Recreate array in javascript on the basis of sum of column values in Javascript

Question

I have  an array like this having data as number values. I have to find out the sum of column values.

const data = [
    [{'data':0},{'data':3},{'data':1},{'data':0}],
    [{'data':1},{'data':1},{'data':1},{'data':1}],
    [{'data':2},{'data':2},{'data':2},{'data':2}],
    [{'data':3},{'data':3},{'data':3},{'data':3}]
];

I have to calculate the sum of records at 0 index together, 1 index together and 2 index together. Result should be calculate on the basis of column values sum.

My approach on this but it is not working alright. Giving me the different results. What is the wrong approach I am doing here.Also, I was getting result[i] as undefined so I put it in a condition with initialize empty array. But, it doesn't seems to be right logic to me.

for( let i = 0; i < data.length; i++ ) {
    let sum = 0;
    for( let j = 0; j < data[i].length; j++ ) {
    if( !result[i] ){
        result[i] = [];
    }
    sum = sum+data[i][j].data;
    result[i][j] = data[i][j];
    index++;
    }
}

Expected result on the basis of column values sum. e.g. first colum values are 0, 1,2,3 the sum will be 6.

let expectedResult = [6,9,8,6]

CertainPerformance · Accepted Answer · 2021-01-14 05:52:48Z

4

I wouldn't try to calculate the sum inside an individual iteration - instead, on each iteration, add to the associated index in the output array. There's no need for a nested result structure, all you need is a single array containing numbers.

const data = [
    [{'data':0},{'data':3},{'data':1},{'data':0}],
    [{'data':1},{'data':1},{'data':1},{'data':1}],
    [{'data':2},{'data':2},{'data':2},{'data':2}],
    [{'data':3},{'data':3},{'data':3},{'data':3}]
];

const output = [];
for (const subarr of data) {
  subarr.forEach(({ data }, i) => {
    output[i] = (output[i] || 0) + data;
  });
}
console.log(output);

answered Jan 14, 2021 at 5:52

CertainPerformance

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1 Comment

Vikash Dhiman Over a year ago

I have the data like this 16 arrays I have

John · Accepted Answer · 2021-01-14 05:54:14Z

3

Just iterate it properly

var data = [
    [{'data':0},{'data':3},{'data':1},{'data':0}],
    [{'data':1},{'data':1},{'data':1},{'data':1}],
    [{'data':2},{'data':2},{'data':2},{'data':2}],
    [{'data':3},{'data':3},{'data':3},{'data':3}]
];


var result = Array();

for(let i = 0; i < data[0].length; i++)
{
  for(let k = 0; k < data.length; k++)
  {
    result[i]   = result[i] || 0;
    result[i] += data[k][i].data;
  }
}

console.log(result);

answered Jan 14, 2021 at 5:54

John

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