Sum all Elements in each Array on Multiple Dynamic Arrays

Question

How do we sum each array element in multiple arrays

ex : [[2, 1], [1, 4]]
output : [3], [5]

In this code is the sum based on the index in each array

const in_out = [
  [2, 1],
  [1, 4]
]

function calculate(arr) {
  a = arr.reduce((prev, curr) => prev + curr[idx = 0], 0)
  b = arr.reduce((prev, curr) => prev + curr[idx = 1], 0)
  c = [a + b]
  return c
}

console.log(calculate(in_out))

and what I want is summation based on each array, and dynamic "in_out" variable like this

[2, 1] = 3 and [1, 4] = 5

console.log(calculate (in_out [[2, 1], [1, 4]] ) );

and the output

[8]

stackoverflow.com/questions/39492385/… |It's a duplicate I guessed — user17899000
– user17899000, Commented Jan 12, 2022 at 6:21
function calculate(arr) { return arr.map(sub =>[sub.reduce((acc,num)=>acc+num)]) } does this solve your problem? — Saeed Shamloo
– Saeed Shamloo, Commented Jan 12, 2022 at 6:37
@SaeedShamloo yes, its helped me alot, but when im trying to add console.log(calculate (in_out [[2, 1], [1, 4]] ) ); it doesnt work — morinmay
– morinmay, Commented Jan 12, 2022 at 6:46

Rahul Kumar · Accepted Answer · 2022-01-12 06:30:15Z

1

Use Array.reduce() method 2 times, the outer one will give you the transformed array and the nested one will give you the sum.

const list = [
  [2, 1],
  [1, 4]
];

function calculate(arr) {
  return arr.reduce((acc, items) => acc.concat(items.reduce((sum, curr) => sum + curr, 0)), [])
}

console.log(calculate(list))

answered Jan 12, 2022 at 6:30

Rahul Kumar

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Comments

Eko Muhammad Rilo Pembudi · Accepted Answer · 2022-01-12 07:40:49Z

0

Conventional way!

function sumTwoDimensi(arr){
  var arrSum = []; 

  for(let i = 0; i < arr.length; i++) {
    var sum = 0;
    for (let j = 0; j < arr[i].length; j++) {
      sum = (sum+arr[i][j]);
    }
    arrSum[i] = sum;
  }

  return arrSum
}

Then to calculate all of it, just this function:

function sumArr(ar) {
  var sum = 0;
  for (var i = 0; i < ar.length; i++) {
    sum += ar[i];
  }
  return sum;
}

Example for use it:

console.log(sumTwoDimensi(in_out));
console.log(sumArr(sumTwoDimensi(in_out)));

Just copy it!

edited Jan 12, 2022 at 7:40

answered Jan 12, 2022 at 6:42

Eko Muhammad Rilo Pembudi

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6 Comments

morinmay Over a year ago

and how to summarize all value? ex: 3 + 5 =8

Eko Muhammad Rilo Pembudi Over a year ago

i have edit it, sorry i missed on it. U can try it now

morinmay Over a year ago

when im changing the operator "+" to "-", values are changed to negative not substract ex: [2 - 1] it should be "1" not "-3" can you explain to me? why this happen?

Eko Muhammad Rilo Pembudi Over a year ago

Because this is only for sum, i think you need use another function for substraction.. the explanation for it, because the initialize of sum is 0, it will be [ 0 - firstArray], it will be wrong answer

Eko Muhammad Rilo Pembudi Over a year ago

But it will be trouble when we have array like this [[3, 4, 5], [5, 7]]

|

Nkubito Pacis · Accepted Answer · 2022-01-12 06:44:40Z

0

You can try something like this

function in_out(arr){
  var output = []
  arr.map(arrElement=>{
     var sum = 0;
     arrElement.map(el=>{
        sum += el
     })
     output.push([sum])
  })
  return output
}
console.log(in_out([[2,1],[1,4]]))

answered Jan 12, 2022 at 6:44

Nkubito Pacis

814 bronze badges

Comments

A1exandr Belan · Accepted Answer · 2022-01-12 06:51:36Z

0

Just map and reduce:

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

const calculate = (data) => 
  data.map((arr) => 
    arr.reduce((sum, num) => sum + num, 0)
  );
  
console.log(calculate(in_out));

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

edited Jan 12, 2022 at 6:51

answered Jan 12, 2022 at 6:41

A1exandr Belan

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