range. Array is guaranteed to be sorted

  Comparison

  "Truly" random numbers

  console.log(
    // Creating an array of 5 elements and filling it with
    // numbers from 0 to 20 and rounding to two decimal digits
    [...Array(5)].map(() => Math.floor(Math.random() * 20 * 100) / 100).sort()
  )
  // [6.81, 13.22, 17.33, 19.4, 19.84]

  Randomless numbers

  console.log(
    // Also rounding to two decimal digits
    randomless.getNumbers(5, 20).map((n) => Math.floor(n * 100) / 100)
  )
  // [1.71, 6.09, 9.16, 12.69, 18.7]

• randomless.getGrid(count: number, dimensions: number[]): number[]

  Produces a grid with any amount of dimensions that is filled with zeros and contains an amount of ones, specified by count, that are distributed random(less)ly around it.

  Comparison

  In this example I generate 2 grids, where zeros and ones are represented as '—' and '*' symbols respectively.

  "Truly" random grid

  // Creating 8x30 array, filled with '—'
  const grid = [...Array(8)].map(() => [...Array(30)].fill('—'))
  // Randomly placing asteriks around
  for (let i = 0; i < 15; i++) {
    const row = Math.floor(Math.random() * 8)
    const col = Math.floor(Math.random() * 30)
    grid[row][col] = '*'
  }
  // Transforming array into a string
  console.log(grid.map((row) => row.join('')).join('\n'))
  /*
  ——*—————————*————*————————————
  ——————————————***—————————————
  ——————————————————————————*—*—
  ———————————————————————————*——
  ——————————————————————————————
  —————————————————————————*————
  —————————*————————————————————
  ——————————*————————————————*——
  */

  Randomless grid

  const rgrid = randomless.getGrid(15, [8, 30])
  console.log(
    // Transforming array into a string
    rgrid.map((row) => row.map((col) => (col ? '*' : '—')).join('')).join('\n')
  )
  /*
  ————————*—————————————————————
  ——*—————————————————————*———*—
  ————*———————*———————*—————————
  ———————————————*——————————————
  ——————*———————————————————————
  ——————————————————————*———————
  ——*———————————*———*———————————
  ——————————*————*——————————————
  */

• randomless.getSequence<T>(count: number, symbols: T[]): T[]

  Produces a random(less) sequence of length, given by count, that consists of given symbols.

  Comparison

  Example with heads and tails from the description of the library:

  "Truly" random distribution

  console.log(
    // Creating array with 10 elements and filling it randomly with 'T' or 'H'
    [...Array(10)].map(() => ['T', 'H'][Math.round(Math.random())]).join('')
  )
  // "HHHHHHTTTT"

  Randomless distribution

  console.log(randomless.getSequence(10, ['H', 'T']).join(''))
  // "HTTHHTHTTT"

The library also provides a small class that generates such sequences infinitely

class Picker<T> {
  constructor(symbols: T[])
  next(): T
}

Example

const picker = new Picker(['H', 'T'])

// Print randomless heads and tails till the end of times
while (true) {
  console.log(picker.next())
}

Note, that this class does not implement JavaScript iterator protocol