How to create new array with begins and limit numbers in Javascript

Question

I want to create with transforming old array.

arr1 = [ 4,  26,  40,  53,  58,  68,  73,  86, 91, 114, 119, 132, 137, 147, 152, 165, 170, 183, 188, 201, 206, 208, 215, 220, 233, 238, 250, 255, 267, 272, 284, 289, 301, 306, 318, 323 ]

I want to create like

newArr = [[4,5,6,7,8,9,10 ..., 24,25], [26,27,28 ..., 39], [40,...,52], ...]

As you see in arr1, the number is the beginning, and the next item - 1 is the last number. How I can do like this. The last number is 325 in arr1 I tried chunk_array, but it does not work.

can you be more clear, and include that part of the desired output in your question instead of ...]? — trincot
– trincot, Commented Oct 9, 2021 at 12:02

Nenad Vracar · Accepted Answer · 2021-10-09 12:00:20Z

2

You could use map and Array.from and then get all except the last one with slice(0, -1).

const arr = [4, 26, 40, 53, 58, 68, 73, 86, 91, 114, 119, 132, 137, 147, 152, 165, 170, 183, 188, 201, 206, 208, 215, 220, 233, 238, 250, 255, 267, 272, 284, 289, 301, 306, 318, 323]
const result = arr.map((e, i) => Array.from(Array((arr[i + 1] || e) - e), (_, j) => e + j)).slice(0, -1)
console.log(result)

answered Oct 9, 2021 at 12:00

Nenad Vracar

122k16 gold badges160 silver badges184 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

DecPK · Accepted Answer · 2021-10-09 12:20:17Z

1

1) You can use map and Array.from to achieve the desired result

const arr1 = [
  4, 26, 40, 53, 58, 68, 73, 86, 91, 114, 119, 132, 137, 147, 152, 165, 170,
  183, 188, 201, 206, 208, 215, 220, 233, 238, 250, 255, 267, 272, 284, 289,
  301, 306, 318, 323,
];

const result = arr1.map((el, i, src) => {
  const start = el, end = src[i + 1];
  return Array.from({ length: end - start }, (_, i) => i + start);
});

result.pop();
console.log(result);

2) You can also do as

const arr1 = [
  4, 26, 40, 53, 58, 68, 73, 86, 91, 114, 119, 132, 137, 147, 152, 165, 170,
  183, 188, 201, 206, 208, 215, 220, 233, 238, 250, 255, 267, 272, 284, 289,
  301, 306, 318, 323,
];

const result = arr1.map((el, i, src) => {
  const start = el, end = src[i + 1] ?? start;
  return Array(end - start)
    .fill(0)
    .map((_, i) => i + start);
});

result.pop();
console.log(result);

3) You can also use reduce here:

const arr1 = [
  4, 26, 40, 53, 58, 68, 73, 86, 91, 114, 119, 132, 137, 147, 152, 165, 170,
  183, 188, 201, 206, 208, 215, 220, 233, 238, 250, 255, 267, 272, 284, 289,
  301, 306, 318, 323,
];

const result = arr1.reduce((acc, start, i, src) => {
  const temp = Array((src[i + 1] ?? start) - start)
    .fill(0)
    .map((_, i) => i + start);
  if (temp.length) acc.push(temp);
  return acc;
}, []);

console.log(result);

edited Oct 9, 2021 at 12:20

answered Oct 9, 2021 at 12:03

DecPK

25.4k6 gold badges32 silver badges46 bronze badges

2 Comments

trincot Over a year ago

Essentially the same answer as was already posted.

Andy Over a year ago

Imagine two coders coming up with two very similar answers within minutes of each other.

navnath · Accepted Answer · 2021-10-09 12:38:57Z

0

const data = [ 4,  26,  40,  53,  58,  68,  73,  86, 91, 114, 119, 132, 137, 147, 152, 165, 170, 183, 188, 201, 206, 208, 215, 220, 233, 238, 250, 255, 267, 272, 284, 289, 301, 306, 318, 323 ]

const result = data.map((n, index, array) => Array.from({ length: ( array[index+1] || n+1 ) - n }, (_, i) => i+n));

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0 }

answered Oct 9, 2021 at 12:38

navnath

3,7241 gold badge13 silver badges20 bronze badges

1 Comment

navnath Over a year ago

Shouldn't be last number 323 included in the result?

Collectives™ on Stack Overflow

How to create new array with begins and limit numbers in Javascript

3 Answers 3

Comments

2 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

2 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related