Master Python Basics: Variables, Loops, Data Structures, and OOP

Python Basics

According to Guido van Rossum, Python is a high‑level language designed for readability, allowing programmers to express ideas with few lines of code. It is used for data science, web development, and machine learning.

Variables

Variables store values; examples:

one = 1
two = 2
some_number = 10000
# boolean examples
boolean_true = True
boolean_false = False
my_name = "Leandro Tk"
book_price = 15.80

Control Flow – Conditional Statements

if True:
    print("Hello Python If")
if 2 > 1:
    print("2 is greater than 1")
if 1 > 2:
    print("1 is greater than 2")
else:
    print("1 is not greater than 2")
if 1 > 2:
    print("1 is greater than 2")
elif 2 > 1:
    print("1 is not greater than 2")
else:
    print("1 is equal to 2")

Loops and Iteration

num = 1
while num <= 10:
    print(num)
    num += 1

loop_condition = True
while loop_condition:
    print("Loop Condition keeps: %s" % (loop_condition))
    loop_condition = False

for i in range(1, 11):
    print(i)

Lists – Collections

my_integers = [1, 2, 3, 4, 5]
print(my_integers[0])  # 1
relatives_names = ["Toshiaki", "Juliana", "Yuji", "Bruno", "Kaio"]
print(relatives_names[4])  # Kaio
bookshelf = []
bookshelf.append("The Effective Engineer")
bookshelf.append("The 4 Hour Work Week")
print(bookshelf[0])

Dictionaries – Key‑Value Data Structure

dictionary_example = {
    "key1": "value1",
    "key2": "value2",
    "key3": "value3"
}

dictionary_tk = {
    "name": "Leandro",
    "nickname": "Tk",
    "nationality": "Brazilian"
}
print("My name is %s" % (dictionary_tk["name"]))

Iterating Over Dictionaries

for key in dictionary:
    print("%s --> %s" % (key, dictionary[key]))
for key, value in dictionary.items():
    print("%s --> %s" % (key, value))

Classes & Objects

class Vehicle:
    def __init__(self, number_of_wheels, type_of_tank, seating_capacity, maximum_velocity):
        self.number_of_wheels = number_of_wheels
        self.type_of_tank = type_of_tank
        self.seating_capacity = seating_capacity
        self.maximum_velocity = maximum_velocity

    @property
    def number_of_wheels(self):
        return self._number_of_wheels

    @number_of_wheels.setter
    def number_of_wheels(self, number):
        self._number_of_wheels = number

    def make_noise(self):
        print('VRUUUUUUUM')

Encapsulation

Encapsulation hides an object’s internal state and requires interaction through methods, using public and non‑public (prefixed with an underscore) attributes and accessor methods.

Inheritance

class Car:
    def __init__(self, number_of_wheels, seating_capacity, maximum_velocity):
        self.number_of_wheels = number_of_wheels
        self.seating_capacity = seating_capacity
        self.maximum_velocity = maximum_velocity

class ElectricCar(Car):
    def __init__(self, number_of_wheels, seating_capacity, maximum_velocity):
        super().__init__(number_of_wheels, seating_capacity, maximum_velocity)