How to sort one array based on another array using Ruby

Question

There are two arrays:

A = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] 
B = [3, 4, 1, 5, 2, 6]

I want to sort B in a way that for all the elements of B that exists in A, sort the elements in the order that is in array A.

The desired sorted resulted would be

B #=> [1, 2, 3, 4, 5, 6]

I have tried to do

B = B.sort_by { |x| A.index }

but it does not work.

This question differs from the possible duplicates because it deals with presence of elements in the corresponding array and no hashes are present here.

Answer 1

It perfectly works:

▶ A = [1,3,2,6,4,5,7,8,9,10]
▶ B = [3,4,1,5,2,6]
▶ B.sort_by &A.method(:index)
#⇒ [1, 3, 2, 6, 4, 5]

If there could be elements in B that are not present in A, use this:

▶ B.sort_by { |e| A.index(e) || Float::INFINITY }

Answer 2

I would start by checking what elements from B exist in A :

B & A

and then sort it:

(B & A).sort_by { |e| A.index(e) }