convert array of objects to yearly and monthly using javascript reduce method

Question

Problem Statement :

I have an array of objects with month , sales & orders as attributes. now, I want to create a function like following. which can provide result based on the argument.

function aggregate(json_data , yearly)
{
  // This function could return an array of objects like following
  // [ { Month : 2014 , Sales : x , Amount : x},
  //   { Month : 2015 , Sales : x , Amount : x }
  //  ]
};

If the user pass argument as quarter , then data should aggregate quarterly

function aggregate(json_data , quarterly)
{
  // This function could return an array of objects
  // [ { Month : 2014Q1 , Sales : x , Amount : x},
  //   { Month : 2014Q2 , Sales : x , Amount : x }
  //    ............
  //    ............
  //  ]
}

Sample Data

 var data = [
  {
     Month: 201401,
     Sales: 15,
     Orders: 4
  },
  {
     Month: 201402,
     Sales: 12,
     Orders: 3

  },
  {
     Month: 201403,
     Sales  : 16,
     Orders: 5

  },
  {
     Month: 201404,
     Sales: 12,
     Orders: 2
  },

  {
     Month: 201405,
     Sales: 12,
     Orders: 4
  },

  {
     Month: 201406,
     Sales: 10,
     Orders: 3
  },

  {
     Month: 201407,
     Sales: 15,
     Orders: 2
  },

  {
     Month: 201408,
     Sales: 14,
     Orders: 3
  },

  {
     Month: 201409,
     Sales: 13,
     Orders: 6
  },

  {
     Month: 201410,
     Sales: 13,
     Orders: 5
  },

  {
     Month: 201411,
     Sales: 12,
     Orders: 2
  },

  {
     Month: 201412,
     Sales: 11,
     Orders: 4
  },
  {
     Month: 201501,
     Sales: 15,
     Orders: 4
  },
  {
     Month: 201502,
     Sales: 12,
     Orders: 6

  },
  {
     Month: 201503,
     Sales  : 6,
     Orders: 5

  },
  {
     Month: 201504,
     Sales: 10,
     Orders: 11
  },

  {
     Month: 201505,
     Sales: 10,
     Orders: 2
  },

  {
     Month: 201506,
     Sales: 10,
     Orders: 3
  },

  {
     Month: 201507,
     Sales: 10,
     Orders: 1
  },

  {
     Month: 201508,
     Sales: 10,
     Orders: 4
  },

  {
     Month: 201509,
     Sales: 10,
     Orders: 2
  },

  {
     Month: 201510,
     Sales: 10,
     Orders: 3
  },

  {
     Month: 201511,
     Sales: 10,
     Orders: 2
  },

  {
     Month: 201512,
     Sales: 10,
     Orders: 1
  }
];

Please advice, If there is any other suggestions either to adapt the question.

Someone has suggested that it is a duplicated question. However, I am working with date object. ( Please check the duplicate link before suggesting)

Answer 1

You could use a hash table and use a key based on the wanted yearly or quarterly aggregation of the data.

This proposal uses Month as string.

 function aggregate(array, quarterly) { var hash = Object.create(null), result = []; data.forEach(function (o) { var [period, month] = o.Month.toString().split(/(?=..$)/); if (quarterly) { period += 'Q' + Math.floor((+month + 2) / 3); } if (!hash[period]) { hash[period] = { period, Sales: 0, Orders: 0 }; result.push(hash[period]); } hash[period].Sales += o.Sales; hash[period].Orders += o.Orders; }); return result; } var data = [{ Month: 201401, Sales: 15, Orders: 4 }, { Month: 201402, Sales: 12, Orders: 3 }, { Month: 201403, Sales: 16, Orders: 5 }, { Month: 201404, Sales: 12, Orders: 2 }, { Month: 201405, Sales: 12, Orders: 4 }, { Month: 201406, Sales: 10, Orders: 3 }, { Month: 201407, Sales: 15, Orders: 2 }, { Month: 201408, Sales: 14, Orders: 3 }, { Month: 201409, Sales: 13, Orders: 6 }, { Month: 201410, Sales: 13, Orders: 5 }, { Month: 201411, Sales: 12, Orders: 2 }, { Month: 201412, Sales: 11, Orders: 4 }, { Month: 201501, Sales: 15, Orders: 4 }, { Month: 201502, Sales: 12, Orders: 6 }, { Month: 201503, Sales: 6, Orders: 5 }, { Month: 201504, Sales: 10, Orders: 11 }, { Month: 201505, Sales: 10, Orders: 2 }, { Month: 201506, Sales: 10, Orders: 3 }, { Month: 201507, Sales: 10, Orders: 1 }, { Month: 201508, Sales: 10, Orders: 4 }, { Month: 201509, Sales: 10, Orders: 2 }, { Month: 201510, Sales: 10, Orders: 3 }, { Month: 201511, Sales: 10, Orders: 2 }, { Month: 201512, Sales: 10, Orders: 1 }]; console.log(aggregate(data)); console.log(aggregate(data, true)); 

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

Answer 2

Not entirely sure if it's the same problem, but I recently had to solve what seems, at least, a very similar problem. I had an array of objects with a date and a value, such as this:

statsData = [
      { x: randomDate, y: 1 },
      { x: randomDate, y: 2 },
      { x: randomDate, y: 1 },
      { x: randomDate, y: 4 },
      { x: randomDate, y: 3 },
      { x: randomDate, y: 2 },
      { x: randomDate, y: 1 },
      { x: randomDate, y: 4 },
      { x: randomDate, y: 6 },
      { x: randomDate, y: 5 },
      { x: randomDate, y: 1 }
]

And I needed to reduce it, so that all the objects with the same month are grouped together under one object that adds all the values of that month.

What I did was, first to sort them, in case they don't come chronollogically ordered:

sortData(data) {
    return data.sort((a, b) => {
      return +a.x - +b.x;
    });
}

And then use this reduce function:

reduceByMonth(data) {
    if (data) {
      return data.reduce((total, current, index) => {
        const month = { x: null, y: 0 };
        if (index !== 0 && (total && total[total.length - 1] && total[total.length - 1].x && monthsMatch(total[total.length - 1].x, current.x))) {
          total[total.length - 1].y = total[total.length - 1].y + current.y;
          return total;
        } else {
          month.x = new Date(current.x.getFullYear(), current.x.getMonth());
          month.y = month.y + current.y;
          total.push(month);
          return total;
        }
      }, []);
    } else {
      console.error('Cannot reduce undefined data');
      return []
    }
  }

the function monthsMatch is simply checking if the months of two dates match:

monthsMatch(dateA, dateB) {
    if (dateA.getFullYear() === dateB.getFullYear()) {
      return dateA.getMonth() === dateB.getMonth();
    } else {
      return false;
    }
}