Overview
This lecture covers the fundamental concepts of Python programming, including variables, data types, operators, collections, functions, object-oriented programming, file handling, loops, conditionals, and importing modules.
Introduction to Programming and Python
- Programming involves writing code to give instructions to a computerβs processor.
- Software is a collection of code or programs.
- Python is a beginner-friendly programming language.
Variables and Data Types
- A variable is a container to temporarily store data in a program.
- Data types in Python include:
- String (text, e.g., "Vamsi")
- Integer (whole numbers, e.g., 10000)
- Float (numbers with decimals, e.g., 3.14)
- Complex (numbers with real and imaginary parts)
- Boolean (True or False)
- Sequence (list, tuple, range)
- Mapping (dictionary)
- Set (unordered collection of unique items)
Input and Output
- The
input() function takes input from the user.
- The
print() function displays output.
type() checks the variable's data type.
Operators in Python
- Arithmetic operators: +, -, *, /, %, **, //
- Assignment operators: =, +=, -=, *=, /=, %=
- Comparison operators: >, <, >=, <=, ==, !=
- Logical operators: and, or, not
- Identity operators: is, is not (used for object comparison)
- Membership operators: in, not in
- Bitwise operators: &, |, ^, ~, <<, >>
Collections: List, Tuple, Set, Dictionary
- List: ordered, changeable, allows duplicates, uses [ ].
- Tuple: ordered, unchangeable, allows duplicates, uses ( ).
- Set: unordered, changeable, no duplicates, uses { }.
- Dictionary: ordered, changeable, no duplicates, key-value pairs, uses { }.
Collection Methods
- List:
.append(), .insert(), .extend(), .remove(), .pop(), del
- Set:
.add(), .remove()
- Dictionary: access with keys,
.get(), .keys(), .values()
Conditionals and Loops
if, elif, else control flow based on conditions.while loop repeats code while a condition is true.for loop iterates over sequences or with range().
Functions
- Defined with
def keyword; reusable blocks of code.
- Arguments (parameters) are passed to functions.
return statement sends data back to the caller.- Lambda functions create anonymous, one-line functions.
Object-Oriented Programming
- Class: blueprint defining data (attributes) and methods (functions).
- Object: instance of a class with actual data.
__init__ method initializes object attributes.- Inheritance allows a class to use attributes and methods from another class.
File Handling
- Files are opened with
open(filename, mode).
- Modes: 'r' (read), 'w' (write), 'a' (append), 'x' (create).
.read(), .readline(), .write() are used for file operations.- Files should be closed with
.close().
Importing Modules
- Use
import module_name to use external modules (e.g., import math).
from module import component imports specific parts.from module import * imports everything from a module.*
Key Terms & Definitions
- Variable β temporary container to store data.
- Data Type β categorizes data (e.g., int, float, str, bool).
- Operator β symbol performing operations on data.
- List β ordered, mutable sequence of items.
- Tuple β ordered, immutable sequence of items.
- Set β unordered, unique collection of items.
- Dictionary β collection of key-value pairs.
- Function β reusable block of code.
- Class β blueprint for objects.
- Object β instance of a class.
- Inheritance β child class inherits from parent class.
- File Handling β reading/writing files in Python.
- Module β external Python file with reusable code.
Action Items / Next Steps
- Practice writing and running Python code covering each concept.
- Try creating and using lists, tuples, sets, and dictionaries.
- Experiment with defining functions, classes, and file operations in Python.
- Review the use of modules and try importing and using the
math module.