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README.md

Python 3 Keywords and Example Usage

1. False

is_sunny = False
print(is_sunny)  # Output: False

2. None

result = None
print(result)  # Output: None

3. True

is_sunny = True
print(is_sunny)  # Output: True

4. and

x = 10
y = 5
if x > 5 and y < 10:
    print("Both conditions are true.")  # Output: Both conditions are true.

5. as

import datetime as dt
current_date = dt.date.today()
print(current_date)

6. assert

age = 25
assert age >= 18, "Age must be at least 18."

7. async (Python 3.5+)

import asyncio

async def main():
    print('Hello ...')
    await asyncio.sleep(1)
    print('... World!')

asyncio.run(main())

8. await (Python 3.5+)

import asyncio

async def say_hello():
    await asyncio.sleep(1)
    print("Hello")

asyncio.run(say_hello())

9. break

for i in range(5):
    if i == 3:
        break
    print(i)  # Output: 0 1 2

10. class

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

obj = MyClass("Python")
print(obj.name)  # Output: Python

11. continue

for i in range(5):
    if i == 3:
        continue
    print(i)  # Output: 0 1 2 4

12. def

def greet():
    print("Hello, World!")

greet()

13. del

x = [1, 2, 3]
del x[1]
print(x)  # Output: [1, 3]

14. elif

x = 5
if x > 10:
    print("Greater than 10")
elif x > 5:
    print("Greater than 5")
else:
    print("5 or less")  # Output: 5 or less

15. else

x = 5
if x > 10:
    print("Greater than 10")
else:
    print("10 or less")  # Output: 10 or less

16. except

try:
    x = 1 / 0
except ZeroDivisionError:
    print("Cannot divide by zero")  # Output: Cannot divide by zero

17. finally

try:
    x = 1 / 0
except ZeroDivisionError:
    print("Cannot divide by zero")
finally:
    print("This is executed no matter what")  # Output: This is executed no matter what

18. for

for i in range(3):
    print(i)  # Output: 0 1 2

19. from

from math import sqrt
print(sqrt(16))  # Output: 4.0

20. global

x = 5
def set_global_x():
    global x
    x = 10

set_global_x()
print(x)  # Output: 10

21. if

x = 5
if x > 0:
    print("Positive number")  # Output: Positive number

22. import

import math
print(math.pi)  # Output: 3.141592653589793

23. in

fruits = ["apple", "banana", "cherry"]
if "banana" in fruits:
    print("Banana is in the list")  # Output: Banana is in the list

24. is

x = [1, 2, 3]
y = x
print(x is y)  # Output: True

25. lambda

add = lambda a, b: a + b
print(add(2, 3))  # Output: 5

26. nonlocal

def outer():
    x = "outer"
    def inner():
        nonlocal x
        x = "inner"
    inner()
    print(x)  # Output: inner

outer()

27. not

x = False
if not x:
    print("x is False")  # Output: x is False

28. or

x = 5
y = 10
if x > 0 or y > 0:
    print("At least one is positive")  # Output: At least one is positive

29. pass

def func():
    pass

30. raise

def check_positive(x):
    if x < 0:
        raise ValueError("x must be positive")
    return x

check_positive(-1)

31. return

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

print(add(2, 3))  # Output: 5

32. try

try:
    x = int("invalid")
except ValueError:
    print("Invalid value")  # Output: Invalid value

33. while

i = 0
while i < 3:
    print(i)  # Output: 0 1 2
    i += 1

34. with

with open("test.txt", "w") as file:
    file.write("Hello, World!")

