Remove duplicates in a JavaScript object array and sum the entries

Question

I have an object with two properties: x and y, of types String and number respectively.

The corresponding (x,y) values are used to plot a time series using Plotly in an Express.js application, with x taking the format 2013-10-04T22:23.

Now say I have an object with duplicate x values, and I need to remove the duplicates, leaving only one entry for that x value and sum up the corresponding y values, again leaving only one corresponding y value.

For example:

var data = [
               {
                   x: ["2013-10-04 22:22", "2013-10-04 22:22", "2013-10-04 22:22", 
                       "2013-12-12 15:15"],
                   y: [1, 1, 1, 6]
               }
           ];

I want to sum up the y values for the 2013-10-04 22:22 x values, leaving only one x value y value pair like so:

data = [
           {
               x: ["2013-10-04 22:22", 
                   "2013-12-12 15:15"],
               y: [3, 6]
           }
       ];

How would one do this?

soltex · Accepted Answer · 2020-07-17 13:22:27Z

2

You can create a function that receives an object and manipulate the object the way you want:

const obj = {
  x: ["2013-10-04 22:22", "2013-10-04 22:22", "2013-10-04 22:22", "2013-12-12 15:15"],
  y: [1, 1, 1, 6]
}

function removeObjDuplicates ({ x, y }) {

  const occurrences = {};

  for (let i = 0; i < x.length; i++) {
      occurrences[x[i]] = (occurrences[x[i]] || 0) + y[i];
  }

  return {
    x:  Object.keys(occurrences),
    y:  Object.values(occurrences),
  }
}

removeObjDuplicates(obj) will return:

{
   x: ["2013-10-04 22:22", "2013-12-12 15:15"],
   y: [3, 6]
}

edited Jul 17, 2020 at 13:22

answered Jul 17, 2020 at 13:12

soltex

3,6111 gold badge25 silver badges36 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

abarc Over a year ago

Thank you, this is what I was looking for.

Collectives™ on Stack Overflow

Remove duplicates in a JavaScript object array and sum the entries

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related