Lecture 3 : List & Tuple in Python | Python Full Course

Introduction

In this tutorial, we will explore lists and tuples in Python, two essential data structures that help you store and manipulate collections of data. Understanding these concepts is crucial for any Python programmer, as they form the foundation for more complex data handling. We'll cover their definitions, differences, methods, and practical examples to solidify your knowledge.

Step 1: Understanding Lists in Python

Lists are ordered collections that can hold items of different types. They are defined using square brackets.

How to Create a List

• Use square brackets to define a list.
• Items can be of various data types (e.g., integers, strings, etc.).

Example:

my_list = [1, 2, 3, "four", 5.0]

List Characteristics

• Lists are mutable, meaning you can change their content after creation.
• They maintain the order of elements.

Step 2: Difference Between Strings and Lists

While both strings and lists allow for storing sequences, they are fundamentally different.

Key Differences

• Type: Strings are immutable sequences of characters, while lists are mutable collections.
• Operations: You can perform different operations on strings and lists. For example, you can modify a list but not a string.

Step 3: List Slicing

List slicing allows you to access a portion of the list.

How to Slice a List

• Use the syntax list[start:stop:step].
• start is the index where slicing begins, stop is the index where it ends, and step defines the increment.

Example:

sliced_list = my_list[1:4]  # Returns [2, 3, "four"]

Step 4: List Methods

Python offers several built-in methods to manipulate lists.

Common List Methods

• append(): Adds an item to the end of the list.
• remove(): Removes the first occurrence of a value.
• pop(): Removes and returns an item at the given index.

Example:

my_list.append("six")
my_list.remove(3)
popped_value = my_list.pop(0)  # Removes and returns the first item

Step 5: Understanding Tuples in Python

Tuples are similar to lists but are immutable, meaning once created, they cannot be modified.

Creating a Tuple

• Tuples are defined using parentheses.

Example:

my_tuple = (1, 2, 3, "four", 5.0)

Step 6: Difference Between Tuples and Lists

Recognizing the differences is key to choosing the right data structure.

Key Differences

• Mutability: Lists are mutable; tuples are immutable.
• Performance: Tuples can be slightly faster than lists for iteration due to immutability.

Step 7: Tuple Slicing

Similar to lists, you can slice tuples.

How to Slice a Tuple

Use the same slicing syntax as with lists.

Example:

sliced_tuple = my_tuple[1:4]  # Returns (2, 3, "four")

Step 8: Tuple Methods

Tuples have fewer methods than lists due to their immutability.

Common Tuple Methods

• count(): Returns the number of times a value appears.
• index(): Returns the index of the first occurrence of a value.

Example:

count_of_two = my_tuple.count(2)  # Returns 1
index_of_four = my_tuple.index("four")  # Returns 3

Step 9: Practice Questions

To solidify your understanding, try the following practice questions:

1. Create a list with mixed data types and demonstrate at least three list methods.
2. Create a tuple and show how to slice it.
3. Compare the performance of a list and tuple in a simple iteration task.

Conclusion

Lists and tuples are foundational elements of Python programming. Lists are versatile and mutable, while tuples offer a fixed structure that can enhance performance in certain scenarios. Understanding when and how to use these data structures will greatly enhance your programming capabilities. As a next step, practice creating and manipulating lists and tuples in your own projects to reinforce what you've learned.