Notesale: Turn your study into money

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1
...
append(5)
my_list
...
remove(3)
element = my_list
...
clear()

Other List Methods
my_list
...
reverse()
my_list
...
Tuples
Creating a Tuple
my_tuple = (1, 2, 3, 'a', 'b')

Accessing Elements
print(my_tuple[1])

es

# Remove element with value 3
# Remove and return element at index 2
# Remove all elements

# Output: 2

Slicing
print(my_tuple[1:3])

# Output: (2, 3)

Tuple Unpacking
a, b, c = (1, 2, 3)

# Assign 1 to a, 2 to b, 3 to c

Tuple Methods
my_tuple
...
index('a')

# Count occurrences of 1
# Find the index of 'a'

Note: Tuples are immutable, meaning elements cannot be modified after creation
...
Sets

Creating a Set

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my_set = {1, 2, 3, 'a'}

Adding/Removing Elements
my_set
...
remove(2)
my_set
...
isdisjoint(set2)
set1
...
Dictionaries
Creating a Dictionary
my_dict = {"name": "John", "age": 25, "city": "New York"}

Accessing Elements
print(my_dict["name"])
print(my_dict
...
com"
my_dict["age"] = 26

# Add new key-value pair
# Modify existing value

Removing Elements
del my_dict["city"]
my_dict
...
clear()

De

# Delete the key-value pair 'city'
# Remove and return value of 'email'
# Remove all elements

Iterating Over a Dictionary

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for key, value in my_dict
...
keys()
my_dict
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items()

cod

# Get all keys
# Get all values
# Get all key-value pairs

2
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Creating a Class
class MyClass:
def __init__(self, name):
self
...
name}!")
# Creating an object (instance of MyClass)
obj = MyClass("Alice")
obj
...


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

2
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class Employee:
company = "Google"

# Class attribute

def __init__(self, name):
self
...
company) # Output: Google
print(emp2
...


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emp1
...
company) # Output: Amazon
print(emp2
...
Methods

Instance Methods


Operate on object instances
...
name = name

cod

def bark(self):
# Instance method
print(f"{self
...
Use @classmethod
...
species}")

Static Methods


Do not depend on instance or class attributes
...


class Utility:
@staticmethod

def add(a, b):
return a + b
print(Utility
...
Inheritance
Basic Inheritance


Allows one class to inherit the attributes and methods of another class
...
name = name

De

def speak(self):
print(f"{self
...
")

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class Dog(Animal):
# Dog inherits from Animal
def speak(self):
print(f"{self
...
")
dog = Dog("Buddy")
dog
...

super()


Function

Calls the parent class's methods
...
__init__(name)
# Call parent class constructor
self
...
Encapsulation
Public, Protected, and Private Attributes


Public Attributes: Accessible anywhere
...
brand = brand # Public attribute



Protected Attributes: Indicated by a single underscore _, meant for internal use, but
still accessible
...
_brand = brand # Protected attribute



Private Attributes: Indicated by double underscore __, not accessible directly
...
__brand = brand # Private attribute

Accessing Private Attributes (Name Mangling)
car = Car("Tesla")
print(car
...
Polymorphism

De

Method Overriding


Redefining a method in a derived class that exists in the parent class
...
14 * self
...
Focuses on methods rather than inheritance
...
sound()
animal_sound(Dog())
animal_sound(Cat())

# Output: Bark
# Output: Meow

7
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Use abc module to define abstract classes
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sound()

# Must implement abstract method
# Output: Bark

8
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method_a()
obj
...
FUNCTIONS
Defining a Function
Basic Syntax
def function_name(parameters):
# function body
return result

Example
def greet(name):
return f"Hello, {name}!"
print(greet("Alice"))

# Output: Hello, Alice!

2
...


def add(a, b):
return a + b
add(2, 3)

# Output: 5

Keyword Arguments


Passed by name during function call
...
"

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describe(age=25, name="Alice")

# Output: Alice is 25 years old
...


def greet(name, message="Hello"):
return f"{message}, {name}!"
greet("Alice")
greet("Alice", "Hi")

cod

# Output: Hello, Alice!
# Output: Hi, Alice!

3
...


def add(*args):
return sum(args)
add(1, 2, 3, 4)
**kwargs


# Output: 10

(Keyword Variable-Length)

Allows passing multiple keyword arguments
...
Scope

# Output: Hi, Bob!

es

Local Scope


Variables defined within a function are local to that function
...

# Global variable

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def my_func():
print(x) # Accessing global variable
my_func()

# Output: 20

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Using global Keyword


Modify global variables inside a function
...
Returning Values

cod

Returning a Single Value
def square(x):
return x ** 2
result = square(4)

# Output: 16

Returning Multiple Values
def coordinates():
return (1, 2, 3)
x, y, z = coordinates()

6
...


De

7
...


def add(*args):
return sum(args)
print(add(1, 2, 3))

# Output: 6

Using **kwargs


cod

Accepts a variable number of keyword arguments
...
items():
print(f"{key}: {value}")
greet(name="Alice", age=25)

es

# Output: name: Alice, age: 25

8
...


python
Copy code
list(map(lambda x: x * 2, [1, 2, 3]))


filter():

# Output: [2, 4, 6]

Filter items based on a condition
...


python
Copy code
sorted([3, 1, 2])

# Output: [1, 2, 3]

4
...
close()

2
...
Reading Files


Reading Entire File:

cod

with open("file
...
read()
print(content)


Reading Line by Line:
with open("file
...


with open("file
...
readline()
print(line)


readlines():

Returns a list of lines
...
txt", "r") as file:
lines = file
...
Writing Files


Writing with 'w' (Overwrites):
with open("file
...
write("Hello, world!")



Appending with 'a':
with open("file
...
write("\nAdding a new line
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File Object Methods

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




file
...

file
...

file
...

file
...


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6
...
bin", "wb") as file:
file
...
bin", "rb") as file:
data = file
...
Checking if File Exists


Using os module:
import os
if os
...
exists("file
...
Exception Handling
1
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Catching Multiple Exceptions


Using Multiple except Blocks:

De
try:

x = int(input("Enter a number: "))
y = 1 / x
except ValueError:
print("That's not a number!")
except ZeroDivisionError:
print("You cannot divide by zero!")



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Using Single except Block:
try:

cod

x = int(input("Enter a number: "))
y = 1 / x
except (ValueError, ZeroDivisionError) as e:
print(f"Error occurred: {e}")

3
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txt", "r")
# Some code that may raise an exception
except FileNotFoundError:
print("File not found")
finally:
file
...
Else Block


es

The finally block runs no matter what happens in the try block:

Runs if no exceptions occur:
try:
file = open("file
...
close()

5
...
Custom Exceptions


Creating a Custom Exception:
class MyError(Exception):
pass

De

def check_value(value):
if value < 0:
raise MyError("Value cannot be negative")
try:
check_value(-1)
except MyError as e:
print(e)

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Modules and Packages
1
...
Accessing Module Content


Calling functions from imported module:
python

es

Copy code
import math
result = math
...
0


Importing multiple functions:
python
Copy code
from math import sqrt, ceil
result = ceil(sqrt(10))



List of all functions and attributes of a module:
python
Copy code
import module_name
print(dir(module_name))

De

3
...
py file:
python
Copy code
# In my_module
...
greet("John")

4
...
py
module1
...
py



Importing a module from a package:
python
Copy code
from my_package import module1



Importing specific functions or classes:

es

python
Copy code
from my_package

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