Filtering a list based on a list of booleans

Question

I have a list of values which I need to filter given the values in a list of booleans:

list_a = [1, 2, 4, 6]
filter = [True, False, True, False]

Answer 1

To do this using numpy, ie, if you have an array, a, instead of list_a:

a = np.array([1, 2, 4, 6])
my_filter = np.array([True, False, True, False], dtype=bool)
a[my_filter]
> array([1, 4])