Overview
This lecture provides a beginner-friendly introduction to Python programming, covering installation, basic syntax, variables, data types, operators, control flow, loops, data structures (lists and tuples), and essential built-in functions.
Getting Started with Python
- Python is a multi-purpose language used for web development, data science, machine learning, and automation.
- Download Python from python.org and install the latest version, ensuring you add Python to your system PATH.
- Use a code editor like PyCharm Community Edition for writing Python code.
Writing Your First Program
- Create a new Python project and file, then write
print("Hello World") to output a message.
- Strings are sequences of characters surrounded by single or double quotes.
- The
print function displays output in the terminal.
Variables and Data Types
- Variables store data temporarily in memory (e.g.,
age = 20).
- Variable names should use underscores to separate words for readability.
- Python supports numbers (integers, floats), strings, and booleans (
True/False).
- Python is case-sensitive (
True ≠ true).
User Input and Type Conversion
- Use
input() to receive user data as strings.
- Convert input strings to integers or floats using
int(), float(), or to other types as needed.
- String concatenation combines strings with
+.
- Convert other data types to strings using
str().
String Methods
- Strings are objects with methods such as
.upper(), .lower(), .find(), .replace().
- Strings are immutable; methods return new strings.
- Use
in to check if a substring exists in a string.
Arithmetic and Comparison Operators
- Use
+, -, *, / (float), // (integer), % (modulus), and ** (exponent) for arithmetic.
- Augmented assignment operators (
+=, -=, etc.) simplify variable updates.
- Operator precedence follows math rules; parentheses alter order.
- Comparison operators:
>, >=, <, <=, == (equality), != (not equal).
Logical Operators and Control Flow
- Logical operators:
and, or, not.
if, elif, else statements execute code blocks conditionally.- Indentation defines code blocks in Python.
Loops
while loops repeat code as long as a condition is true; increment loop variables to avoid infinite loops.for loops iterate over sequences like lists or ranges.
Lists
- Lists store ordered collections of items, defined with square brackets (e.g.,
[1, 2, 3]).
- Access items by index (zero-based), including negative indices for reverse order.
- Methods:
.append(), .insert(), .remove(), .clear(), and the in operator.
- Use
len() to get the number of items.
Tuples
- Tuples are immutable sequences defined with parentheses (e.g.,
(1, 2, 3)).
- Support
.count() and .index() methods, but not modification.
- Use tuples when data should not change.
Key Terms & Definitions
- Variable — A label for a memory location storing data.
- String — A sequence of characters (text).
- Boolean — A data type with two values:
True or False.
- List — An ordered, mutable collection of items.
- Tuple — An ordered, immutable collection of items.
- Function — A reusable block of code (e.g.,
print()).
- Method — A function associated with an object (e.g.,
str.upper()).
- Operator — A symbol performing operations on variables and values.
Action Items / Next Steps
- Download and install Python from python.org.
- Install PyCharm Community Edition or another code editor.
- Complete practice exercises: check-in patient variables, basic calculator, and weight converter program.
- Explore string, list, and tuple methods in your own code.