python how slicing work code example

Example 1: python array index range

a[start:stop]  # items start through stop-1
a[start:]      # items start through the rest of the array
a[:stop]       # items from the beginning through stop-1
a[:]           # a copy of the whole array

Example 2: is : and :: the same in python slice

a[-1]    # last item in the array
a[-2:]   # last two items in the array
a[:-2]   # everything except the last two items