Group data in array by attribute

Question

What I want to have is nested data grouped by the day number.

This is an example of a array that I want to group. I am using the lodash plugin.

[{
  "Pnl": 29.0035635,
  "date": "11/14/2022",
  "dayNumber": 1,
  "translationDayOfWeek": "Monday"
},
{
  "Pnl": 50.8878545,
  "date": "11/08/2022",
  "dayNumber": 2,
  "translationDayOfWeek": "Tuesday"
},
{
  "Pnl": 73.1014552,
  "date": "11/08/2022",
  "dayNumber": 2,
  "translationDayOfWeek": "Tuesday"
},
{
  "Pnl": 32.477,
  "date": "11/08/2022",
  "dayNumber": 6,
  "translationDayOfWeek": "Saturday"
},
{
  "Pnl": 25.43999561,
  "date": "09/30/2022",
  "dayNumber": 5,
  "translationDayOfWeek": "Friday"
},
{
  "Pnl": 17.6294068,
  "date": "09/30/2022",
  "dayNumber": 1,
  "translationDayOfWeek": "Monday"
}]

This is want I want for a output:

[
  {
    "dayNumber": 1,
    "orders": [
      {
        "Pnl": 29.0035635,
        "date": "11/14/2022",
        "dayNumber": 1,
        "translationDayOfWeek": "Monday"
      },
      {
        "Pnl": 17.6294068,
        "date": "09/30/2022",
        "dayNumber": 1,
        "translationDayOfWeek": "Monday"
      }
    ]
  },
  {
    "dayNumber": 2,
    "orders": [
      {
        "Pnl": 50.8878545,
        "date": "11/08/2022",
        "dayNumber": 2,
        "translationDayOfWeek": "Tuesday"
      },
      {
        "Pnl": 73.1014552,
        "date": "11/08/2022",
        "dayNumber": 2,
        "translationDayOfWeek": "Tuesday"
      }
    ]
  }
]

I tried the solutions on stackoverflow post but it's not the result I need.

weeknumber isn't in the data, and if the result ends up with a different structure, like with orders, then it isn't just a sort. — danh
– danh, Commented Nov 24, 2022 at 1:25
You are looking for group, not sort. See stackoverflow.com/questions/70844485/…, that is not the same as you need, but some concept is the same — Manuel Romeiro
– Manuel Romeiro, Commented Nov 24, 2022 at 1:34
Please edit your post because the output you're showing is not a differently sorted version of the input. It's a complete rewrite, so in more detail explain what part of the rewriting process is a problem. Also, don't just link to another post and go "this didn't work", explain what from that post you did, what you expected it to do, and how what it actually did differed and what debugging you already did because all those things change what an answer should look like. — Mike 'Pomax' Kamermans
– Mike 'Pomax' Kamermans, Commented Nov 24, 2022 at 1:35
@Mike'Pomax'Kamermans Yes, I should put a better description on my post. I am new here on StackOverflow but thanks for the recommendation. — ChahinDev
– ChahinDev, Commented Nov 24, 2022 at 1:40

subodhkalika · Accepted Answer · 2022-11-24 01:40:29Z

2

If you are using loadsh,

const arr = []; //your array
_.map(
    _.groupBy(arr, function (obj) {return obj.dayNumber}),
    (order,index) => ({dayNumber: index, orders: order})
)

answered Nov 24, 2022 at 1:40

subodhkalika

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Comments

danh · Accepted Answer · 2022-11-24 01:36:09Z

0

The snippet below does grouping (which is what it looks like the OP wants) using reduce().

let data = [{
  "Pnl": 29.0035635,
  "date": "11/14/2022",
  "dayNumber": 1,
  "translationDayOfWeek": "Monday"
},
{
  "Pnl": 50.8878545,
  "date": "11/08/2022",
  "dayNumber": 2,
  "translationDayOfWeek": "Tuesday"
},
{
  "Pnl": 73.1014552,
  "date": "11/08/2022",
  "dayNumber": 2,
  "translationDayOfWeek": "Tuesday"
},
{
  "Pnl": 32.477,
  "date": "11/08/2022",
  "dayNumber": 6,
  "translationDayOfWeek": "Saturday"
},
{
  "Pnl": 25.43999561,
  "date": "09/30/2022",
  "dayNumber": 5,
  "translationDayOfWeek": "Friday"
},
{
  "Pnl": 17.6294068,
  "date": "09/30/2022",
  "dayNumber": 1,
  "translationDayOfWeek": "Monday"
}];

let grouped = data.reduce((acc, el) => {
  let dayNumber = el.dayNumber;
  acc[dayNumber] ??= { dayNumber, orders: [] };
  acc[dayNumber].orders.push(el);
  return acc;
}, {});
grouped = Object.values(grouped).sort((a,b) => a.dayNumber-b.dayNumber);

console.log(grouped)

It's possible that the OP also wants the orders array sorted somehow. But I can't discern how. To do that, iterate the result and do the sort, something like the following:

grouped.forEach(group => group.orders.sort((a,b) => {
  /* sort based on some prop the OP hasn't defined */
});

answered Nov 24, 2022 at 1:36

danh

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3 Comments

ChahinDev Over a year ago

This code worked out for me. Thanks. I have a question about row 358. What is the '??=' doing in this code? Is this a typescript operator?

MauricioRobayo Over a year ago

did you google it? developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…

danh Over a year ago

It's a thing called a "nullish coalescing assignment. The gist is it will only assign if the left side is null or undefined. developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…

Shakya Peiris · Accepted Answer · 2022-11-24 01:37:29Z

Try this one

const arr = [{
  "Pnl": 29.0035635,
  "date": "11/14/2022",
  "dayNumber": 1,
  "translationDayOfWeek": "Monday"
},
{
  "Pnl": 50.8878545,
  "date": "11/08/2022",
  "dayNumber": 2,
  "translationDayOfWeek": "Tuesday"
},
{
  "Pnl": 73.1014552,
  "date": "11/08/2022",
  "dayNumber": 2,
  "translationDayOfWeek": "Tuesday"
},
{
  "Pnl": 32.477,
  "date": "11/08/2022",
  "dayNumber": 6,
  "translationDayOfWeek": "Saturday"
},
{
  "Pnl": 25.43999561,
  "date": "09/30/2022",
  "dayNumber": 5,
  "translationDayOfWeek": "Friday"
},
{
  "Pnl": 17.6294068,
  "date": "09/30/2022",
  "dayNumber": 1,
  "translationDayOfWeek": "Monday"
}];
const newArr = [];

arr.forEach((i) => {
    if (newArr.find(j => j.dayNumber === i.dayNumber)){
        const index = newArr.findIndex(j => j.dayNumber === i.dayNumber)
        newArr[index].orders.push(i);
    }
    else {
        newArr.push({
            dayNumber: i.dayNumber,
            orders: [i]
        })
    }
})

newArr.sort((a, b) => parseInt(a.dayNumber) - parseInt(b.dayNumber))

console.log(newArr)

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