TypeScript: Sort Array 1 by indexOf value from Array 2

Question

I'm new to Typescript/JavaScript so I'm sure I'm missing something easy.

I have an array of 2 types, each of which has a sub-array of 3 - 4 names:

myArray = [
{
    "type": "abc",
    "names": {
        "Jane Smith": 5,
        "John Doe": 3,
        "Jack Jones": 2
    }
},
{
    "type": "xyz",
    "names": {
        "Jane Smith": 3,
        "John Doe": 7,
        "Jack Jones": 3
    }
}
];

I need to know which main type has the highest overall total and show that first. In this example "xyz" has the highest total ((3 + 7 + 3) vs. (5 + 3 + 2)). So I'd want to display xyz before abc.

I am successfully getting the totals of the two and putting them into a new array called totalValues:

totalValues = [
{
    "type": "xyz",
    "count": 13            
    }
},
{
    "type": "abc",    
    "count": 10            
    }
}
];

The problem is that I need to sort my original array (myArray) by type based on the total and I can't figure it out.

let sortedTotalValues = totalValues.sort().reverse();    //highest value first

let sortedGroupNames = null;

sortedGroupNames = myArray.sort((a, b) => {            
    return sortedTotalValues[0].indexOf(a) - sortedTotalValues[0].indexOf(b);
});

Any help would be much appreciated.

Damian Green · Accepted Answer · 2020-01-21 21:28:35Z

1

const myArray = [
{
    "type": "abc",
    "names": {
        "Jane Smith": 5,
        "John Doe": 3,
        "Jack Jones": 2
    }
},
{
    "type": "xyz",
    "names": {
        "Jane Smith": 3,
        "John Doe": 7,
        "Jack Jones": 3
    }
}
];
const sum =   (accumulator, currentValue) => accumulator + currentValue;

const total = x=>Object.values(x.names).reduce(sum)

console.log(myArray.sort((a,b)=>(total(b)-total(a))))
[Codepen here][1]


  [1]: https://codepen.io/drGreen/pen/eYmbeze

answered Jan 21, 2020 at 21:28

Damian Green

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Comments

Gangadhar Gandi · Accepted Answer · 2020-01-21 21:22:51Z

1

Try this,

let myArray = [
  {
    "type": "abc",
    "names": {
       "Jane Smith": 5,
       "John Doe": 3,
       "Jack Jones": 2
    }
  },
  {
    "type": "xyz",
    "names": {
       "Jane Smith": 3,
       "John Doe": 7,
       "Jack Jones": 3
    }
  }
];

let modifiedArray = myArray.map(obj => {
  let total = 0;
  for (var property in obj.names) {
    total += obj.names[property];
  }
  return {
    ...obj,
    totalNamesValue: total // Added totalNamesValue which stores the total
  }
});

let sortedArray = modifiedArray.sort((a, b) => b.totalNamesValue - a.totalNamesValue)

console.log(sortedArray);

answered Jan 21, 2020 at 21:22

Gangadhar Gandi

2,26214 silver badges20 bronze badges

Comments

norbitrial · Accepted Answer · 2020-01-21 21:28:07Z

I guess if you try to find first the index of the element based on the type property with findIndex() then you can push it into the right place in the final array.

Maybe you can try with the following:

const myArray = [{"type":"abc","names":{"Jane Smith":5,"John Doe":3,"Jack Jones":2}},{"type":"xyz","names":{"Jane Smith":3,"John Doe":7,"Jack Jones":3}}];

const countsInOrder = myArray.map(({type, names}) => ({
  type,
  count: Object.entries(names).reduce((a, [k,v]) => a + v, 0)
})).sort((a,b) => b.count - a.count);

const result = new Array(myArray.length);

myArray.forEach(e => {
  const index = countsInOrder.findIndex(a => a.type === e.type);
  result[index] = e;
});

console.log(result);

I hope that helps!

lidlbobbytables · Accepted Answer · 2020-01-22 15:09:57Z

Given an array and a sorting criteria you can simply feed in your criteria into the .sort(...) method as a function.

myArray = [
{
    "type": "abc",
    "names": {
        "Jane Smith": 5,
        "John Doe": 3,
        "Jack Jones": 2
    }
},
{
    "type": "xyz",
    "names": {
        "Jane Smith": 3,
        "John Doe": 7,
        "Jack Jones": 3
    }
}
];

myArray.sort((a,b) => {
  let sumA = Object.values(a["names"]).reduce((total, curr) => total + curr, 0);
  let sumB = Object.values(b["names"]).reduce((total, curr) => total + curr, 0);
  
  return sumB -sumA;
});

console.log(myArray);

Note: This does have the overhead of recalculating the sum everytime it makes a comparision this can be improved by simply substituting the sumA and sumB variables to get the value from a precomputed array shown below

myArray = [
{
    "type": "abc",
    "names": {
        "Jane Smith": 5,
        "John Doe": 3,
        "Jack Jones": 2
    }
},
{
    "type": "xyz",
    "names": {
        "Jane Smith": 3,
        "John Doe": 7,
        "Jack Jones": 3
    }
}
];

let total = myArray.map( el => 
  Object.values(el["names"]).reduce((total, curr) => total + curr, 0));
  


myArray.sort((a,b) => {
  let sumA = total[myArray.findIndex( el => el["type"] === a["type"] )];
  let sumB = total[myArray.findIndex( el => el["type"] === b["type"] )];
  
  return sumB - sumA;
});

console.log(myArray);

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