each-Select

While Ruby’s  each  method is useful, it also comes with an awesome extended family of methods that are even more powerful!
For the next few examples, we’ll work with a slightly more complex data structure. It look like this:

friends = [
  {
    name: "Diego",
    status: "Online"
  },
  {
    name: "Liam",
    status: "Away"
  },
  {
    name: "Gloria",
    status: "Online"
  },
  {
    name: "Charlie",
    status: "Away"
  }
]

select  is similar to  each  in that we pass it a block to run on each element in the collection, but the similarities stop there. The important difference is that  select  will return a new collection with only the items that the block returned  true  for. It sounds pretty intimidating at first, so let’s walk through an example.
We can use  select  to create a new Array filled with only our online friends:

online_friends = friends.select do |friend|
  friend[:status] == "Online"
end

Because the block is so short, it would also work well as a one-liner:

online_friends = friends.select{|friend| friend[:status] == "Online"}

select  will go through each element one at a time, starting with  {name: “Diego”, status: “Online”} , passing it to the block we wrote. The block contains a single line:  friend[:status] == “Online” . That line returns either  true  or  false . If the block returns  true , that specific item is added to a new Array that will be returned at the very end of  select .
This table shows each step of the process:
 
 
At the very end,  select  returns this Array which we save to a new  online_friends  variable:

[{ name: "Diego", status: "Online"}, { name: "Gloria", status: "Online"}]