Lecture-11 Import_24-25

Introduction to Modules & Functions in Python

• Overview of COMP101 Introduction to Programming, Lecture 11 covering Modules & Functions in Python

Complexity in Programming

• Sometimes coding requires complex solutions to tackle problems.

• Example: The value of pi is utilized across various applications and must be calculated accurately.

• Instead of directly coding pi every time, a separate program or function can manage its value.

Sample Design for Calculating Pi

• Method:

  • Inscribe and circumscribe regular hexagons within a circle.

  • Calculate the circumference and diameter of these hexagons.

• Formula used: pi = circumference/diameter.

• Considerations include:

  • Decimal accuracy

  • Precision in calculations

  • Selection of the best algorithm.

Importance of Code Reuse

• Code reusability is crucial for programming efficiency.

• Avoids repetitive calculations, e.g., using pi.

• Create and save code as a module, which can then be invoked as needed.

Modules and Functions

• Saved programs are referred to as modules (files with .py extension).

• Functions encapsulated in these modules, e.g., calculations for pi, random number generation, etc.

• Key insight: Reliable functions are often pre-written by experts, tested for accuracy, and included in these modules.

Python Builtin Functions

• Python auto-loads common functions that are frequently used.

• Examples include: input(), print(), etc.

• Function definitions include empty parentheses to input desired data.

• A thorough list of functions can be found at: https://docs.python.org/3/library/functions.html.

Builtin Functions Overview

• A brief look at several builtin functions:

  • abs(), all(), any(), bin(), bool(), bytes(), float(), int(), len(), max(), min(), print(), sorted(), str(), zip(), etc.

• Note: Available functions may vary based on the Python version.

Importing Modules

• Some required functions may not be available as builtin functions and must be imported from external modules.

• Modules are Python programs usually with a .py extension and contained within a 'Python Library'.

• Use of modules requires importing, e.g., math, random, statistics, etc.

Focus on the Math Module

• The ‘math’ module includes essential mathematical functions necessary for various applications.

• Available functions in the 'math' module include:

  • sin(), cos(), tan(), sqrt(), pi, factorial(), etc.

Importing Modules and Using Functions

• Begin with import statements to utilize module functions:

  • Example: import math

  • Access pi value with: print(math.pi)

• Importance of using 'dot notation' to reference module functions clearly (e.g., math.sqrt()).

Importing Specific Functions

• It’s possible to import only specific functions from modules for efficiency:

  • Example: from math import pi allows direct access to pi without prefixing with the module name.

• Limitation: Importing specific functions limits access to the other functions within the module.

Accessing Built-in Functions in Python Shell

• To view all builtin functions:

  • Use commands:

    • import builtins

    • dir(builtins)

• Provides immediate availability in the code without needing imports.

Pre-Built Module Access

• To access pre-built modules:

  • Command: help() followed by:

  • help('modules') to see available modules.

Discovering Functions by Module

• To find out functions available in a specific module:

  • Example: import math

  • Command: dir(math) to list all functions within the math module.

Additional Resources

• Easily access Python's documentation online for functions and modules:

  • Direct link: https://docs.python.org/library/math

• Alternative: Search online for "Python math module" for extensive information.