Welcome to the Introduction of Python

Python is a beginner-friendly programming language with simple syntax and powerful libraries, making it ideal for tasks like data analysis, web development, and automation. It’s perfect for new learners to focus on creativity and problem-solving while exploring endless possibilities.

Basic Syntax and Structure

Python uses indentation to define blocks of code (e.g., loops, functions).
Statements in Python end without a semicolon.
Python code is clean and straightforward to write and read.
People use a style guide for writing clean, readable, and consistent Python code.
It improve readability and maintainability of Python projects.
It provides recommendations for formatting Python code, such as indentation, naming conventions, and line length.
For more details

Basic Arithmetic Operators

Operator	Type	Description	Example	Output
>	Relational	Greater than	5 > 3	True
<	Relational	Less than	3 < 5	True
>=	Relational	Greater than or equal to	5 >= 5	True
<=	Relational	Less than or equal to	3 <= 5	True
==	Relational	Equal to	5 == 5	True
!=	Relational	Not equal to	5 != 3	True
and	Logical	Returns True if both conditions are True	(5 > 3) and (4 > 2)	True
or	Logical	Returns True if at least one condition is True	(5 > 3) or (4 < 2)	True
not	Logical	Reverses the Boolean value	not (5 > 3)	False

Relational and Logical Operators

Operator	Type	Description	Example	Output
>	Relational	Greater than	5 > 3	True
<	Relational	Less than	3 < 5	True
>=	Relational	Greater than or equal to	5 >= 5	True
<=	Relational	Less than or equal to	3 <= 5	True
==	Relational	Equal to	5 == 5	True
!=	Relational	Not equal to	5 != 3	True
and	Logical	Returns True if both conditions are True	(5 > 3) and (4 > 2)	True
or	Logical	Returns True if at least one condition is True	(5 > 3) or (4 < 2)	True
not	Logical	Reverses the Boolean value	not (5 > 3)	False

Variables

Integers (int): 10, -5
Floats (float): 3.14, -0.5
Strings (str): "Hello", 'World'
Booleans (bool): True, False

If-Else Conditions

The if statement checks a condition. If the condition is true, the code inside it runs.
If it's false, the program skips the if block.

If x is greater than 5, it will print "x is greater than 5".

x = 10
if x > 5:
    print("x is greater than 5")

--------------------------------------- >> x is greater than 5

If it's not, nothing happens.

x = 1
    if x > 5:
        print("x is greater than 5")

--------------------------------------- >>

The if-else statement adds a backup plan.
If the condition in if is false, the code in the else block runs.

x = 1
    if x > 5:
        print("x is greater than 5")

--------------------------------------- >>

If y mod 2 equals 0, it will print "y is even".

y = 2
    if y % 2 == 0:
        print("y is even")
    else:
        print("y is odd")

--------------------------------------- >> y is even

Else y mod 2 not equals 0, it will print "y is odd".

y = 3
if y % 2 == 0:
    print("y is even")
else:
    print("y is odd")

--------------------------------------- >> y is odd

The if-elif-else statement checks multiple conditions in order.
Once it finds a condition that is true, it runs the matching block of code and skips the rest.
If none of the conditions are true, the else block runs.

If the grade is more than 90, the program prints "A".

grade = 100
if grade >= 90:
    print("A")
elif grade >= 70:
    print("B")
else:
    print("Fail")

--------------------------------------- >> A

Else-if (Elif) the grade is more than 70 but less than or equal to 90, the program prints "B".

grade = 85
if grade >= 90:
    print("A")
elif grade >= 70:
    print("B")
else:
    print("Fail")

--------------------------------------- >> B

Else the grade is less than 70, the program prints "Fail".

grade = 50
if grade >= 90:
    print("A")
elif grade >= 70:
    print("B")
else:
    print("Fail")

--------------------------------------- >> Fail

Loops

For Loops

A for loop repeats code for each item in a collection (like a list, range, or string).
It picks one item at a time and runs the code block for each.

for number in range(1, 4):
    print(number)

---------------------------------------

>> 1
>> 2
>> 3

fruits = ["apple", "banana"]
for fruit in fruits:
    print(fruit)

---------------------------------------

>> apple
>> banana

word = 'Hello'
    for letter in word:
    print(letter)

---------------------------------------

>> H
>> e
>> l
>> l
>> o

While Loops

A while loop repeats code as long as a condition is true.
It checks the condition before running the code block.
Make sure to update variables inside the loop to avoid infinite loops!

count = 1
while count <= 3:
    print(count)
    count += 1

---------------------------------------

>> 1
>> 2
>> 3

number = 5
while number > 0:
    print(number)
    number -= 1

---------------------------------------

>> 5
>> 4
>> 3
>> 2
>> 1

word = "Python"
index = 0
while index < len(word):
    print(word[index])
    index += 1

---------------------------------------

>> P
>> y
>> t
>> h
>> o
>> n

Functions

A function is a block of code that runs when it is called.
Functions can accept input through parameters and return output.
They help organize code and avoid repetition.

Defining and Calling Functions

If a function is called, it executes its code block.

def greet():
    print("Hello, world!")
    
greet()

--------------------------------------- >> Hello, world!

Functions with Parameters

Functions can take arguments as input to customize their behavior.

def greet(name):
    print(f"Hello, {name}!")
    
greet("Alice")

--------------------------------------- >> Hello, Alice!

Functions with Return Values

A function can return a value using the `return` keyword.

def add(a, b):
    return a + b
    
result = add(5, 3)
print(result)

--------------------------------------- >> 8

Using Default Parameters

Functions can have default values for parameters.

def greet(name="Guest"):
    print(f"Hello, {name}!")
    
greet()
greet("Alice")

---------------------------------------

>> Hello, Guest!
>> Hello, Alice!

