Group And Sum Datetime Object By Date In Javascript

What is the best way to group objects by date and add them all up to create a single JavaScript object? I prefer code readability and lesser lines of code over performance as the a

Solution 1:

• Iterate your array of objects ($.each() function can be used to iterate over any collection.)
• Convert UTC format date string to ISO format using toISOString() method.
• Maintain common array for date so that you can easily map your repeated date location using indexOf() method.

Here is the Code:

var arr = [
  {"Timestamp":"Thu, 01 Jan 2015 00:57:00 GMT","cp":2,"pc":2},
  {"Timestamp":"Thu, 01 Jan 2015 01:57:00 GMT","cp":0,"pc":4},
  {"Timestamp":"Thu, 01 Jan 2015 02:57:00 GMT","cp":2,"pc":2},
  {"Timestamp":"Thu, 01 Jan 2015 03:57:00 GMT","cp":0,"pc":4},

  {"Timestamp":"Thu, 02 Jan 2015 00:57:00 GMT","cp":2,"pc":2},
  {"Timestamp":"Thu, 02 Jan 2015 01:57:00 GMT","cp":0,"pc":4},
  {"Timestamp":"Thu, 02 Jan 2015 02:57:00 GMT","cp":2,"pc":2},
  {"Timestamp":"Thu, 02 Jan 2015 03:57:00 GMT","cp":0,"pc":4}
];
var resultArr = [];
var dateArr = [];   

$.each(arr, function () {
// Easiest way to get your required date formatvar date = newDate(this.Timestamp).toISOString().replace(/T/, ' ').split(' ')[0];
   var index = dateArr.indexOf(date);
   if (index == -1) {
       dateArr.push(date);
       var obj = {Date: date, cp: this.cp, pc: this.pc};
       resultArr.push(obj);
   } 
   else {
       resultArr[index].cp += this.cp;
       resultArr[index].pc += this.pc;
   }
});
console.log(resultArr); // [ {"Date":"2015-01-01", "cp":4, "pc":12}, {"Date":"2015-01-02", "cp":4, "pc"12} ]

Hope this may helpful for you.

Solution 2:

Try this.

var timeArray=[
    {"Timestamp":"Thu, 01 Jan 2015 00:57:00 GMT","cp":2,"pc":2},
    {"Timestamp":"Thu, 01 Jan 2015 01:57:00 GMT","cp":0,"pc":4},
    {"Timestamp":"Thu, 01 Jan 2015 02:57:00 GMT","cp":2,"pc":2},
    {"Timestamp":"Thu, 01 Jan 2015 03:57:00 GMT","cp":0,"pc":4},

    {"Timestamp":"Thu, 02 Jan 2015 00:57:00 GMT","cp":2,"pc":2},
    {"Timestamp":"Thu, 02 Jan 2015 01:57:00 GMT","cp":0,"pc":4},
    {"Timestamp":"Thu, 02 Jan 2015 02:57:00 GMT","cp":2,"pc":2},
    {"Timestamp":"Thu, 02 Jan 2015 03:57:00 GMT","cp":0,"pc":4}
]

varobject = {}, resultArray = [];

for (var i = 0; i < timeArray.length; i++) {
    var date = timeArray[i].Timestamp;
    var localDateString = newDate(date).getFullYear() + '-' + (newDate(date).getMonth() + 1) + '-' + newDate(date).getDate();
    if (object[localDateString]) {
        object[localDateString].cp += timeArray[i].cp;
        object[localDateString].pc += timeArray[i].pc;
    } else {
        timeArray[i].Date = localDateString;
        delete timeArray[i].Timestamp;
        object[localDateString] = timeArray[i];
    }
}

for (var prop inobject)
    resultArray.push(object[prop]);

console.log(resultArray);

Solution 3:

I believe a simple utility library such as Underscore.js or Lodash could do the job, however, this looks like a task plain old vanilla Javascript can take on by itself.

Check out the Array.prototype.map function, or probably better yet an Array.prototype.sort that takes in a sorting function applying logic to a given object's .Timestamp property.

Edit: something like

yourArray.sort(function(objA, objB){
  return objA.Timestamp > objB.TimeStamp ? -1 : 1;
});

may work.

EDIT: I see now you are trying to merge dates. In that case, I would say Array.prototype.map chained with Array.prototype.reduce is a possible path to go down. You could also (messily) use Array.prototype.filter to push all arrays of a given date into a single array, and so on for each date.

Edit:

How about a reduce, then?

var thingYouWant = yourArray.reduce(function(summed, current){
    date = changeIntoOnlyDayDate(current.Timestamp);
    var found = false;
    summed.forEach(function(obj){
        if(obj.Timestamp === date){ obj.cp++; found = true;};
    }
    if(!found){summed.push(turnThisDateIntoDesiredObject(date))}

    }
    return summed;
    }, []);