How to delete last n rows from Numpy array?

Question

I'm trying to delete the last few rows from a numpy array. I'm able to delete 0 to i rows with the following code.

for i, line in enumerate(two_d_array1):
    if all(v == 0 for v in line):
        pass
    else:
        break

two_d_array2 = np.delete(two_d_array1, slice(0, i), axis=0)

Any suggestions on how to do the same for the end of the array?

for i, line in enumerate(reversed(two_d_array2)):
    if all(v == 0 for v in line):
        pass
    else:
        break

two_d_array3 = np.delete(two_d_array2, **slice(0, i)**, axis=0)

Answer 1

You can use slice notation for your indexing.

To remove the last n rows from an array:

a = np.array(range(10)).reshape(5, 2)
>>> a
array([[0, 1],
       [2, 3],
       [4, 5],
       [6, 7],
       [8, 9]])

n = 2  # Remove last two rows of array.
>>> a[:-n, :]
array([[0, 1],
       [2, 3],
       [4, 5]])

To remove the first n rows from an array:

>>> a[n:, :]  # Remove first two rows.
array([[4, 5],
       [6, 7],
       [8, 9]])