Removing value from array if it is contained by another array

Question

I have two arrays

main_array = [[0,[1,4,5]], [1,[4,6,8]], [2,[5,6,7,8]], [3,[9,8]], [4,[7,2]]]
other_array = [[1,4,5],[9,8]]

What I want to do is to delete those elements in main_array if it can be found in other_array. (Meaning I will be left with [[1,[4,6,8]], [2,[5,6,7,8]],[4,[7,2]]] ) So I did the following:

other_array.each { |x|
for i in 0..main_array.length-1
  main_array.delete(x)
}

It didn't work. Any clues on how I should approach this?

Answer 1

main_array.reject { |_,a| other_array.include?(a) }
  #=> [[1,[4,6,8]], [2,[5,6,7,8]], [4,[7,2]]] 

Answer 2

You can use Enumerable#reject (this is a module that is included in almost all collections in Ruby, such as Arrays, Hashes, Sets and etc.), it returns new array with removed elements, based on some condition:

main_array.reject { |item| other_array.include? item[1] } 

Here item is every item in main_array. You can also "unwrap" your item if you want to control its elements individually:

main_array.reject { |(key, val)| other_array.include? val }

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