How do I create (d) elements arrays out of another array of (n > d) elements?

user_13807689 0
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For example, we have the array:

let arr = [1,2,3,4,5,6,7,8,9] //(n = 9)

Now i want to create maximum amount of arrays of d = 5:

Array1: arr1 = [1,2,3,4,5]

Array2: arr2 = [2,3,4,5,6]

Array3: arr3 = [3,4,5,6,7]

Array4: arr4 = [4,5,6,7,8]

Array5: arr5 = [5,6,7,8,9]

How can I do that?

arrays loops javascript
3 Answers

Simple for loop and array.slice should work in this case:

let arr = [1,2,3,4,5,6,7,8,9];
let d = 5;

let result = [];

for(let i = 0; i <= (arr.length - d); i++){
   result.push(arr.slice(i, d+i));
}

console.log(result);

user_62389770

I will assume that you want to keep your "sub-arrays" in the same order as your initial array?:

const arr = [1,2,3,4,5,6,7,8,9];

console.log(generateSubArrs(arr, 5));

function generateSubArrs(arr, d){
  const outputArrs = [];
  const n = arr.length;
  for (let i = 0; i <= (n - d); i++){
    const tempArr = [];
    for (let j = 0; j < d; j++){
      tempArr.push(arr[i + j]);
    }
    outputArrs.push(tempArr);
  }
  return outputArrs;
}

Output:

[
  [    1,    2,    3,    4,    5  ],
  [    2,    3,    4,    5,    6  ],
  [    3,    4,    5,    6,    7  ],
  [    4,    5,    6,    7,    8  ],
  [    5,    6,    7,    8,    9  ]
]
user_97925940

One more solution using a reducer:

const arr = [1, 2, 3, 4, 5, 6, 7, 8, 9]
const size = 5

const result = arr.reduce((acc, _, i) => {
  if (i <= arr.length - size) acc.push(arr.slice(i, i + size))
  return acc
}, [])

console.log(result)

Caveat: if size > arr.length, result will be an empty array.

user_10798690
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