Javascript Reduce Array of Date Value Arrays

Question

I am sure there is a simple solution to this but I can't find it. I am passing an array of [date, value] arrays to Highcharts but I need to add the values for duplicate dates.

I am looking for a new array with the consolidated results.

 [{ "name": "actual", "data": [ [1396242000000, 592.685], [1396242000000, 377.712], [1404104400000, 316.74], [1404104400000, 596.709], [1412053200000, 579.066], [1412053200000, 300.803], [1420005600000, 596.497], [1420005600000, 297.004], [1427778000000, 435.818], [1427778000000, 287.556], [1435640400000, 446.788], [1435640400000, 282.971], [1443589200000, 270.027], [1443589200000, 445.239], [1451541600000, 258.869], [1451541600000, 432.285], [1459400400000, 266.438], [1459400400000, 409.761], [1467262800000, 408.126], [1467262800000, 246.83], [1475211600000, 395.026], [1475211600000, 233.635] ] }, { "name": "forecast", "data": [ [1483164000000, 406.329], [1483164000000, 240.611], [1490936400000, 414.456], [1490936400000, 241.814], [1498798800000, 243.99], [1498798800000, 422.745], [1506747600000, 443.882], [1506747600000, 246.43], [1514700000000, 466.076], [1514700000000, 253.823] ] }] 

Answer 1

 var arr = [{ "name": "actual", "data": [ [1396242000000, 592.685], [1396242000000, 377.712], [1404104400000, 316.74], [1404104400000, 596.709], [1412053200000, 579.066], [1412053200000, 300.803], [1420005600000, 596.497], [1420005600000, 297.004], [1427778000000, 435.818], [1427778000000, 287.556], [1435640400000, 446.788], [1435640400000, 282.971], [1443589200000, 270.027], [1443589200000, 445.239], [1451541600000, 258.869], [1451541600000, 432.285], [1459400400000, 266.438], [1459400400000, 409.761], [1467262800000, 408.126], [1467262800000, 246.83], [1475211600000, 395.026], [1475211600000, 233.635] ] }, { "name": "forecast", "data": [ [1483164000000, 406.329], [1483164000000, 240.611], [1490936400000, 414.456], [1490936400000, 241.814], [1498798800000, 243.99], [1498798800000, 422.745], [1506747600000, 443.882], [1506747600000, 246.43], [1514700000000, 466.076], [1514700000000, 253.823] ] }]; arr.forEach(function(o) { // for each object o in the array var hash = {}; // the hash object, to store the indexes of times in the new array o.data = o.data.reduce(function(newArr, e) { // reduce the data array of the object o var index = hash[e[0]]; // get the index from the hash object of this time (e[0]) if(index === undefined) { // if index is undefined (this time is not hashed yet), then add e to the array and hash its index so it'll be used for duplicates hash[e[0]] = newArr.push(e) - 1; // push returns the new length so the index is the length - 1 } else { // otherwise (the time is already hashed) newArr[index][1] += e[1]; // then add the value of this element (e[1]) to the value of the already hashed element at index index } return newArr; }, []); }); console.log(arr); 

Answer 2

Try this:

 var actual = [ [1396242000000, 592.685], [1396242000000, 377.712], [1404104400000, 316.74], [1404104400000, 596.709], [1412053200000, 579.066], [1412053200000, 300.803], [1420005600000, 596.497], [1420005600000, 297.004], [1427778000000, 435.818], [1427778000000, 287.556], [1435640400000, 446.788], [1435640400000, 282.971], [1443589200000, 270.027], [1443589200000, 445.239], [1451541600000, 258.869], [1451541600000, 432.285], [1459400400000, 266.438], [1459400400000, 409.761], [1467262800000, 408.126], [1467262800000, 246.83], [1475211600000, 395.026], [1475211600000, 233.635]]; var sum = {},result; for (var i=0,c;c=actual[i];++i) { if ( undefined === sum[c[0]] ) { sum[c[0]] = c; } else { sum[c[0]][1] += c[1]; } } result = Object.keys(sum).map(function(val) { return sum[val]}); alert(JSON.stringify(result)); 

Then do the same to the forecast array.

Answer 3

Here is how I would do it (assuming you are able to use ES6):

const data = [
  [1396242000000, 592.685],
  [1396242000000, 377.712],
  [1404104400000, 316.74],
  [1404104400000, 596.709],
  [1412053200000, 579.066],
  [1412053200000, 300.803],
  [1420005600000, 596.497],
  [1420005600000, 297.004],
  [1427778000000, 435.818],
  [1427778000000, 287.556],
  [1435640400000, 446.788],
  [1435640400000, 282.971],
  [1443589200000, 270.027],
  [1443589200000, 445.239],
  [1451541600000, 258.869],
  [1451541600000, 432.285],
  [1459400400000, 266.438],
  [1459400400000, 409.761],
  [1467262800000, 408.126],
  [1467262800000, 246.83],
  [1475211600000, 395.026],
  [1475211600000, 233.635]
];

const forecast = data.reduce((acc, val) => {
  let existingForecast = acc.find(f => f[0] === val[0]);
  existingForecast ? existingForecast[1] += val[1] : acc.push(val);
  return acc;
}, []);

console.log(forecast);