Question

I have an array of objects that I want to count and transform. For instance:

[#<User id:1, count:0>, #<User id:2, count:0>, #<User id:2, count:0>, #<User id:3, count:0>, #<User id:1, count:0>, #<User id:1, count:0>]

would become:

[#<User id:1, count:3>, #<User id:2, count:2>, #<User id:3, count:1>]

The transformation is what confuses me, since a ‘map’, goes straight through, but this would be recursive.

Answer 1

[user1, user2, user2, user3, user1, user1].group_by(&:id).map do |id, users|
  users.first.count = users.size
  users.first
end