Python 101 Series Part 2 - Guide to Python Programming

Welcome to the next blog in our Python 101 Blog Series! You can check this blog [Python 101 — Guide to Python Programming] if you missed the first part. 

Let’s dive into the topic:

1. Operators in Python

Today, we’ll explore Operators, which allow us to perform mathematical operations like addition, subtraction, multiplication, and more.

1. Addition (+)

Addition is used to add the numbers.

print(5 + 5)  
# Output: 10

2. Subtraction (-)

Subtraction is used to calculate the difference between numbers.

print(5 - 2)  
# Output: 3

3. Multiplication (*)

Multiplication gives the product of two numbers.

print(5 * 5)  
# Output: 25

4. Division (/)

Division divides one number by another.

print(10 / 2)  
# Output: 5.0

5. Modulus (%)

The modulus operator gives the remainder when one number is divided by another.

print(10 % 3)  
# Output: 1

6. Floor Division (//)

Floor division gives the quotient, excluding the decimal part.

print(10 // 3)  
# Output: 3

7. Power ()**

The power operator raises a number to the power of another.

print(3 ** 2)  
# Output: 9

Complex Expressions

In Python, expressions are evaluated using the PEMDAS rule:

• Parentheses
• Exponents
• Multiplication
• Division
• Addition
• Subtraction

It evaluates from left to right for operators of the same precedence.

print(3**2 / 2 * 3 / 3 + 6 - 4)  
# Output: 7.5

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2. Strings

Strings are text enclosed in single, double, or triple quotes.

print('Single Quotes')  
print("Double Quotes")  
print('''Triple Quotes''')

Task: How to write this: Hello, What’s up?

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3. Variables

Variables are containers that hold data. Python automatically determines the type of a variable based on its value.

number = 10  
# Here, the value 10 is assigned to the variable `number`.

Types of Variables

• Numeric: Numbers like 10 or 3.14
• String: Text like “Hello”
• Boolean: True or False

Bonus: Check a variable’s type using the type() function:

print(type(number))  
# Output: <class 'int'>

Rules for Naming Variables

1. Use letters, numbers, or underscores.
2. Don’t start with a number.
3. Avoid reserved keywords like if, else, etc.
4. Don’t use spaces in variable names.

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4. Input Variables

Input variables allow us to take user input and store it in a variable.

name = input("What is your name? ")  
greeting = "Hello"  
print(greeting, name)  
# If the user enters "Saadat", the output will be: Hello Saadat

Note: The input() function always returns a string. Convert it to another type if needed.

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5. Conditional Operators

Conditional operators are used to compare values.

print(10 == 10)  # Equal to  
print(10 != 5)   # Not equal to  
print(10 < 15)   # Less than  
print(10 > 5)    # Greater than  
print(10 >= 10)  # Greater than or equal to  
print(10 <= 20)  # Less than or equal to

Simple Program:

age_of_student = 4  
required_age_at_school = 5  
print(age_of_student >= required_age_at_school)  
# Output: False

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6. Type Conversion

Type conversion is used to convert a variable from one type to another.

Implicit Conversion

Python does this automatically where possible.

x = 10 + 2.5  
print(type(x))  
# Output: <class 'float'>

Explicit Conversion

You can convert types manually using int(), float(), or str().

age = input("Enter your age: ")  
age = int(age)  # Converts the string input into an integer

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7. If, Else, and Elif Statements

These are used to check conditions in your program. If the condition is `True` the block of code under the if will execute, if the condition is `False` then the else part will be executed. The elif is used where you need to add extra conditions.

if student_score >= 60:  
    print("Congrats! You passed.")  
elif student_score == 50:  
    print("You barely passed. Work harder!")  
else:  
    print("You failed. Better luck next time!")

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8. Loops

Loops are used to repeat a block of code. The loop will execute until the condition/limit is hit.

There are two types of loops `while` and `for`.

while loop:

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

for loop:

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

Breaking a loop:

fruits = ['Apple', 'Banana', 'Orange', 'Mango']  
for fruit in fruits:  
    print(fruit)  
    if fruit == 'Orange':  
        break

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9. Functions

Functions are blocks of code designed to perform specific tasks.

Built-in Functions:

Examples: print(), type(), len()

User-Defined Functions:

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

greet("Saadat")  
# Output: Hello Saadat

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10. Importing Libraries

Libraries extend Python’s capabilities. Examples: math, statistics, sklearn.

import math  
import statistics  

print("Value of Pi:", math.pi)  
numbers = [10, 20, 30, 40]  
print("Average:", statistics.mean(numbers))

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