Sort grouped array in asc/desc order-CodePudding

Can anyone assist in sorting the below array in ascending / descending order? The array is to be sorted based on the highest number in each grouping (grouped using brand). Numbers in each group are to be sorted as well:

original_array = [
  { brand: "Ford",   number: "1", },
  { brand: "BMW",    number: "1", },
  { brand: "BMW",    number: "5", },
  { brand: "BMW",    number: "20",},
  { brand: "Toyota", number: "10",}
];

desc_order = [
  { brand: "BMW",    number: "20",},
  { brand: "BMW",    number: "5", },
  { brand: "BMW",    number: "1", },
  { brand: "Toyota", number: "10",},
  { brand: "Ford",   number: "1", }
];

asc_order = [
  { brand: "Ford",   number: "1", },
  { brand: "Toyota", number: "10",},
  { brand: "BMW",    number: "1", },
  { brand: "BMW",    number: "5", },
  { brand: "BMW",    number: "20",}
];

CodePudding user response：

Since the order of the brands in the output depends on maximum values in their group, I would suggest to first create an object that lists the maximum number per brand.

Then use that to sort by, using the following sequence of ordering:

First by the maximum value for the brand
When that is equal, by the name of the brand (since several brands could have the same maximum number)
When that is equal, by the number itself

Implementation:

const array = [ { brand: "Ford", number: "1", }, { brand: "BMW", number: "1", }, { brand: "BMW", number: "5", }, { brand: "BMW", number: "20", }, { brand: "Toyota", number: "10", } ];

// First collect the maximum values per brand as an aggregate:
const aggr = {};
for (let {brand, number} of array) { 
    aggr[brand] = Math.max(number, aggr[brand] ?? number);
}

// Ascending
array.sort((a, b) => aggr[a.brand] - aggr[b.brand] 
                  || a.brand.localeCompare(b.brand)
                  || a.number - b.number);
console.log(array);

// Descending
array.sort((a, b) => aggr[b.brand] - aggr[a.brand]
                  || b.brand.localeCompare(a.brand)
                  || b.number - a.number);
console.log(array);