Javascript array sorting based on multiple criteria (in one iteration)

Question

I have an array of cars:

enum Condition {
  New = 1,
  Used = 2
}

type Car = {
  make: string;
  model: string;
  age: number;
  condition: Condition;
};

const cars: Car[] = [
  {id: "1", make: "BMW", model: "E3", age: 12, condition: Condition.Used},
  {id: "2", make: "Audi", model: "A8", age: 4, condition: Condition.Used},
  {id: "3", make: "Mercedes", model: "SLK", age: 0, condition: Condition.New},
  {id: "4", make: "Ford", model: "CMAX", age: 3, condition: Condition.Used},
  {id: "5", make: "Ford", model: "BMAX", age: 0, condition: Condition.New},
  {id: "6", make: "Porsche", model: "Panamera", age: 0, condition: Condition.New},
]

And I have a search query:

const searchQuery: Car = {
  make: "Ford",
  model: "Panamera",
  age: 4,
  condition: Condition.New
}

I want to have a sorted array based on these rules:

items that exactly matches the make ("Ford") comes first
the rest that exactly matches the model ("Panamera") comes second
the rest that matches the condition of age = 4
the rest that is of condition New,
and at last any item that does not pass any of the tests

First what I did was to filter the array that matched the make and then the model then the age, etc... And then merged the resulting arrays to a final array (also filtered out duplicates that passed multiple criteria), but that require iterating over the cars as many times as the number of criteria I have. So I wondered if there is a better way to do it in one pass? Maybe using .sort somehow?

have u tried to use filter function smth like array.filter(item => item.make === query.make).filter(item => item.model === query.model) ........ and so on — Alopwer
– Alopwer, Commented May 17, 2020 at 19:38
or u can do it in 1 iteration array.filter(item => item.make === query.make && item.model === query.model) and so on — Alopwer
– Alopwer, Commented May 17, 2020 at 19:41
@Alopwer that's not what I want. that would just filter the cars to match all of the criteria at once, resulting an empty array, because there is no item that matches all conditions. — marchello
– marchello, Commented May 17, 2020 at 19:47

Shane · Accepted Answer · 2020-05-17 19:54:12Z

You can create a mapping function to determine your priority and just subtract the normalized value in your sort.

const Condition = { New: 1, Used: 2 };

const cars = [
  {id: "1", make: "BMW", model: "E3", age: 12, condition: Condition.Used},
  {id: "2", make: "Audi", model: "A8", age: 4, condition: Condition.Used},
  {id: "3", make: "Mercedes", model: "SLK", age: 0, condition: Condition.New},
  {id: "4", make: "Ford", model: "CMAX", age: 3, condition: Condition.Used},
  {id: "5", make: "Ford", model: "BMAX", age: 0, condition: Condition.New},
  {id: "6", make: "Porsche", model: "Panamera", age: 0, condition: Condition.New},
];

const searchQuery = {
  make: "Ford",
  model: "Panamera",
  age: 4,
  condition: Condition.New
};

const prioritize = (car, query) => {
  if (car.make === query.make) return 4;
  if (car.model === query.model) return 3;
  if (car.age === query.age) return 2;
  if (car.condition === query.condition) return 1;
  
  return 0;
};

const sorted = cars.sort((a, b) => {
  const prioA = prioritize(a, searchQuery);
  const prioB = prioritize(b, searchQuery);

  return prioB - prioA;
});

console.log(JSON.stringify(sorted, null, 2));

if you want the sort to work with multiple conditions, e.g. first make and model, you can add a simple recursive check and increment the priority:

const prioritize = (car, query) => {
  const { make, model, age, condition } = query;

  if (car.make === make) return 4 + prioritize(car, { model, age, condition });
  if (car.model === model) return 3 + prioritize(car, { age, condition });
  if (car.age === age) return 2 + prioritize(car, { condition });
  if (car.condition === condition) return 1;

  return 0;
};

in here, you just check the other query options next in line.

Nina Scholz · Accepted Answer · 2020-05-18 08:27:56Z

1

I suggest to use a different approach by checking the wanted first sorted condition first and then by the lower conditions.

