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Learning Objectives ​

  • Understand how to Create, Read, Update & Delete elements of a list with the various Python methods & special syntax

Working with Lists (CRUD) ​

In order to build more complex applications, we need to understand how to perform the 4 main operations of handling data:

  • Create
  • Read
  • Update
  • Delete

Creating a List ​

A list can store multiple elements of different datatypes where all element are wrapped in a square bracket and separated by commas:

python
hobbies = ['basketball', 'badminton', 'cricket']

Reading a List ​

We can access different elements of list by using something similar to index numbers.

The first element of a list is given the index number of 0

The second element of a list is given the index number of 1 and so on...

The last element of a list is given the index number of (n - 1) where n stands for the number of element in the list

python
hobbies = ['basketball', 'badminton', 'cricket']
print(hobbies[0])
print(hobbies[1])

Output:

python
basketball
badminton

Updating a list ​

Methods:

Methods are built-in functions for a specific datatype!

They are used after the variable name followed by a . then the name of the method. (e.g. hobbies.insert() and hobbies.append())

Insert Method ​

We can also add additional elements to the list using the .insert() method after the variable name storing the list.

The .insert() method takes in two arguments: position (index number of where you want your data to be added) and element (data)

python
hobbies = ['basketball', 'badminton', 'cricket']
hobbies.insert(0, 'dancing')
print(hobbies)

Output:

python
['dancing', 'basketball', 'badminton', 'cricket']

Append Method ​

We can also add elements to the back of the list with the special .append() method as follows:

python
hobbies = ['basketball', 'badminton', 'cricket']
hobbies.append('dancing')
print(hobbies)

Output:

python
['basketball', 'badminton', 'cricket', 'dancing']

Deleting a list ​

There are two main ways to delete elements in a list, using either the .remove() or the .pop() method.

Remove Method ​

The .remove() method takes in one argument which is the value of what we want to delete.

python
hobbies = ['basketball', 'badminton', 'cricket']
hobbies.remove('basketball')
print(hobbies)

Output:

python
['badminton', 'cricket']

Pop Method ​

The .pop() method takes in one argument which is the index (number) of the element we want to delete:

python
hobbies = ['basketball', 'badminton', 'cricket']
hobbies.pop(1)
print(hobbies)

Output:

python
['basketball', 'cricket']

Pop Trick

If no argument is passed, .pop() will automatically remove the last element in the list