Taking one array and randomizing it into another array

Question

I have two arrays (representing a deck of cards), one filled with the values 1-52, and another filled with nothing. I want to take the position randomly from the first array and take that object and put it into the next spot available in the randomized array. I have this so far:

var shufdeck = new Array(); while(sufdeck.length < 52) { i = Math.floor(Math.random()*52); //shufdeck[0] = deck[i] etc. }

I'm not sure if I should be using splice or something else to take it out of the first array and put it into the second. If possible shufdeck[] should be filled and deck[] would be empty.

How can I shuffle an array?

Do you care whether the original deck[] is empty at the end, or do you only need shufdeck[] to be a shuffled version of deck[]? — gpcz
– gpcz, Commented Mar 13, 2014 at 0:14
I only need shufdeck[] to be filled. the original deck[] should be empty if possible. — user3413170
– user3413170, Commented Mar 13, 2014 at 0:15
Thanks, I found stackoverflow.com/questions/6274339/… to be more helpful! — user3413170
– user3413170, Commented Mar 13, 2014 at 0:21

RobG · Accepted Answer · 2014-03-13 01:01:44Z

Yes, you should splice out the chosen card, so:

var shuffledDeck = []; while (deck.length) { shuffledDeck.push(deck.splice(Math.random()*deck.length | 0, 1)[0]); }

or to be a little more efficient:

var i = deck.length; while (i) { shuffledDeck.push(deck.splice(Math.random()*i-- | 0, 1)[0]); }

Note that this will destroy deck. If you don't want that, copy it first:

var deckToShuffle = deck.slice();

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Taking one array and randomizing it into another array

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