multiple arrays into one array

Question

I need help with the five.myArraysCombined property.

I need it to equal just 1 array (which it currently does in fiddle) and I need it to NOT add any numbers together. (so each number in the array shouldn't be over 20, just like no number in the other arrays are over 20)

http://jsfiddle.net/Dc6HN/1/

For example, if the five arrays are like this

five.myArray1 = [7,2,9,19,3];
five.myArray2 = [6,18,8,1,7];
five.myArray3 = [7,19,4,8,2];
five.myArray4 = [11,9,1,14,5];
five.myArray5 = [3,18,8,9,2];

then the all those arrays combined should be like this

five.myArraysCombined = [7,2,9,19,3,6,18,8,1,7,7,19,4,8,2,11,9,1,14,5,3,18,8,9,2];

Relevant code :

function theNumberClass() {
    this.myArray = [[],[],[],[],[]];
    this.myArraysCombined = [];
}
var five = new theNumberClass();

function prePickNumbers(objName, theNum, theSumNum, theMaxNum, theMinNum) {
    var zzz = [];
    for (var x = 0; x < theNum; x += 1) {
    pickNumbers(objName.myArray[x], theNum, theSumNum, theMaxNum, theMinNum);
      zzz += objName.myArray[x];
    }
    objName.myArraysCombined.push(zzz);
}

prePickNumbers(five, 5, 40, 20, 1);

My latest attempt was with var zzz and then pushing it to the property, but when I do that it adds up the numbers in the array at times, which is not what I need.

I've also tried several attempts using the .concat(), but it seems to turn it into a string and sometimes also adds up the numbers.

You mean you have some arrays and you want to get one array with their elements ? — Denys Séguret
– Denys Séguret, Commented Jan 14, 2014 at 13:11
@dystroy I think so, but not sure what you mean. For this I have 5 arrays. Each array is comprised of 5 numbers. This is generated randomly. So once the 5 arrays are generated, I want to make 1 array that includes each number in the 5 arrays. — CRABOLO
– CRABOLO, Commented Jan 14, 2014 at 13:13
@dystroy The five.myArraysCombined should be 1 array that includes 25 numbers. Duplicates are fine in that array. — CRABOLO
– CRABOLO, Commented Jan 14, 2014 at 13:14

Denys Séguret · Accepted Answer · 2014-01-14 13:37:28Z

3

Suppose you have those arrays :

var a = [1, 2, 3]
var b = [4, 5, 6]
var c = [8]

Then you can get a merge of all those with

var all = [].concat.apply([],[a,b,c])

or with

var all = [a,b,c].reduce(function(merged, arr){ return merged.concat(arr) })

In both cases you get

[1, 2, 3, 4, 5, 6, 8]

The first solution is simpler, the second one is more extensible if you want, for example, to remove duplicate or do any kind of filtering/transformation.

edited Jan 14, 2014 at 13:37

answered Jan 14, 2014 at 13:15

Denys Séguret

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2 Comments

Givi Over a year ago

Maybe I'm wrong, but second argument of reduce is useless, since there's no need to use initial value.

Scimonster Over a year ago

@AlienArrays This would work with a variable number of arrays as well.

drew_w · Accepted Answer · 2014-01-14 13:15:18Z

I would guess that the issue is the "+=" operator. This operator is used to sum values, not add new elements to an array. Take the following line of code as an example:

zzz += objName.myArray[x];

What I am guessing is that "myArray[x]" is getting added to the value of zzz instead of getting appended to the end of the array. When adding elements to an array in javascript, push is the best option. A better way to write this line is:

zzz.push(objName.myArray[x]);

The question was a bit confusing so I'm not sure if this is what you are looking for but hopefully it will help anyways.

Yea, I guess it didn't work like I needed. My fault for testing the array incorrectly. I asked another question here stackoverflow.com/questions/21118706/… and got it fixed. Thanks though, and thanks for your time.

Scimonster · Accepted Answer · 2014-01-14 13:17:55Z

1

five.reduce(function(o,n){return o.concat(n)},[])

This will reduce the array to a single value, in this case an array of numbers. You can look up Array.reduce() on MDN for more info.

answered Jan 14, 2014 at 13:17

Scimonster

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Comments

CRABOLO · Accepted Answer · 2014-01-17 10:46:57Z

After many hours trying all suggestions left on this thread and another one, and trying multiple other things. I think I finally found a very simple way to do this. And it's the only way I tried that works 100% like I want.

http://jsfiddle.net/Dc6HN/2/

function prePickNumbers(objName, theNum, theSumNum, theMaxNum, theMinNum) {
    for (var x = 0; x < theNum; x += 1) {
    pickNumbers(objName.myArray[x], theNum, theSumNum, theMaxNum, theMinNum);
    objName.myArraysCombined.push(objName.myArray[x]);
}
   objName.myArraysCombined = objName.myArraysCombined.toString();
   objName.myArraysCombined = objName.myArraysCombined.split(',');
}

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