[Tut] How to Get the Last Element of a Python List?

[xSicKxBot]

How to Get the Last Element of a Python List?

Problem: Given a list. How to access the last element of this list?

Example: You have the list

Code:

['Alice', 'Bob', 'Liz']

and you want to get the last element

Code:

'Liz'

.

Quick solution: Use negative indexing-1.

Code:

friends = ['Alice', 'Bob', 'Liz'] print(friends[-1]) # Liz

To access the last element of a Python list, use the indexing notation

Code:

list[-1]

with negative index

Code:

-1

which points to the last list element. To access the second-, third-, and fourth-last elements, use the indices

Code:

-2

,

Code:

-3

, and

Code:

-4

. To access the

Code:

n

last elements of a list, use slicing

Code:

list[:-n-1:-1]

with negative stop index

Code:

-n

and negative step size

Code:

-1

.

Method 1: Access the Last Element with Negative Indexing -1

To bring everybody on the same page, let me quickly explain indices in Python by example. Suppose, you have list

Code:

['u', 'n', 'i', 'v', 'e', 'r', 's', 'e']

. The indices are simply the positions of the characters of this string.

(Positive) Index |
0 |
1 |
2 |
3 |
4 |
5 |
6 |
7

Element |
‘u’ |
‘n’ |
‘i’ |
‘v’ |
‘e’ |
‘r’ |
‘s’ |
‘e’

Negative Index |
-8 |
-7 |
-6 |
-5 |
-4 |
-3 |
-2 |
-1

Positive Index: The first character has index , the second character has index

Code:

1

, and the

Code:

i

-th character has index

Code:

i-1

.

Negative Index: The last character has index

Code:

-1

, the second last character has index

Code:

-2

, and the

Code:

i

-th last character has index

Code:

-i

.

Now, you can understand how to access the last element of the list:

Code:

friends = ['Alice', 'Bob', 'Liz'] print(friends[-1]) # Liz

But how to access the second-last element? Just use index -2!

Code:

friends = ['Alice', 'Bob', 'Liz'] print(friends[-2]) # Bob

Method 2: Access the n Last Elements with Slicing

But what if you want to access the

Code:

n

last elements? The answer is slicing.



The default slicing operation

Code:

list[start:stop:step]

accesses all elements between

Code:

start

(included) and

Code:

stop

(excluded) indices, using the given

Code:

step

size over the list. For example, the slicing operation

Code:

friends[0:3:2]

would start with the first element

Code:

'Alice'

and end with the third element

Code:

'Liz'

(included), but taking only every second element due to the step size of

Code:

2

—effectively skipping the second element

Code:

'Bob'

.

You can use slicing with negative

Code:

start

and

Code:

stop

indices and with negative stop size to slice from the right to the left. To access the

Code:

n

last elements in the slice, you’d therefore use the following code:

Code:

universe = ['u', 'n', 'i', 'v', 'e', 'r', 's', 'e'] # Access the n=4 last element from the list: n = 4 print(universe[:-n-1:-1]) # ['e', 's', 'r', 'e']

There are different points to consider in the code:

• You use a negative step size -1 which means that you slice from the right to the left.
  
  
• If you don’t provide a value for
  Code:

  start
  ,
  Code:

  stop
  , or
  Code:

  step
  indices, Python takes the default ones. For example, we don’t provide the
  Code:

  start
  index and perform negative slicing so Python starts from the last element
  Code:

  'e'
  .
  
  
• You want to get the
  Code:

  n
  last elements. The
  Code:

  n
  -th last element has index
  Code:

  -n
  . But as the stop index is never included in the slice, we need to slice one step further to the left—to the element with index
  Code:

  -n-1
  to include the element with index
  Code:

  -n
  .
  

Try this yourself in our interactive code shell:

https://repl.it/@finxter/FailingVagueAgents?lite=true

Exercise: What happens if the list has less than n characters?

Where to Go From Here?

Enough theory, let’s get some practice!

To become successful in coding, you need to get out there and solve real problems for real people. That’s how you can become a six-figure earner easily. And that’s how you polish the skills you really need in practice. After all, what’s the use of learning theory that nobody ever needs?

Practice projects is how you sharpen your saw in coding!

Do you want to become a code master by focusing on practical code projects that actually earn you money and solve problems for people?

Then become a Python freelance developer! It’s the best way of approaching the task of improving your Python skills—even if you are a complete beginner.

Join my free webinar “How to Build Your High-Income Skill Python” and watch how I grew my coding business online and how you can, too—from the comfort of your own home.

Join the free webinar now!

The post How to Get the Last Element of a Python List? first appeared on Finxter.