Python for Beginners and Intermediate Developers — A Complete Guide

Source: Dev.to

Why Python?

• Beginner‑friendly
• Easy to read and write
• Used in web development, data science, AI/ML, automation, DevOps, game development, and more
• Supported by a huge community
• Available on all major operating systems

1. Python Basics

1.1 Variables

name = "Farhad"
age = 20
is_active = True

print(name)
print(age)
print(is_active)

Explanation

• Strings use quotes.
• Integers do not use quotes.
• Boolean values start with a capital letter: True or False.

1.2 Data Types

x = 10              # int
pi = 3.14           # float
name = "Python"     # str
is_ok = True        # bool
items = [1, 2, 3]   # list
points = (4, 5)     # tuple
user = {"name": "Ali", "age": 25}  # dict

1.3 Input From User

username = input("Enter your name: ")
print("Hello, " + username)

1.4 Conditional Statements (if, elif, else)

age = 18

if age > 18:
    print("You are an adult.")
elif age == 18:
    print("You just turned 18!")
else:
    print("You are under 18.")

2. Working With Loops

2.1 For Loop

for i in range(5):
    print("Number:", i)

Explanation: range(5) generates numbers 0 to 4.

2.2 While Loop

count = 1

while count <= 5:
    print(count)
    count += 1

3. Functions

def greet(name):
    print("Hello,", name)

greet("Farhad")
greet("Klie")

4. Lists, Tuples, and Dictionaries

4.1 Lists

fruits = ["apple", "banana", "orange"]
fruits.append("mango")

print(fruits)

4.2 Tuples (immutable)

point = (10, 20)
print(point[0])

4.3 Dictionaries

person = {
    "name": "Farhad",
    "age": 20
}

print(person["name"])

5. Intermediate Python Concepts

5.1 List Comprehension

numbers = [1, 2, 3, 4, 5]
squares = [x * x for x in numbers]

print(squares)

5.2 Lambda Functions

square = lambda x: x * x
print(square(5))

5.3 Map, Filter, Reduce

map()

nums = [1, 2, 3]
doubled = list(map(lambda x: x * 2, nums))
print(doubled)

filter()

nums = [1, 2, 3, 4, 5, 6]
even = list(filter(lambda x: x % 2 == 0, nums))
print(even)

5.4 Error Handling (try/except)

try:
    number = int(input("Enter a number: "))
    print("You entered:", number)
except ValueError:
    print("Invalid number. Please enter digits only.")

5.5 Working With Files

Write to a file

with open("data.txt", "w") as f:
    f.write("Hello, Python!")

Read from a file

with open("data.txt", "r") as f:
    content = f.read()
    print(content)

5.6 Object-Oriented Programming (OOP)

Class and Object Example

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def introduce(self):
        print(f"My name is {self.name}, and I am {self.age} years old.")

p1 = Person("Farhad", 20)
p1.introduce()

Explanation

• __init__ runs when an object is created.
• self refers to the current object.
• Methods are functions defined inside classes.

6. Python Best Practices

• Use meaningful variable names.
• Keep functions small and reusable.
• Comment your code when needed.
• Follow PEP 8 style guidelines.
• Use virtual environments for project dependencies.

7. What You Can Build With Python

• Web applications (Django, Flask, FastAPI)
• Machine learning models (TensorFlow, PyTorch)
• Automation scripts
• API services
• Chatbots
• Data visualization tools
• Games (pygame)

Python is limitless once you learn the foundations.

Conclusion

Python is the perfect starting point for beginners and a powerful tool for intermediate developers. With its clean syntax and rich ecosystem, you can quickly build anything—from small scripts to large‑scale applications.