Creating an Array of Cumulative Sum in JavaScript

Creating an array of object with cumulative sum dynamically in javascript

If you want to cumulatively sum every property other than subject, you can do so by mapping the array to new values, keeping an object reference for each running total as you go

const a = [{"subject":"Civil","a":100,"b":50,"c":100},{"subject":"aero","a":200,"b":130,"c":100},{"subject":"tribe","a":100,"b":100,"c":600},{"subject":"solen","a":400,"b":150,"c":100},{"subject":"space","a":100,"b":100,"c":900}]

const cf = {} // store running totals in here
const b = a.map(({ subject, ...props }) => ({
  subject,
  ...Object.fromEntries(Object.entries(props).map(([ key, val ]) => [
    key,
    cf[key] = (cf[key] ?? 0) + val // value is the result of the assignment
  ]))
}))

console.log(b)

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Running sum of the input array in Javascript

Just add first item in array initialization and everything works fine.

function sumOfArray(nums) {
  var output = [nums[0]];        // tip: initialize like let output = [nums?.[0] ?? 0];
  for(let i = 1 ; i < nums.length ; i++) {
    nums[i] = nums[i] + nums[i-1];
    output.push(nums[i]);
  }
  return output;
};

console.log(
  'calling sumOfArray([1,2,3,4])',
  sumOfArray([1,2,3,4])
);

Creating an array of objects with cumulative sum in javascript

You are slicing the original array data, but you need to take the sorted accumulated.

For a shorter approach, you could take a closure over the wanted cumulative sums and add the values and return a new object.

const
    original = [{ end_date: "2020-01-31", invoices_count: 22, month: "2020-01", start_date: "2020-01-01", total_margin: 1000, total_revenue: 1000 }, { end_date: "2020-02-29", invoices_count: 14, month: "2020-02", start_date: "2020-02-01", total_margin: 2000, total_revenue: 2000 }],
    result = original.map(((total_margin, total_revenue) => o => {
        total_margin += o.total_margin;
        total_revenue += o.total_revenue;
        return { ...o, total_margin, total_revenue };
    })(0, 0));

console.log(result);

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Cumulative sum array in Javascript, one is working and one is not

The problem lies in the way you are using cumulativeSum You are trying a function reference and using it between two arrays, because of that when you call the second array the sum already has some value in it. The fix will look in the following way

function tickets(peopleInLine) {
  let changeRequired = [];

  const cumulativeSum = (sum => value => sum += value);

  let cumulativeProfit = peopleInLine.map(cumulativeSum(0));
  cumulativeProfit.splice(0, 0, 0);
  cumulativeProfit.pop();

  for (let i = 0; i < peopleInLine.length; i++) {
      if (peopleInLine[i] === 25) { changeRequired.push(0) }
      else if (peopleInLine[i] === 50) { changeRequired.push(25) }
      else if (peopleInLine[i] === 100) { changeRequired.push(75) }
  };

  let cumulativeOutgoings = changeRequired.map(cumulativeSum(0));
  cumulativeOutgoings.splice(0, 0, 0);
  cumulativeOutgoings.pop();
  return cumulativeOutgoings;
};

Cumulative sum of object properties in array

const arr = [{
  "soldTickets": 0,
  "soldRevenue": 0,
  "playedOffTickets": 0,
  "playedOffRevenue": 0,
  "advanceTickets": 11407,
  "advanceRevenue": 284222.5,
  "occurredAt": "",
  "changeInPeriodTickets": 0,
  "changeInPeriodRevenue": 0,
  "eopAdvanceTickets": 11407,
  "eopAdvanceRevenue": 284222.5
}, {
  "soldTickets": 0,
  "soldRevenue": 0,
  "playedOffTickets": 112,
  "playedOffRevenue": 3151.5,
  "advanceTickets": 0,
  "advanceRevenue": 0,
  "occurredAt": "2022-01-14T00:00:00.000",
  "changeInPeriodTickets": -112,
  "changeInPeriodRevenue": -3151.5,
  "eopAdvanceTickets": -112,
  "eopAdvanceRevenue": -3151.5
}, {
  "soldTickets": 0,
  "soldRevenue": 0,
  "playedOffTickets": 392,
  "playedOffRevenue": 13592,
  "advanceTickets": 0,
  "advanceRevenue": 0,
  "occurredAt": "2022-01-09T00:00:00.000",
  "changeInPeriodTickets": -392,
  "changeInPeriodRevenue": -13592,
  "eopAdvanceTickets": -392,
  "eopAdvanceRevenue": -13592
}, {
  "soldTickets": 0,
  "soldRevenue": 0,
  "playedOffTickets": 502,
  "playedOffRevenue": 18415.5,
  "advanceTickets": 0,
  "advanceRevenue": 0,
  "occurredAt": "2022-01-08T00:00:00.000",
  "changeInPeriodTickets": -502,
  "changeInPeriodRevenue": -18415.5,
  "eopAdvanceTickets": -502,
  "eopAdvanceRevenue": -18415.5
}];

const result = arr.map((obj, index, self) => {
  if (index == 0) return obj;

  const prevO = self[index - 1]
  obj.eopAdvanceTickets+= prevO.eopAdvanceTickets;
  obj.eopAdvanceRevenue+= prevO.eopAdvanceRevenue;
  return obj
});

console.log(result)

Multi dimensional array cumulative sum in Javascript

for (var i=1; i<a.length; i++) {
  for (var z=0; z<a[i].length; z++) {
   a[i][z] = a[i-1]][z] + a[i][z]
  }
}

The array should be updated dynamically as the loop runs on.
This is destructive so it will modify the original array.

Cumulative sum of array, with condition in another array

You're making life far too hard on yourself with all that pushing and reducing and shifting.

function running_total(array, init) {    return array        .map(function(v, i) { return v ===3 ? 0 : v; }) // filter out 3's        .map(function(v)    { return init += v; })   ;}
document.writeln(running_total([1,2,3,4,5], 0));

Cumulative sum of specific keys with array output using reduce

Something like this:

const arr = [{a: 1, b: 2}, {a: 2, b: 4}, {a: 8, b: -1}]

const result = arr.reduce((accumulator, element, index) => {
  if(accumulator.length === 0) {
    accumulator.push(element)
  } else {
    const sum = {};
    for(let i in element) {
      sum[i] = element[i] + (accumulator[index - 1][i] || 0)
    }
    accumulator.push(sum)
  }
  return accumulator
}, [])

console.log(result);