How to sum nested array

user_8210918 0
Viewed 299

I have an array like this

var dataSheet = [
    [{price: 200}, {price: 200}, {price: 200}],
    [{price: 200}, {price: 200}],
    [{price: 200}],
]

I would like to sum all the price and a result like this

result = [[600], [400], [200]]

Any help would be appreciated, thanks

javascript
5 Answers

Principle is the same for both nested and flat arrays: just use reduce to get sum of values in array. In your case you just need to apply this mechanism to each nested array in your dataSheet and receive new array of values. Method map is designed exactly creating new array based on values from the source array.

So the correct answer would be to use combination of map and reduce.

var dataSheet = [
    [{price: 200}, {price: 200}, {price: 200}],
    [{price: 200}, {price: 200}],
    [{price: 200}],
]

var result = dataSheet.map(data => data.reduce((acc, obj) => acc += obj.price,0));
console.log(result); // [600, 400, 200]

If you really need to have result like [[600],[400],[200]] (embedded arrays instead of just values, you just need to wrap returned values in [], like this: 

var dataSheet = [
    [{price: 200}, {price: 200}, {price: 200}],
    [{price: 200}, {price: 200}],
    [{price: 200}],
]

var result = dataSheet.map(data => [data.reduce((acc, obj) => acc += obj.price,0)]);
console.log(result); // [[600], [400], [200]]

user_50757550

You could use .map() along with .forEach() function.

var dataSheet = [
    [{price: 200}, {price: 200}, {price: 200}],
    [{price: 200}, {price: 200}],
    [{price: 200}],
]

const res = dataSheet.map(arr => {
  let sum = 0;
  arr.forEach(obj => sum += obj.price);
  return [sum];
});

console.log(res);

user_60943480

I guess map + reduce is what you are looking for :)

const res = dataSheet.map(el => el.reduce((acc, curr) => acc + curr.price, 0));

Or flatMap if you need result as [600, 400, 200]:

const res = dataSheet.flatMap(el => el.reduce((acc, curr) => acc + curr.price, 0));
user_20428270

Use map, reduce and destructuring.

var dataSheet = [
  [{ price: 200 }, { price: 200 }, { price: 200 }],
  [{ price: 200 }, { price: 200 }],
  [{ price: 200 }],
];

const result = dataSheet.map((arr) =>
  Object.values(
    arr.reduce(({ price: acc }, { price }) => ({ price: acc + price }))
  )
);

console.log(result)

user_78994770 

var dataSheet = [
    [{price: 200}, {price: 200}, {price: 200}],
    [{price: 200}, {price: 200}],
    [{price: 200}],
];

var res = dataSheet.reduce((result, row) => 
  result.concat([[row.reduce((sum, element) => 
    sum + element.price, 0)]]), []);

console.log(res);

user_87761220
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