Python Programming Lecture: Lists

Jul 10, 2024

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Python Programming Lecture: Lists

Previous Video Recap

  • Explored control statements:
    • Simple if
    • Nested if
    • If-else
    • Elif
  • Completed a coding exercise on creating a log calculator

New Concept: Python Lists

What is a List?

  • A list is a data structure used to store multiple items in a single variable.
  • Allows for organizing data effectively.
  • Comes under sequence data types as it contains a sequence of data.
  • Lists can store elements of different data types (integers, strings, booleans, floats, objects) in the same list.
  • Homogeneous and heterogeneous collections are allowed.

Creating Lists

# Example of creating lists
roll_numbers = [1, 2, 3, 4, 5]
names = ['John', 'Jane', 'Doe']
mixed_list = [1, 'Hello', True, 10.5]

Characteristics of Lists

  • Ordered: Items have a defined order that will not change.
  • Mutable: Can be altered after creation (add, remove, change elements).
  • Allow Duplicates: Lists can have multiple occurrences of the same element.

Common List Operations

Accessing Elements

  • Use index to access individual elements.
roll_numbers[0]  # Access first element
roll_numbers[-1]  # Access last element (using negative indexing)

Slicing

  • Extract subparts of list using slicing.
numbers = [10, 0, -1, 7]
numbers[1:3]  # Slicing from index 1 to 2
numbers[:3]  # Slicing from start to index 2
numbers[1:]  # Slicing from index 1 to end
numbers[::2]  # Slicing with step

List Functions and Methods

Adding Elements

  • Append: Adds a single element at the end.
numbers.append(45)
  • Insert: Adds an element at a specified index.
numbers.insert(2, 45)
  • Extend: Adds multiple elements at the end.
numbers.extend([45, 46, 47])

Removing Elements

  • Remove: Removes the first occurrence of specific value.
numbers.remove(45)
  • Pop: Removes element at a specific index (default is last element) and returns it.
numbers.pop()  # Removes last element
numbers.pop(1)  # Removes element at index 1

Utility Functions

  • Len: Returns length of the list.
len(numbers)
  • Min: Returns minimum value.
min(numbers)
  • Max: Returns maximum value.
max(numbers)
  • Sort: Sorts the list.
numbers.sort()
  • Reverse: Reverses the list order.
numbers.reverse()
  • Index: Finds index of the first occurrence of a value.
numbers.index(7)
  • Count: Counts occurrences of a value.
numbers.count(7)

Practical Example

numbers = [10, 0, -1, 7]
# Adding elements
numbers.append(45)
numbers.insert(2, 32)
numbers.extend([50, 60])
# Removing elements
numbers.remove(0)
numbers.pop()
# Utility operations
length = len(numbers)  # 10
minimum = min(numbers)  # -1
maximum = max(numbers)  # 60
numbers.sort()
numbers.reverse()

Final Remarks

  • Lists are a powerful and flexible data structure in Python, offering a variety of operation methods.
  • Next video will cover the Random Module and a new coding exercise.