Python Notes

 Python Notes 

$ python --version
Python 3.12.3

Python is platform independent 

 python virtual machine:

The Python Virtual Machine (PVM) is an abstract machine and a crucial component of the Python runtime environment. It is responsible for executing Python bytecode, which is a low-level, platform-independent representation of Python source code. 

It supports Virtual Environment :

Create virtual environment : 

$python3 -m venv myvenv #Will install on current folder 

Activate virtual environment: 

$ source myvenv/bin/activate

deactivate #To deactive 

 (myvenv) HostName@Current folder: 

print('Welcome to python training')

PIP:
pip (also known by Python 3's alias pip3) is a package manager (package management system) written in Python and is used to install and manage software packages.

pip install fastapi[all]

 pip freeze > requirements.txt

pip install requirements.txt 

pip list  

 

Variables:

 

username = "Praveen"

city = "Hyderabad"

state = 'TG'

age=40

print(f"Myname is {username} I am from {city} {state} and my age is {age}")

 

data1=int(input('Enter your value-1: '))

data2=int(input('Enter your value-1: '))

print(f"Total: {(data1) + (data2)}")

print(type(data1))

 

Conditions: 

 

if age>30:

print('your allowed to enter')

else:

print('Not Allowed')

  

If Condition with iteration:  

while True:

try:

age = int(input("Enter your age: "))

if 0 <= age <= 101:

break

else:

print("Please enter a valid age between 0 and 101.")

except ValueError:

print("Invalid input! Please enter a number.")

print(f"Your age is: {age}")

 

#################### Array ####################

# array declarations 

 

usernames = ['Bramha','Vishnu','Mahesh']

print(usernames)

# ['Bramha', 'Vishnu', 'Mahesh']

for username in usernames:

print(f"User Details : {username}")

for userindex,username in enumerate(usernames):

print(f"Index : {userindex} --> {username.upper()}")

for userindex,username in enumerate(usernames,start=1):

print(f"Index : {userindex} --> {username.upper()}")

 

Problem - Created and fill array with user input:

# initiating empty array

user_data =[]

data = int(input("How many numbers to add: "))

for i in range(data):

num = int(input(f" Enter number : "))

user_data.append(num)

print(f"values is array: {user_data}")

# calculate even or odd

for num in user_data:

if(num%2==0):

print(f"{num} is even")

else:

print(f"{num} is odd")

# calculate the addition if all numbers

res = 0

for num in user_data:

res +=num

print(f"addition res = {res}")

 

 

# Get Positive input 

 

def get_positive_input(prompt):

while True:

value = int(input(prompt))

if value > 0:

return value

else:

print("Enter a positive value greater than 0.")

data1 = get_positive_input("Enter your value-1: ")

data2 = get_positive_input("Enter your value-2: ")

# Addition

c = data1 + data2

print(f"Addition is: {c}")

#################### Functions ####################

 

# Declare function

def showwelcome():

print("Welcome to the function")

showwelcome()

def calculatedata(x,y):

return print(x+y)

calculatedata(3,2)

def multireturndata(x,y):

return x,y

a,b = multireturndata(2,5)

 

#################### Class #################### 

class user:

def showwelcome(self):

print("Welcome to the class")

def calculatedata(self,x,y):

print(f"Addition is {x+y}")

# using class

uc = user()

uc.showwelcome()

uc.calculatedata(2,3)

#########

 

class user:

def __init__(self): # __int__ - Constructor. It is self called

print('Defult constructor called')

user = user()

#output - Defult constructor called

class user:

def __init__(self,uname,email,city):

self.uname = uname

self.email = email

self.city = city

user = user('Praveen','praveen@mail.com','Hyd')

print(user.uname,user.email,user.city)

#Output - Praveen praveen@mail.com Hyd

class user:

def showcity(self): # Defined the function, not self Constructor

city = input('Enter city : ')

print('city will be called ', city)

user = user() # Loading call

user.showcity() # Calling method

#Output - Enter city : Hyderabad / city will be called Hyderabad

class user:

def __init__(self,uname,email,city):

self.uname = uname

self.email = email

self.city = city

def __str__(self): # This function auto called when your printing object

return f"{self.uname} - {self.email} - {self.city}"

user = user('Praveen','praveen@mail.com','Hyd')

print(user)

