Python - Alternative for using numpy array as key in dictionary

If you want to quickly store a numpy.ndarray as a key in a dictionary, a fast option is to use ndarray.tobytes() which will return a raw python bytes string which is immutable

my_array = numpy.arange(4).reshape((2,2))
my_dict = {}
my_dict[my_array.tobytes()] = None

After done some researches and reading through all comments. I think I've known the answer to my own question so I'd just write them down.

1. Write a class to contain the data in the array and then override __hash__ function to amend the way how it is hashed as mentioned by ZdaR
2. Convert this array to a tuple, which makes the list hashable instantaneously.Thanks to hpaulj

I'd prefer method No.2 because it fits my need better, as well as simpler. However, using a class might bring some additional benefits so it could also be useful.