Indroduction

" Python is a high level, interepted programming language that was created by Guido van Rossum in 1991. It is well-known for its simplicity, readbility and versatile. the python is very clean and easy to understand, making it an excellent choice for beginners in programming language."

Basic

name = Sujit Tomar
print(name)
#Sujit Tomar

Some error Identify in python

Right Code in Normal Case

>>> print ("Sujit")
Sujit

>>> 500 * 2
1000

Variable Case Error

>>> Programming 
Traceback (most recent call last):
  File "<python-input-0>", line 1, in <module>
    Programming
NameError: name 'Programming' is not defined. Did you mean: 'quit'?

It means not variable define

Module Library or Packages Case Error

>>> import os
>>> os.getcwd()  
'C:\\Users\\PC\\OneDrive\\Documents\\Python'

>>> import abcfgf
Traceback (most recent call last):
  File "<python-input-4>", line 1, in <module>
    import abcfgf
ModuleNotFoundError: No module named 'abcfgf'

Remember cdw Means :- Current Working Directory

ModuleNotFoundError: it means when you write wrong name of library or module then show this type error

Syntax Case Error

>>> for s in "Sujit":
...     print(s)
... 
S
u
j
i
t
>>> 

<-------------------------------------------------->

>>> for s in "Sujit"
  File "<python-input-6>", line 1
    for s in "Sujit"
                    ^
SyntaxError: expected ':'

<-------------------------------------------------->

>>> for s in "Sujit":
... print(s)
... 
  File "<python-input-0>", line 2
    print(s)
    ^^^^^
IndentationError: expected an indented block after 'for' statement on line 1
>>> 
>>> 

it means you write wrong syntax in python

First you missed (:) because in for loop it is mandatory and Second you miss space (IndentationError) that is error

>>> import sys
>>> sys.platform()
Traceback (most recent call last):
  File "<python-input-3>", line 1, in <module>
    sys.platform()
    ~~~~~~~~~~~~^^
TypeError: 'str' object is not callable
>>> 
>>> import sys
>>> sys.platform
'win32'
>>> 

TypeError: 'str' object is not callable :- Means it is not a function

import updated

"When you import allrady any page to another page then use below syntax for update"

>>> from importlib import reload
>>> reload(page)

Data Type

Data Type	Discripition	Type	Example
Integers		Immutable	x= 5, y = 10
Floting Point Numbers		Immutable	a = 3.14, b = 5.36
Booliean		Immutable	is_active = True, isCompleted = False
String		Immutable	name = 'Sujit', fname = "bob's"
Tuples		Immutable	cordinates = (10, 20)
Frozen set		Immutable	frozen_set_example = frozenset([1, 2,3])
Bytes		Immutable	bytes_example = b"Sujit Tomar"
List		Mutable	num = [, 2, 3]
Set		Mutable	num = {1, 2, 3}
Dictionary		Mutable	stu = {"name" = "Sujit", "age" = 22}
Bitearray		Mutable	value = bytearray([65, 66, 67])
Array	it is contain same type value	Mutable	int_array = arrar.array("i", [1, 2, 3])

Comments in Python

# this is comments

Tips & Tricks

Use ** for for Exponentiation (Power Calculation):

# Squaring a number
square = 5 ** 2  # Output: 25

# Cubing a number
cube = 3 ** 3  # Output: 27

# Power of any number
result = 2 ** 5  # Output: 32

Swapping Two Variables Without a Temporary Variable:

a = 5
b = 10

# Swap values
a, b = b, a

print(a)  # Output: 10
print(b)  # Output: 5

List Comprehension :

# Create a list of squares from 0 to 9
squares = [x ** 2 for x in range(10)]
print(squares)  # Output: [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

# Filter even numbers from a list
even_numbers = [x for x in range(20) if x % 2 == 0]
print(even_numbers)  # Output: [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]

Unpacking Elements in a List:

numbers = [1, 2, 3, 4]

# Unpack into variables
a, b, c, d = numbers
print(a, b, c, d)  # Output: 1 2 3 4

# Unpacking with *
a, *b, c = numbers
print(a, b, c)  # Output: 1 [2, 3] 4

Using enumerate() for Index and Value:

fruits = ['apple', 'banana', 'cherry']

for index, fruit in enumerate(fruits):
    print(index, fruit)
# Output:
# 0 apple
# 1 banana
# 2 cherry

Using zip() for Parallel Iteration:

names = ['Alice', 'Bob', 'Charlie']
scores = [85, 90, 95]

for name, score in zip(names, scores):
    print(f'{name}: {score}')
# Output:
# Alice: 85
# Bob: 90
# Charlie: 95

