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I have an array something like this..

 var array = [2,a,b,3]

i want to arrange that so it can show console array like this

//console.log
[1,a,b,1]
[1,a,b,2]
[1,a,b,3]
[2,a,b,1]
[2,a,b,2]
[2,a,b,3]

update

what if i want loop every number in array, and what if that array not static but dynamic 

var array = [2,'a','b',3]
var array = [2,'a',4,'c','b',3]
var array = [2,'a']

and i want put that console result in array

if any body want know why i do this this cos i have nasted array i save all Object.prototypename inside an array so i can call it leater,

this axample 

var data = [{a:0,b:[{c:0},{c:0}]},{a:0,b:[{c:0},{c:0}]}]

i have function so it will return

[2,a,b,2,c]

then i can call it

data [2][a][b][2][c]

my function can return anything acording to selected data so i want to make this, but stuck in here

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6
  • 2
    Ok, you have one array then you want 5 more arrays? Commented Jun 22, 2017 at 3:11
  • 2
    What about [1, c, 4, d, e, 2]?? Commented Jun 22, 2017 at 3:12
  • What are you trying to do? It doesn't seem like the output you want has anything to do with the original array. Commented Jun 22, 2017 at 3:12
  • 1
    And what about negative numbers such as: [-5, c]?? Commented Jun 22, 2017 at 3:14
  • that array is hold the location of element in my Object array, that mean in my object Array have 2 object Object and have element a and b that b is array that contains 3 object Commented Jun 22, 2017 at 3:16

5 Answers 5

Reset to default
2 

function clone(arr, i, values) {
    var newArr = arr.slice();
    values.forEach(v => newArr[v.index] = Math.floor(i / v.breaker) % v.max + 1);
    return newArr;
}

function result(arr) {
    var n = 1,
        values = arr.reduceRight((acc, e, i) => {
            if(typeof e === "number") {
                acc.push({
                    index: i,
                    max: e,
                    breaker: n
                });
                n *= e;
            }
            return acc;
        }, []);
    
    var res = [];
    for(var i = 0; i < n; i++) {
        res.push(clone(arr, i, values));
    }
    return res;
}

console.log( result([2,'a','b',3,4]) );

Explaining with an example:

Let arr be [2, a, 3].

Then values will be:

[
    {
        index: 0,
        max: 2,
        breaker: 3
    },
    {
        index: 2,
        max: 3,
        breaker: 1
    }
]

And n, the number of permutations is: 2 * 3 === 6.

Usage of the breaker property:

When the clone function clones the array, it will update the clone's numbers according to the index of the current permutation i.

The breaker, makes it possible to not increment the early (first-to-encounter) numbers more frequently. To increment a number we need to wait N times (permutaions) where N is the number of permutations of the numbers on the left of this number. In the above example: we update 2's place every 3 permutations (everytime 3's place has completed a cycle).

If the array is: [2, 3, 7] then:

  • To increment 7's number we won't have to wait. It will just cycle, uninterruptely, untill all permutations are done. Thus breaker === 1.
  • To increment 3' number we'll have to wait for 7's to complete a cycle. 7's will take 7 permutations to complete one, thus breaker === 7.
  • To increment 2's number, we'll have to wait for 3's to complete a cycle which also have to wait for 7's to complete one. So we have to wait 3 times 7, thus breaker === 3 * 7 === 21.

The breaker of a number is just the number of permutations the number on its left takes to complete a cycle.

Explaining the clone function:

The clone function takes:

  • arr: the array to be cloned and modified according to the current permutation's index.
  • i: the current permutation's index.
  • values: the array of the data objects that contain informations about all the numbers in the array arr (the index of the number, the maximum value it can take, its breaker value).

The function starts by creating a clone for the array (var newArr = arr.slice();). Then loop over all the data objects in the values array, calculating the value of the number:

theValueOfTheNumber = (indexOfCurrentPermutation / breaker) % maximumValuePossible + 1;

We start by dividing the index of the current permutation by the breaker to ensure that the value won't be incremented untill the number on its left completed a cycle (If it takes 3 permutations to be incremented, then 0 / 3, 1 / 3, 2 / 3 will all be equal to 0 when applying Math.floor). Then we clamp the value so it won't exceed the maximum value allowed for it (the initial value) by using the Modulo operator % and the +1 so values will be in the range [1 -> maximumValuePossible].

Explanation of result function:

This function is simple, it just gather needed information such as the number of all permutations n and the values array.

It uses reduceRight to loop over the array from right to left, thus when encountering a number, we just assign the accumulated n (which will be the number of permutations on its left) as its breaker value.

