TypeError: slice indices must be integers or None or have an __index__ method (Python)

Question

I want to select some of the elements of a list using the following code:

random_indices = np.random.permutation(len(Y))[:how_many_to_select]

But I am getting the error: TypeError: slice indices must be integers or None or have an __index__ method

Answer 1

Your variable 'how_many_to_select' is not an integer. If it's a float, change its type to int and then you will not get the error. You can try one of the following approaches:

Approach 1

random_indices = np.random.permutation(len(Y))[:int(how_many_to_select)]

Approach 2

how_many_to_select = int(how_many_to_select)

random_indices = np.random.permutation(len(Y))[:how_many_to_select]