Python Notes: Basics

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Basic Python Notes

What is Python?

Python is a high-level, interpreted programming language widely used in:

Scientific computing
Artificial Intelligence
Web development
Data analysis
Automation
Physics simulations

1. Writing Your First Python Program


print("Hello World")

OUTPUT

Hello World

print() is used to display output on the screen.

2. Variables in Python

Variables store data.


x = 10
name = "Physics"
pi = 3.14

Rules for Variables Cannot start with a number No spaces allowed. Case-sensitive.

Example:


age = 20
Age = 30

Both are different variables.

3. Data types

These are the primary basic data types used in Python, classified in the following table. There are more data types like list, tuple, range, frozenset, binary types, and null types.

Data Type Example
Integer (`int`) `5`
Float (`float`) `3.14`
String (`str`) `"hello"`
Boolean (`bool`) `True`, `False`

Data Type	Example
Integer (`int`)	`5`
Float (`float`)	`3.14`
String (`str`)	`"hello"`
Boolean (`bool`)	`True`, `False`

Example:


a = 5
b = 2.5
c = "Einstein"
d = True

4. Taking User Input


name = input("Enter your name: ")
print(name)

Numerical Input


x = int(input("Enter a number: "))

For decimal numbers:


x = float(input("Enter value: "))

5. Basic Operator

Arithmetic Operators

Operator	Meaning
`+`	Addition
`-`	Subtraction
`*`	Multiplication
`/`	Division
`//`	Floor Division
`%`	Modulus
`**`	Power

Example:


a = 10
b = 3

print(a + b)
print(a - b)
print(a * b)
print(a / b)
print(a % b)
print(a ** b)

6. Conditional Statements

if Statement


x = 10

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

if-else


x = 2

if x % 2 == 0:
    print("Even")
else:
    print("Odd")

if-elif-else


marks = 75

if marks >= 90:
    print("A")
elif marks >= 70:
    print("B")
else:
    print("C")

7. Loops in Python

for loop


for i in range(5):
    print(i)

OUTPUT


Run started
Initializing environment
Installing packages
Running code
0
1
2
3
4
Run completed in 43.69999998807907ms

while loop


x = 1

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

OUTPUT


Run started
Initializing environment
Installing packages
Running code
1

2

3

4

5

Run completed in 43.69999998807907ms

8. Functions

Functions help reuse code.

Creating a Function


def greet():
    print("Hello")

Calling Function


greet()

Function with Parameters


def add(a, b):
    return a + b

result = add(2, 3)
print(result)

OUTPUT


Run started
Initializing environment
Installing packages
Running code
5

Run completed in 6982.300000000745ms

9. Lists

Lists store multiple values. in a list position of elements mapped as 0, 1, 2... This means the very first entry of a list element is assigned to a position index of 0, the second one has a position index of 1, and so on.


numbers = [1, 2, 3, 4]

Accessing Elements

To access an element within a list, we need to call it by its position index.

print(numbers[0])

Adding Elements


numbers.append(5)

Example:


numbers = [1, 2, 3, 4]
print(numbers[0])
numbers.append(5)
print(numbers)

OUTPUT


Run started
Initializing environment
Installing packages
Running code
1

[1, 2, 3, 4, 5]


Run completed in 27.200000001117587ms

Loop Through List


for x in numbers:
    print(x)

Example:


numbers = [1, 2, 3, 4]
for x in numbers:
    print(x)

OUTPUT


Run started
Initializing environment
Installing packages
Running code
1

2

3

4

Run completed in 72.09999999962747ms

10. Tuples are immutable lists.

t = (1, 2, 3)

Cannot change elements after creation.

11. Dictionaries

Store data as key-value pairs.


student = {
    "name": "Rahul",
    "age": 20
}

Access value:


print(student["name"])

12. Strings


text = "Physics"

String Operations


print(text.upper())
print(text.lower())
print(len(text))

Example:


text = "Physics"
print(text.upper())
print(text.lower())
print(len(text))

OUTPUT


Run started
Initializing environment
Installing packages
Running code
PHYSICS

physics

7

Run completed in 75.69999999925494ms

13. File Handling

Writing to File


file = open("data.txt", "w")
file.write("Hello")
file.close()

Reading File


file = open("data.txt", "r")
print(file.read())
file.close()

14. Exception Handling Used to handle errors.


try:
    x = 10 / 0
except:
    print("Error occurred")

OUTPUT


Run started
Initializing environment
Installing packages
Running code
Error occurred

Run completed in 5855.799999998882ms

Python has thousands of modules, categorized into those built into the language and those created by the community. One can find 200+ native modules in the official "Python Module Index."

