RandomUtils

A set of random helper functions to simplify many common random number needs.

The randoms come in two flavors. Random from JavaScript Math.random and seeded randoms. The seeded randoms alow you to repeat any random sequence using a seed value.

There are two versions

Rand static object and as a set of static functions prefixed with "rand" or for seeded "srand"

'Rand'

To use the static object Rand

Download randomUtils-Rand.js and add to your page

<script src = "randomUtils-Rand.js"></script>

Constant functions

Just include randomUtils.js on your page.

<script src = "randomUtils.js"></script>

ES6

This project is written using ECMAScript6. If your targets are legacy browsers you will need to use something like Babel to ensure compatability.

Seeded random

Seeded random numbers will repeat the same squesnce of random values from the same seed.

Seeded randoms use the object sRand

sRand.max      // read only. Returns the max random integer value
sRand.seed     // Get set the random seed value.
sRand.randI    // read only. Returns a random integer from 0 to sRand.max -1
sRand.rand     // read only. Returns a random float from 0 to < 1

Or usinging Rand

You can use it directly via the above functions, or indirectly using the utility functions.

Each time you get a seeded random value the seed value is updated

To set the seed value

sRand.seed = 1;  // set seed value to 1
sRand.seed = Date.now();  // Less predictable random seed
srandSeed(1);     
srandSeed(Date.now());

or using Rand

Rand.sRand.seed = 1;
Rand.sRand.seed = Date.now();
Rand.seed = 1;
Rand.seed = Date.now();

Notes on random

Please note that seeded randoms are pseudo random using a linear congruential generator. Be aware of its limitations

The random shuffles used in randomUtils.js use a variation on the Fisher-Yates shuffle algorithm.

Random numbers

randI(min, max)    // random integer from and including min to max - 1 
randI(range)       // random integer from and including 0 to range -1    
randI()            // random interger 0 or 1 (like a coin)
rand(min, max)     // random float  min <= float < max 
rand(range)        // random float  0 <= float < range 
rand()             // random float  0 <= float < 1

Seeded randoms

srandI(min, max)    // random integer from and including min to max - 1 
srandI(range)       // random integer from and including 0 to range -1    
srandI()            // random interger 0 or 1 (like a coin)
srand(min, max)     // random float  min <= float < max 
srand(range)        // random float  0 <= float < range 
srand()             // random float  0 <= float < 1

Random odds

Two functions to get a average of 1 in n 'odds' chance of returning true

randOdds(odds)       // Chance of returning true 1/odds 
randOdds()           // Chance of returning true 1/2

Seeded random odds

srandOdds(odds)      // Chance of returning true 1/odds 
srandOdds()          // Chance of returning true 1/2

Random array utilities

Note that empty arrays will return undefined

randItem(array)     // returns a randomly selected item from array
randPick(array)     // return a randomly selected item from array, removing the item from the array.
randPut(array, item)// Adds item randomly to the array. 
                    // Returns the index the item was add. Each call increases the array length by 1
randShuffle(array)  // shuffles an array to randomize the content. 
                    // The shuffle is performed in place, it does not create a new array

Seeded random array functions

randItem(array)     
randPick(array)     
randPut(array, item)
randShuffle(array)

Generate random arrays of integers and floats

randISet(length,min, max)// returns an array of length containg random integer from and including min to max-1 
randISet(length, range)  // returns an array of length containg random integer 0 <= int < range 
randISet(length)         // returns an array of length containg random integers 0 or 1 

randSet(length,min, max) // returns an array of length containg random integer from and including min to max-1 
randSet(length, range)   // returns an array of length containg random integer 0 <= int < range 
randSet(length)          // returns an array of length containg random integers 0 or 1

Seeded version

srandISet(length,min, max) 
srandISet(length, range)  
srandISet(length)         

srandSet(length,min, max) 
srandSet(length, range)   
srandSet(length)

'Rand` Object

List of function signatures. These functions mirror the static functions (above) with some name changes

Rand.int(min, max) 
Rand.int(range) 
Rand.int() 
Rand.float(min, max) 
Rand.float(range) 
Rand.float() 
Rand.odds(odds)
Rand.odds()
Rand.item(array) 
Rand.pick(array)
Rand.put(array, item)
Rand.setOfFloats(length, min, max)
Rand.setOfFloats(length, range)
Rand.setOfFloats(length)
Rand.setOfInts(length, min, max)
Rand.setOfInts(length, range)
Rand.setOfInts(length)
Rand.shuffle(array)

// seeded randoms
Rand.seed
Rand.sInt(min, max) 
Rand.sInt(range) 
Rand.sInt() 
Rand.sFloat(min, max) 
Rand.sFloat(range) 
Rand.sFloat() 
Rand.sOdds(odds)
Rand.sOdds()
Rand.sItem(array) 
Rand.sPick(array)
Rand.sPut(array, item)
Rand.sSetOfFloats(length, min, max)
Rand.sSetOfFloats(length, range)
Rand.sSetOfFloats(length)
Rand.sSetOfInts(length, min, max)
Rand.sSetOfInts(length, range)
Rand.sSetOfInts(length)
Rand.sShuffle(array)

blindman67/RandomUtils