Slicing of one-dimensional NumPy arrays works just like slicing of Python lists. We can select a piece of an array from index 3 to 7 that extracts the elements 3 through 6:

In: a = arange(9)
In: a[3:7]
Out: array([3, 4, 5, 6])

We can select elements from index 0 to 7 with a step of 2:

In: a[:7:2]
Out: array([0, 2, 4, 6])

Similarly as in Python, we can use negative indices and reverse the array:

In: a[::-1]
Out: array([8, 7, 6, 5, 4, 3, 2, 1, 0])