#output - Praveen - praveen@mail.com - Hyd

 #####

 

### ribclass.py ### 

 

from abc import ABC,abstractmethod

class RBI(ABC):

@abstractmethod # abstractmethod means mandatory in chaild class

def withdraw(self):

pass

@abstractmethod

def deposit(self):

pass

@abstractmethod

def checkBalance(self):

pass

def openSalaryAccount(self): # No abstractmethod so this function not mandatory in clild

pass

 

 ### ribclass.py closed ###

 

### sbiclass.py ####

 

from rbiclass import RBI # Importing RBI class from rbiclass.py file

class SBI(RBI):

def withdraw(self):

print("withdraw from SBI")

def deposit(self):

print("deposit from SBI")

def checkBalance(self):

print("checkbalance from SBI")

def openFD(self):

print('FD account opened in SBI')

 

### sbiclass.py closed ###

 

### Bankingmail.py ##### 

 

from sbiclass import SBI # Importing SBI class from sbiclass.py file

bank1 = SBI()

bank1.checkBalance()

bank1.openSalaryAccount()

bank1.deposit()

 

### Bankingmail.py closed ##### 

 

# Output - checkbalance from SBI / deposit from SBI 

 

  

 ############ FASTAPI ###########

 

from fastapi import FastAPI

app = FastAPI()

users = ['Admin','Manager','QA']

@app.get("/Welcome")

def Show_Welcome():

return{"Message":"Welcome to FASTAPI"}

# RUN - /Documents/python-ansible/python-training/day-2/fastapi$ uvicorn crudapp:app

@app.get("/loadusers")

def showusers():

return {"message":users}

# Troubleshoot - sudo lsof -i :8000; kill -9 <PID>

 

###########

 

# database.py - File  

from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

SQL_DB = "sqlite:///./mytest.db"

engine = create_engine(
SQL_DB, connect_args={"check_same_thread": False}

)
SessioLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

Base = declarative_base()


def get_connection():
db = SessioLocal()
try:
yield db
finally:
db.close()



-----

# schema.py - file name

from pydantic import BaseModel

# the data you are expecting from the client
class Base(BaseModel):

name: str
sclass: str
section: str


---

# models.py - File name

# schema represenation

from sqlalchemy import Column,String
from .database import Base

class Student(Base):
__tablename__="STUDENT"

name= Column(String,primary_key=True)
sclass= Column(String)
section= Column(String)

class staff(Base):

__tablename__="STAFF"

name= Column(String,primary_key=True)

sclass= Column(String)

section= Column(String)

---

#studentapp.py - File

from fastapi import FastAPI,APIRouter,Depends,status
from fastapi.params import Body
from sqlalchemy.orm import Session
from .. import schema,models
from .. database import engine,get_connection

router= APIRouter(tags=["Student Application"])

@router.post("/addstudent")

def studentRegister(student:schema.Base, db:Session=Depends(get_connection)):

newdata = models.Student(**student.dict())

db.add(newdata)

db.commit()

return {"message":"db created"}

@router.post("/addstaff")

def staffregister(staff:schema.Base, db:Session=Depends(get_connection)):

newdata = models.staff(**staff.dict())

db.add(newdata)

db.commit()

return {"message":"staff created"}

-----

# Crudapp.py - File

from fastapi import FastAPI
from .routers import studentapp

from .database import engine,get_connection
from . import models,schema

# create table in db while loading model class
models.Base.metadata.create_all(bind=engine)
app=FastAPI()

app.include_router(studentapp.router)

 

 

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Key Difference Between List, Array and Tuple

Feature	List	Array	Tuple
Mutability	Mutable	Mutable	Immutable
Data Type	Can store different types	Stores elements of the same type	Can store different types
Ordered	Yes	Yes	Yes
Performance	Slower for numerical operations	Faster for numerical operations	Faster than lists (due to immutability)
Memory Efficiency	Less efficient	More efficient for large data	More memory-efficient than lists
Usage	General-purpose collection	Numerical and homogeneous data	Fixed data, constants
Syntax	[ ]	array()	( )
Indexing	Supported	Supported	Supported