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*

+2 votes

Best answer

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]