Python Lists Lecture Notes

Introduction

• Host: Ivan Jetty
• Topic: Working with lists in Python

Overview of Lists

• Lists in Python are similar to arrays in C/C++/Java.
• They can contain various data types (numbers, strings, etc.).

Creating a List

• Syntax: nums = [25, 12, 636, 95, 14]
• Lists are defined using square brackets.

Accessing List Elements

• Indexing:
  • First element: nums[0] returns 25
  • Last element: nums[-1] returns 14
  • Subrange (e.g., from third element to end): nums[2:] returns [636, 95, 14]
  • Negative indexing works as well (e.g., nums[-5] returns 25).

List of Different Data Types

• Example list with mixed types: values = [9.5, "My Name", 25]
• Lists can contain different types of data (unlike arrays in languages such as C, C++ where the type is fixed).

Nested Lists

• Example of a nested list: mil = [nums, names]
• mil contains both numbers and strings.

List Methods and Mutability

• Lists are mutable, which means you can change their contents.
• Common methods:
  • append(value): Adds an element at the end.
  • insert(index, value): Inserts an element at a specific index.
  • remove(value): Removes the first occurrence of a value.
  • pop(index): Removes and returns an element at a specific index (or last element if no index is provided).
  • clear(): Clears all elements from the list.
  • extend([values]): Adds multiple elements to the end of the list.

Examples of List Operations

• Appending a value: nums.append(45)
• Inserting a value: nums.insert(2, 2077)
• Removing a value: nums.remove(14)
• Using pop without an index removes the last added element.

Deleting Multiple Values

• del nums[2:]: Deletes all elements from index 2 to the end.

Built-in Functions for Lists

• min(nums): Returns the minimum value in the list.
• max(nums): Returns the maximum value in the list.
• sum(nums): Returns the sum of all elements.
• sort(): Sorts the elements of the list in ascending order.

Conclusion

• Lists in Python are versatile:
  • Can hold different data types.
  • Can be modified with various methods.
  • Support indexing and slicing.
• Encouraged to experiment with list methods and refer to Python documentation for more information.