skip-the-front-of-an-array-with-drop.md

Skip The Front Of An Array With Drop

I've long been familiar with Ruby's Array#take which is a handy way to grab the first few elements of an array.

> [:a, :b, :c, :d, :e, :f, :g].take(4)
=> [:a, :b, :c, :d]

But what if I want to skip those first four elements of the array and get what remains. That is where Array#drop comes in.

> [:a, :b, :c, :d, :e, :f, :g].drop(4)
=> [:e, :f, :g]

How about a couple practical situations for use in a Rails app.

Here I want to segment out the first 6 books and whatever remains:

def index
  @books = Book.order(created_at: :desc).limit(10)

  @featured_books = @books.take(6)
  @remaining_books = @books.drop(6)
end

Or, what about cleaning up all but the first of these duplicate records:

Book
  .where(title: "The Murder of Roger Ackroyd")
  .drop(1)
  .each { |duplicate_book| duplicate_book.destroy }

The first record is ignored (dropped from the array) and the following records are processed by the #each where they get destroyed.