To cast a numpy array from bool to int, should I multiply by one or use astype(int)?

Question

bool_array * 1 and bool_array.astype(int) appear to do the same thing. Which is more efficient?

Answer 1

bool_array.astype(int) is faster ( Colab notebook ):

import numpy as np

bool_array = np.random.choice([0, 1], size=1_000_000).astype(bool)

%timeit int_array = bool_array * 1

1000 loops, best of 5: 1.5 ms per loop

%timeit int_array = bool_array.astype("int")

1000 loops, best of 5: 973 µs per loop