Using Functions in Loops

Functions can be used inside loops for repeated actions.

def square(num):
    return num * num

for i in range(1, 4):
    print(square(i))

---------------------------------------

>> 1
>> 4
>> 9

Modules and Libraries

A module is a file containing Python code that can be reused in other programs.
A library is a collection of pre-written modules for performing specific tasks.
You can use the import statement to access a module or library.

Using Built-in Modules

Modules like math provide additional functionality.

import math

print(math.sqrt(16))
print(math.pi)

---------------------------------------

>> 4.0
>> 3.141592653589793

Using Custom Modules (OPTIONAL)

You can create your own modules and import them.

# In file mymodule.py
def greet(name):
    return f"Hello, {name}!"

# In your main program
import mymodule

print(mymodule.greet("Alice"))

--------------------------------------- >> Hello, Alice!

Installing and Using Libraries (OPTIONAL)

Third-party libraries can be installed using pip.

# Install requests library
# pip install requests

import requests

response = requests.get("https://api.github.com")
print(response.status_code)

--------------------------------------- >> 200

Using Aliases

You can use an alias to simplify module names.

import math as m

print(m.sqrt(25))

--------------------------------------- >> 5.0

Importing Specific Functions

You can import only specific functions from a module.

from math import sqrt, pi

print(sqrt(49))
print(pi)

---------------------------------------

>> 7.0
>> 3.141592653589793

Combining Modules

Modules can work together for more complex tasks.

import math
import random

radius = random.randint(1, 10)
area = math.pi * radius ** 2
print(f"Radius: {radius}, Area: {area}")

--------------------------------------- >> Radius: 7, Area: 153.93804002589985

Commonly used Modules

Some modules like math, csv, and json are built into Python.
Others, like third-party libraries, can be installed with pip.
However, during your practicals you would only be using built in modules
The flask and sqlite3 modules will be discssed in practical

Using the `math` Module

The math module provides mathematical functions.

import math

print(math.sqrt(16))  # Square root
print(math.factorial(5))  # Factorial
print(math.pi)  # Value of pi

---------------------------------------

>> 4.0
>> 120
>> 3.141592653589793

Using the `random` Module

The random module generates random numbers and selects random items.

import random

print(random.randint(1, 10))  # Random integer between 1 and 10
print(random.choice(["apple", "banana", "cherry"]))  # Random choice

---------------------------------------

>> 7
>> banana

Using `split` to Break Strings

The split() method splits a string into parts based on a delimiter.

text = "apple,banana,cherry"
fruits = text.split(",")  # Split by comma
print(fruits)

line = "Hello World"
words = line.split()  # Split by whitespace
print(words)

---------------------------------------

>> ['apple', 'banana', 'cherry']
>> ['Hello', 'World']

Using `readlines` to Read Files

The readlines() method reads all lines from a file into a list.

with open("example.txt", "w") as file:
    file.write("Hello\nWorld\nPython")
    
with open("example.txt", "r") as file: #write - w, read - r, ammend - a
    lines = file.readlines()
    print(lines)

--------------------------------------- >> ['Hello\n', 'World\n', 'Python']

The csv module helps in reading and writing CSV files.

import csv

with open("data.csv", "w") as file: #write - w, read - r, ammend - a
    writer = csv.writer(file)
    writer.writerow(["Name", "Age"])
    writer.writerow(["Alice", 25])
    
with open("data.csv", "r") as file:
    reader = csv.reader(file)
    for row in reader:
        print(row)

---------------------------------------

>> ['Name', 'Age']
>> ['Alice', '25']

Using a Custom Delimiter in CSV

The csv module allows you to set a custom delimiter for separating fields.

import csv

# Writing a CSV with a semicolon delimiter
with open("data_semicolon.csv", "w", newline="") as file:
    writer = csv.writer(file, delimiter=";")
    writer.writerow(["Name", "Age"])
    writer.writerow(["Alice", 25])
    writer.writerow(["Bob", 30])
    
# Reading the CSV with a semicolon delimiter
with open("data_semicolon.csv", "r") as file:
    reader = csv.reader(file, delimiter=";")
    for row in reader:
        print(row)

---------------------------------------

>> ['Name', 'Age']
>> ['Alice', '25']
>> ['Bob', '30']

Using the `json` Module

The json module is used to work with JSON data.

import json

data = {"name": "Alice", "age": 25}
json_string = json.dumps(data)  # Convert to JSON string
print(json_string)

parsed_data = json.loads(json_string)  # Convert back to dictionary
print(parsed_data["name"])

---------------------------------------

>> {"name": "Alice", "age": 25}
>> Alice

Navigation

Welcome to the Introduction of Python

Basic Syntax and Structure

Variables

If-Else Conditions

Loops

For Loops

While Loops

Functions

Defining and Calling Functions

Functions with Parameters

Functions with Return Values

Using Default Parameters

Using Functions in Loops

Modules and Libraries

Using Built-in Modules

Using Custom Modules (OPTIONAL)

Installing and Using Libraries (OPTIONAL)

Using Aliases

Importing Specific Functions

Combining Modules

Commonly used Modules

Using the math Module

Using the random Module

Using split to Break Strings

Using readlines to Read Files

Using a Custom Delimiter in CSV

Using the json Module

Using the `math` Module

Using the `random` Module

Using `split` to Break Strings

Using `readlines` to Read Files

Using the `json` Module