Core standard library

Basically, these are pre-installed with Python and handle basic system tasks.

os: Interact with operating system (files, directories)

sys: System-specific parameters and functions

math: advanced mathematical operations

datetime: work with dates and times.

random: Generates random numbers and choices

json: Encode and decode JSON data.

re: Regular expression operations for text searching

collections: Specialized container types like counter or deque.

Web and networking

urllib: Handle URLs and HTTP requests

http.server: Set up a simple local web server

socket: low-level networking interface

webbrowser: open links in the default browser.

not discussable for core physics. Generally math- and simulation-dependent modules are used here.

Third-party modules

Those are installed separately before assignment, usually via PyPI, which hosts over 800,000 projects.

Data-science: Numpy(arrays), Pandas(dataframes), SciPy(science)

Visualization: Matplotlib, Seaborn, Plotly Machine learning: Scikit-learn, TensorFlow, PyTorch.

Web-Frameworks: Django,Flask.

Automation: Requests(HTTP),BeautifulSoup(sracpping).

15. Importing Modules


import math

print(math.sqrt(25))

OUTPUT


Run started
Initializing environment
Installing packages
Running code
5.0

Run completed in 9985.400000002235ms

16. Object-Oriented Programming (Basic)


class Student:

    def __init__(self, name):
        self.name = name

    def show(self):
        print(self.name)

s1 = Student("Einstein")
s1.show()


Run started
Initializing environment
Installing packages
Running code
Einstein

Run completed in 5041.5ms

17. NumPy Basics

Useful for scientific computing. useful for computational theoretical physics.


import numpy as np

a = np.array([1,2,3])

print(a)

OUTPUT


Run started
Initializing environment
Installing packages
Running code
[1 2 3]

Run completed in 10387.79999999702ms

18. Matplotlib Basics

Used for plotting graphs. highly useful for computational and theoretical physics.

Example:

Let's plot the simplest 2-D graph


import matplotlib.pyplot as plt

x = [1,2,3]
y = [1,4,9]

plt.plot(x, y)
plt.show()

OUTPUT


Run started
Initializing environment
Installing packages
Running code













Run completed in 27098.5ms

Summarizing

19. Important Python Concepts

Concept	Meaning
Variable	Stores data
Function	Reusable block of code
Loop	Repeats code
Condition	Decision-making
List	Collection of data
Module	Prewritten code library
Class	Blueprint for objects

20. Common Python Libraries

Library	Use
NumPy	Numerical computation
Matplotlib	Plotting
Pandas	Data analysis
SciPy	Scientific computing
SymPy	Symbolic mathematics

"These articles and the views expressed as notes are my own interpretations made to easily organize and simplify the complexity of higher studies and do not represent the official views of any professor or their institution. Collection of personal notes and ideas as portfolio"

Reference:

Python official documentation

Book: Scientific computing in Python by Abhijit Kar Gupta

Book: Scientific Computing with Python by Claus Führer, Olivier Verdier, Jan Erik Solem.

PHYSICXION

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Python Notes: Basics

Basic Python Notes

What is Python?

1. Writing Your First Python Program

2. Variables in Python

3. Data types

Data Type Example
Integer (`int`) `5`
Float (`float`) `3.14`
String (`str`) `"hello"`
Boolean (`bool`) `True`, `False`

4. Taking User Input

5. Basic Operator

6. Conditional Statements

7. Loops in Python

8. Functions

9. Lists

10. Tuples are immutable lists.

11. Dictionaries

12. Strings

13. File Handling

14. Exception Handling Used to handle errors.

15. Importing Modules

17. NumPy Basics

18. Matplotlib Basics

Summarizing

19. Important Python Concepts

20. Common Python Libraries

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⚠️ Stay Safe Online

Python Notes: Basics

Basic Python Notes

What is Python?

1. Writing Your First Python Program

2. Variables in Python

3. Data types

Data TypeExampleInteger (int)5Float (float)3.14String (str)"hello"Boolean (bool)True, False

4. Taking User Input

5. Basic Operator

6. Conditional Statements

7. Loops in Python

8. Functions

9. Lists

10. Tuples are immutable lists.

11. Dictionaries

12. Strings

13. File Handling

14. Exception Handling Used to handle errors.

15. Importing Modules

17. NumPy Basics

18. Matplotlib Basics

Summarizing

19. Important Python Concepts

20. Common Python Libraries

Join the conversation

Data Type Example
Integer (`int`) `5`
Float (`float`) `3.14`
String (`str`) `"hello"`
Boolean (`bool`) `True`, `False`