After, we gather the informations, we just create a loop that loops the exact number of permutations, calling clone and pushing it returned value into the result array.

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1 Comment

mate, dude, sir mr, cmoon really-really, aghhh.... you save me thanks, i really sad, thank you, good explaination, thanks all of you thanks stackoverflow
2

if your array fixed:

for(i = 1; i <= 2; i++) {
  for(j = 1; j <= 3; j++) {
    console.log("[" + i + ",a,b," + j +"]");
  }
}
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3 Comments

thanks, but my array not fix, it maybe become [1, c, 4, d, e, 2] or any things,
can you explain more detail your question?
@Frog Update your question to include that input and show what the output would look like.
2

You will need to iterate through the array:

var array = [2, 'a', 'b', 3];
for(i = 1; i <= array[0]; i++) {
  for(j = 1; j <= array[3]; j++) {
    console.log("[" + i + array[1] + array[2] + j +"]");
  }
}

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2 Comments

nice, but how about dynamic array, cos that is Object.propertyName, so it will not negative always real number, and strings, how if that array is dynamic?
i try using isNaN, to define if its is number, if number loop that, i try but faill, if that array change dynamicly
2

How about:

var len = array.length;

for(i = 1; i <= array[0]; i++) {
    for(j = 1; j <= array[len-1]; j++) {
        console.log([i].concat( array.slice(1, len-1), [j]))
    }
}

[ 1, 'a', 'b', 1 ]
[ 1, 'a', 'b', 2 ]
[ 1, 'a', 'b', 3 ]
[ 2, 'a', 'b', 1 ]
[ 2, 'a', 'b', 2 ]
[ 2, 'a', 'b', 3 ]
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2 Comments

thanks, but if i change the array to diferent value like [1, 'c', 4, 'd', 'e', 2], the sistem faill, can it running dynamicly? to any array input
What output do you want with the customized array given, do you want to loop over 4 as well? When I run the array with the code, it doesn't fail, it gives two arrays.
1

Edit: My brain is about done for tonight but as I blankly stare at your question trying to figure out what you are trying to do and why you are trying to do it I started to think of a potential approach that is better than my current answer.

If the letter values are static, what you really care about is building a matrix based on the numbers. If you have [2,3] you want a two by three matrix with static letters in between. If you have a [3,3] you want a matrix of 9 rows of 2 items. [2,3,2] would be 12 rows of 3 items.

So if that's a correct assumption [2,"a","b",3,"c",2] would end up looking something like:

[1,1,1]
[1,1,2]
[1,2,1]
[1,2,2]
[1,3,1]
[1,3,2]
[2,1,1]
[2,1,2]
[2,2,1]
[2,2,2]
[2,3,1]
[2,3,2]

Then adding the static content back in:

[1,"a","b",1,"c",1]
[1,"a","b",1,"c",2]
[1,"a","b",2,"c",1]
[1,"a","b",2,"c",2]
[1,"a","b",3,"c",1]
[1,"a","b",3,"c",2]
[2,"a","b",1,"c",1]
[2,"a","b",1,"c",2]
[2,"a","b",2,"c",1]
[2,"a","b",2,"c",2]
[2,"a","b",3,"c",1]
[2,"a","b",3,"c",2]

Is that remotely what you're looking for? Are the letters irrelevant other than that they need to show up in the final output?

Here's where I'm leaving off for tonight:

const data = [2, "a", "b", 3];

// Find the numbers
const numericData = data.filter(item => typeof item === 'number');
console.log(numericData); // [2,3]

// Build the matrix
const matrix = Array(2).fill()
                       .map(()=>Array(3).fill(0));
console.table(matrix);

// Populate the matrix

// Add static content back in

Original answer:

There's got to be a better way but here's one way.

const data = [2, "a", "b", 3];

let output = [];

for (let x = 1; x <= data[0]; x++) {
  for (let y = 1; y <= data[3]; y++) {
    output.push([x, "a", "b", y]);
  }
}

console.log(output);

Yields:

[
[1,"a","b",1],
[1,"a","b",2],
[1,"a","b",3],
[2,"a","b",1],
[2,"a","b",2],
[2,"a","b",3]
]
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4 Comments

nice one hold it on array, how about dynamic data?, so if i change data to [1, c, 4, d, e, 2] it can still give me the result
Update your question to show what the output should look like in that scenario. I have a solution partially completed for dynamic but it is complicated as hell. I'm trying to use reduce to do what I think will work.
See my updated answer/now question with assumptions.
so i can make forEach function to show data[2][a][b][3][2] to call data inside my nasted array, i try make some thing dynamicly so user can choose the data

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