Adding my 2 cents to the wonderful answer posted by @Mike O'Connor the below code is just another adaptation of the same using the bitwise inverse.

A = np.array([1, 2, 23, 4, 15, 78, 6, 7, 18, 9, 10]) 
~np.sort(~A)

Output: [78 23 18 15 10 9 7 6 4 2 1]