35. yield

def generator():
    yield 1
    yield 2
    yield 3

for value in generator():
    print(value)  # Output: 1 2 3

Python Built-in Functions and Example Usage

Type Conversion Functions

  • int()
num_str = "42"
num_int = int(num_str)
print(num_int)  # Output: 42
  • float()
num_str = "3.14"
num_float = float(num_str)
print(num_float)  # Output: 3.14
  • str()
num_int = 42
num_str = str(num_int)
print(num_str)  # Output: "42"
  • list()
num_tuple = (1, 2, 3)
num_list = list(num_tuple)
print(num_list)  # Output: [1, 2, 3]
  • tuple()
num_list = [1, 2, 3]
num_tuple = tuple(num_list)
print(num_tuple)  # Output: (1, 2, 3)
  • dict()
pairs = [("a", 1), ("b", 2), ("c", 3)]
num_dict = dict(pairs)
print(num_dict)  # Output: {'a': 1, 'b': 2, 'c': 3}
  • set()
num_list = [1, 2, 2, 3, 3, 3]
num_set = set(num_list)
print(num_set)  # Output: {1, 2, 3}
  • bool()
is_true = bool(1)
is_false = bool(0)
print(is_true)   # Output: True
print(is_false)  # Output: False
  • complex()
complex_num = complex(2, 3)
print(complex_num)  # Output: (2+3j)
  • chr()
char_code = chr(65)
print(char_code)  # Output: 'A'
  • ord()
char_code = ord('A')
print(char_code)  # Output: 65

Mathematical Functions

  • abs()
abs_value = abs(-5)
print(abs_value)  # Output: 5
  • round()
rounded_num = round(3.14159, 2)
print(rounded_num)  # Output: 3.14
  • pow()
result = pow(2, 3)
print(result)  # Output: 8
  • max()
max_num = max(1

, 5, 3)
print(max_num)  # Output: 5
  • min()
min_num = min(1, 5, 3)
print(min_num)  # Output: 1
  • sum()
numbers = [1, 2, 3, 4, 5]
sum_result = sum(numbers)
print(sum_result)  # Output: 15
  • divmod()
quotient, remainder = divmod(10, 3)
print(quotient, remainder)  # Output: 3 1

Iterable Functions

  • len()
str_len = len("Hello")
print(str_len)  # Output: 5
  • range()
numbers = list(range(1, 6))
print(numbers)  # Output: [1, 2, 3, 4, 5]
  • enumerate()
fruits = ['apple', 'banana', 'cherry']
for index, fruit in enumerate(fruits):
    print(index, fruit)
# Output:
# 0 apple
# 1 banana
# 2 cherry
  • zip()
names = ['John', 'Jane', 'Jim']
ages = [25, 30, 22]
for name, age in zip(names, ages):
    print(name, age)
# Output:
# John 25
# Jane 30
# Jim 22
  • sorted()
numbers = [3, 1, 4, 1, 5, 9, 2]
sorted_numbers = sorted(numbers)
print(sorted_numbers)  # Output: [1, 1, 2, 3, 4, 5, 9]
  • reversed()
numbers = [1, 2, 3, 4, 5]
reversed_numbers = list(reversed(numbers))
print(reversed_numbers)  # Output: [5, 4, 3, 2, 1]
  • all()
values = [True, False, True]
print(all(values))  # Output: False (since one value is False)
  • any()
values = [False, False, True]
print(any(values))  # Output: True (since one value is True)

Input/Output Functions

  • print()
print("Hello, World!")
  • input()
name = input("Enter your name: ")
print("Hello, " + name)

Object Type Functions

  • type()
x = 5
print(type(x))  # Output: <class 'int'>
  • id()
x = 5
print(id(x))  # Output: (some memory address)
  • isinstance()
x = 5
print(isinstance(x, int))  # Output: True