Ternary Conditional Expression:

# Conditional assignment
x = 10
y = 20
max_value = x if x > y else y
print(max_value)  # Output: 20

Using set() for Removing Duplicates from a List:

numbers = [1, 2, 2, 3, 4, 4, 5]
unique_numbers = list(set(numbers))
print(unique_numbers)  # Output: [1, 2, 3, 4, 5]

Reversing a String or List:

# Reverse a string
text = "hello"
reversed_text = text[::-1]
print(reversed_text)  # Output: "olleh"

# Reverse a list
my_list = [1, 2, 3, 4, 5]
reversed_list = my_list[::-1]
print(reversed_list)  # Output: [5, 4, 3, 2, 1]

Reversing a String or List:

# Reverse a string
text = "hello"
reversed_text = text[::-1]
print(reversed_text)  # Output: "olleh"

# Reverse a list
my_list = [1, 2, 3, 4, 5]
reversed_list = my_list[::-1]
print(reversed_list)  # Output: [5, 4, 3, 2, 1]

Using _ in the REPL to Access the Last Result:

>>> 10 + 5
15
>>> _ * 2
30

Chaining Comparison Operators:

# Check if a number is between 10 and 20
x = 15
print(10 < x < 20)  # Output: True

Merging Two Dictionaries (Python 3.9+):

dict1 = {'a': 1, 'b': 2}
dict2 = {'c': 3, 'd': 4}

merged_dict = dict1 | dict2
print(merged_dict)  # Output: {'a': 1, 'b': 2, 'c': 3, 'd': 4}

Using any() and all() for Logical Checks:

# Check if any number is positive
numbers = [-1, -2, 3, -4]
print(any(n > 0 for n in numbers))  # Output: True

# Check if all numbers are positive
print(all(n > 0 for n in numbers))  # Output: False

Sorting a List of Dictionaries by Key:

students = [
    {'name': 'Alice', 'grade': 90},
    {'name': 'Bob', 'grade': 85},
    {'name': 'Charlie', 'grade': 95}
]

# Sort by 'grade'
sorted_students = sorted(students, key=lambda student: student['grade'])
print(sorted_students)
# Output: [{'name': 'Bob', 'grade': 85}, {'name': 'Alice', 'grade': 90}, {'name': 'Charlie', 'grade': 95}]

Using defaultdict to Avoid KeyErrors:

from collections import defaultdict

# Create a defaultdict with default type 'int'
my_dict = defaultdict(int)
my_dict['apple'] += 1

print(my_dict)  # Output: defaultdict(<class 'int'>, {'apple': 1})

Combining Multiple Strings:

words = ["Python", "is", "fun"]
sentence = " ".join(words)
print(sentence)  # Output: Python is fun

Lambda Functions:

# A simple lambda function to calculate square
square = lambda x: x ** 2
print(square(5))  # Output: 25

# Using lambda with `map`
numbers = [1, 2, 3, 4]
squares = list(map(lambda x: x ** 2, numbers))
print(squares)  # Output: [1, 4, 9, 16]

Using Counter to Count Elements in a List:

from collections import Counter

elements = ['a', 'b', 'a', 'c', 'b', 'a']
counter = Counter(elements)
print(counter)  # Output: Counter({'a': 3, 'b': 2, 'c': 1})

Dictionary Comprehension:

# Example: Create a dictionary of squares
squares_dict = {x: x ** 2 for x in range(6)}
print(squares_dict)  # Output: {0: 0, 1: 1, 2: 4, 3: 9, 4: 16, 5: 25}

Using get() to Access Dictionary Values Safely:

my_dict = {'a': 1, 'b': 2}

# Access an existing key
print(my_dict.get('a'))  # Output: 1

# Access a non-existing key (returns None)
print(my_dict.get('c'))  # Output: None

# Providing a default value
print(my_dict.get('c', 0))  # Output: 0

math :

>>> import math
>>> math.pi
3.141592653589793
>>> 

Random :

>>> import random
>>> random.random()
0.4596604027751191
>>> random.random()
0.20735437958994385
>>> random.random()
0.39390716757344313
>>> random.random()
0.9018445517995602
>>> 

>>> random.choice([1, 2, 3, 4, 5])
3
>>> random.choice([1, 2, 3, 4, 5])
4
>>> random.choice([1, 2, 3, 4, 5])
3
>>> 

Range :

>>> squar = [x**2 for x in range(10)]
>>> squar
[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

>>> cubeNum = [x**3 for x in range (10)]
>>> cubeNum
[0, 1, 8, 27, 64, 125, 216, 343, 512, 729]
>>>