Filtering arrays

Often we want to operate only on elements of an array that fulfill a specific condition:

Select

Will return elements that match a specific condition

array = [1, 2, 3, 4, 5, 6]
array.select { |number| number > 3 } # => [4, 5, 6]

Reject

Will return elements that do not match a specific condition

array = [1, 2, 3, 4, 5, 6]
array.reject { |number| number > 3 } # => [1, 2, 3]

Both #select and #reject return an array, so they can be chained:

array = [1, 2, 3, 4, 5, 6]
array.select { |number| number > 3 }.reject { |number| number < 5 }
  # => [5, 6]