How can I sort list of map by map value in Elixir?

Question

I need to sort list of map, using value of map.

list = [
  %{id: 3, name: "Abe", count: 50},
  %{id: 1, name: "Bill", count: 10},
  %{id: 2, name: "Candy", count: 2},
]

For example, I need that list sorted by id:

list = [
  %{id: 1, name: "Bill", count: 10},
  %{id: 2, name: "Candy", count: 2},
  %{id: 3, name: "Abe", count: 50},
]

...or by count or name. How I can do it?

Answer 1

@IgodDrozdov provided a good solution. A more basic one: you can use Enum.sort/2:

Enum.sort(list, &(&1.id < &2.id))

2nd argument must define a binary relation (like sorter in Enum.sort_by/3)

Answer 2

There's Enum.sort_by function, which accepts list, mapper and sorter. The following code does the trick:

list = [
  %{id: 3, name: "Abe", count: 50},
  %{id: 1, name: "Bill", count: 10},
  %{id: 2, name: "Candy", count: 2},
]

Enum.sort_by list, &Map.fetch(&1, :id)

we need to provide list and a function which returns the attribute of mapping. Map.fetch(&1, :id) returns a value by key, or even simpler:

Enum.sort_by list, & &1.id

sorter by default is <=/2 function, which sorts the list in asc order.