Subtracting one Array from another in Ruby

Question

I\'ve got two arrays of Tasks - created and assigned. I want to remove all assigned tasks from the array of created tasks. Here\'s my working, but messy, code:

Answer 1

You can subtract arrays in Ruby:

[1,2,3,4,5] - [1,3,4]  #=> [2,5]

ary - other_ary → new_ary Array Difference

Returns a new array that is a copy of the original array, removing any items that also appear in other_ary. The order is preserved from the original array.

It compares elements using their hash and eql? methods for efficiency.

[ 1, 1, 2, 2, 3, 3, 4, 5 ] - [ 1, 2, 4 ] #=> [ 3, 3, 5 ]

If you need set-like behavior, see the library class Set.

See the Array documentation.