This approach sorts ford with new condition first, instead of only ford first.

const
    Condition = { New: 1, Used: 2 },
    cars = [{ id: "1", make: "BMW", model: "E3", age: 12, condition: Condition.Used }, { id: "2", make: "Audi", model: "A8", age: 4, condition: Condition.Used }, { id: "3", make: "Mercedes", model: "SLK", age: 0, condition: Condition.New }, { id: "4", make: "Ford", model: "CMAX", age: 3, condition: Condition.Used }, { id: "5", make: "Ford", model: "BMAX", age: 0, condition: Condition.New }, { id: "6", make: "Porsche", model: "Panamera", age: 0, condition: Condition.New }],
    searchQuery = { make: "Ford", model: "Panamera", age: 4, condition: Condition.New };

cars.sort((a, b) => 
    (b.make === searchQuery.make) - (a.make === searchQuery.make) ||
    (b.model === searchQuery.model) - (a.model === searchQuery.model) ||
    (b.age === searchQuery.age) - (a.age === searchQuery.age) ||
    (b.condition === searchQuery.condition) - (a.condition === searchQuery.condition)
);

console.log(cars); // 5 4 6 2 3 1 instead of 4 5 6 1 2 3

.as-console-wrapper { max-height: 100% !important; top: 0; }

edited May 18, 2020 at 8:27

answered May 17, 2020 at 21:00

Nina Scholz

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1 Comment

marchello Over a year ago

interesting solution. if I understand correctly this solution is about making conditions "fall through" to later conditions when previous conditions matches, until there is a deciding one, correct? unfortunately, this is not my requirement, I have to do what the accepted solution does (even though yours makes more sense). anyway, thanks! (btw, the console logs 5 4 6 2 3 1 not 4 5 6 1 2 3)

xdeepakv · Accepted Answer · 2020-05-17 20:00:45Z

It can be considered as priority sort. Give different priorities(points) and calculate total points.

JS Version

var Condition;
(function (Condition) {
  Condition[(Condition["New"] = 1)] = "New";
  Condition[(Condition["Used"] = 2)] = "Used";
})(Condition || (Condition = {}));

const priority = {
  make: 5,
  model: 4,
  age: 3,
  condition: 2,
};
const calculatePoint = (obj, params) =>
  Object.entries(obj).reduce((p, [key, value]) => {
    if (value === params[key]) p += priority[key];
    return p;
  }, 0);
const sortData = (data, params) =>
  data.sort((x, y) => calculatePoint(y, params) - calculatePoint(x, params));

const cars = [{"id":"1","make":"BMW","model":"E3","age":12,"condition":2},{"id":"2","make":"Audi","model":"A8","age":4,"condition":2},{"id":"3","make":"Mercedes","model":"SLK","age":0,"condition":1},{"id":"4","make":"Ford","model":"CMAX","age":3,"condition":2},{"id":"5","make":"Ford","model":"BMAX","age":0,"condition":1},{"id":"6","make":"Porsche","model":"Panamera","age":0,"condition":1}]
const searchQuery = {
  make: "Ford",
  model: "Panamera",
  age: 4,
  condition: Condition.New,
};
console.log(sortData(cars, searchQuery));

TS version

enum Condition {
  New = 1,
  Used = 2,
}

type Car = {
  id?: string;
  make: string;
  model: string;
  age: number;
  condition: Condition;
};

const cars: Car[] = [{"id":"1","make":"BMW","model":"E3","age":12,"condition":2},{"id":"2","make":"Audi","model":"A8","age":4,"condition":2},{"id":"3","make":"Mercedes","model":"SLK","age":0,"condition":1},{"id":"4","make":"Ford","model":"CMAX","age":3,"condition":2},{"id":"5","make":"Ford","model":"BMAX","age":0,"condition":1},{"id":"6","make":"Porsche","model":"Panamera","age":0,"condition":1}]
;
const searchQuery: Car = {
  make: "Ford",
  model: "Panamera",
  age: 4,
  condition: Condition.New,
};

const priority = {
  make: 5,
  model: 4,
  age: 3,
  condition: 2,
};
const calculatePoint = (obj: Car, params: Car) =>
  Object.entries(obj).reduce((p: number, [key, value]) => {
    if (value === params[key]) p += priority[key];
    return p;
  }, 0);
const sortData = (data: Car[], params: Car) =>
  data.sort(
    (x: Car, y: Car) => calculatePoint(y, params) - calculatePoint(x, params)
  );
console.log(sortData(cars, searchQuery));

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