Let’s say that you have a Python list with the following 5 foods:
foods = ["pizza", "pasta", "steak", "chicken", "olives"]
How do we go about getting the last item?
Option 1
It’s actually really easy, you can select the index item by it’s total length minus one.
last_item = foods[len(foods)-1]
# "olives"
Option 2
Python has some really fantastic functionality around making your life easier. One of those such things is the ability to use slices.
You can return an item by it’s index if you know this, or you can return it’s value from the place within a list.
last_item = foods[-1]
# "olives
By stipulating an index of -1, we tell Python to return the last item; we can also return the second last item by using the index -2. This indexing technique is one of the many powerful features that make Python great for array operations like finding the intersection of two arrays
.
Additional safety checking
As with option2 above, this is a nice and simple way to achieve our objective, but what if the str() or list() object is empty? Understanding these edge cases is important when learning Python programming
.
List example
alist = []
# Generates an IndexError exception
alist[-1]
# Return an empty list
alist[-1:]
String example
astr = ''
# Generate an IndexError exception
astr[-1]
# Return an empty string
astr[-1:]