String Functions

  • str()
num_int = 42
num_str = str(num_int)
print(num_str)  # Output: "42"
  • len()
str_len = len("Hello")
print(str_len)  # Output: 5
  • ord()
char_code = ord('A')
print(char_code)  # Output: 65
  • chr()
char_code = chr(65)
print(char_code)  # Output: 'A'
  • capitalize()
text = "hello, world"
capitalized_text = text.capitalize()
print(capitalized_text)  # Output: "Hello, world"
  • upper()
text = "hello, world"
upper_case_text = text.upper()
print(upper_case_text)  # Output: "HELLO, WORLD"
  • lower()
text = "Hello, World"
lower_case_text = text.lower()
print(lower_case_text)  # Output: "hello, world"
  • strip()
text = "   hello, world   "
stripped_text = text.strip()
print(stripped_text)  # Output: "hello, world"
  • split()
text = "apple,banana,orange"
fruits = text.split(",")
print(fruits)  # Output: ['apple', 'banana', 'orange']
  • join()
fruits = ['apple', 'banana', 'orange']
text = ", ".join(fruits)
print(text)  # Output: "apple, banana, orange"
  • format()
name = "John"
age = 30
formatted_text = "My name is {} and I am {} years old.".format(name, age)
print(formatted_text)
# Output: "My name is John and I am 30 years old."

List Functions

  • list()
num_tuple = (1, 2, 3)
num_list = list(num_tuple)
print(num_list)  # Output: [1, 2, 3]
  • len()
str_len = len("Hello")
print(str_len)  # Output: 5
  • max()
max_num = max([1, 2, 3, 4, 5])
print(max_num)  # Output: 5
  • min()
min_num = min([1, 2, 3, 4, 5])
print(min_num)  # Output: 1
  • sum()
numbers = [1, 2, 3, 4, 5]
sum_result = sum(numbers)
print(sum_result)  # Output: 15
  • append()
numbers = [1, 2, 3]
numbers.append(4)
print(numbers)  # Output: [1, 2, 3, 4]
  • extend()
numbers = [1, 2, 3]
new_numbers = [4, 5]
numbers.extend(new_numbers)
print(numbers)  # Output: [1, 2, 3, 4, 5]
  • pop()
numbers = [1, 2, 3, 4, 5]
popped_item = numbers.pop()
print(popped_item)  # Output: 5
print(numbers)     # Output: [1, 2, 3, 4]
  • remove()
numbers = [1, 2, 3, 4, 5]
numbers.remove(3)
print(numbers)  # Output: [1, 2, 4, 5]
  • count()
numbers = [1, 2, 2, 3, 3, 3]
count_2 = numbers.count(2)
print(count_2)  # Output: 2
  • index()
numbers = [1, 2, 3, 4, 5]
index_3 = numbers.index(3)
print(index_3)  # Output: 2 (index of the first occurrence of 3)
  • sort()
numbers = [3, 1, 4, 1, 5, 9, 2]
numbers.sort()
print(numbers)  # Output: [1, 1, 2, 3, 4, 5, 9]
  • reverse()
numbers = [1, 2, 3, 4, 5]
numbers.reverse()
print(numbers)  # Output: [5, 4, 3, 2, 1]

Tuple Functions

  • tuple()
num_list = [1, 2, 3]
num_tuple = tuple(num_list)
print(num_tuple)  # Output: (1, 2, 3)
  • len()
str_len = len("Hello")
print(str_len)  # Output: 5
  • max()
max_num = max((1, 2, 3, 4, 5))
print(max_num)  # Output: 5
  • min()
min_num = min((1, 2, 3, 4, 5))
print(min_num)  # Output: 1
  • sum()
numbers = (1, 2, 3, 4, 5)
sum_result = sum(numbers)
print(sum_result)  # Output: 15
  • count()
numbers = (1, 2, 2, 3, 3, 3)
count_2 = numbers.count(2)
print(count_2)  # Output: 2
  • index()
numbers = (1, 2, 3, 4, 5)
index_3 = numbers.index(3)
print(index_3)  # Output: 2 (index of the first occurrence

 of 3)

Dictionary Functions

  • dict()
pairs = [("a", 1), ("b", 2), ("c", 3)]
num_dict = dict(pairs)
print(num_dict)  # Output: {'a': 1, 'b': 2, 'c': 3}
  • len()
str_len = len("Hello")
print(str_len)  # Output: 5
  • keys()
person = {'name': 'John', 'age': 30, 'city': 'New York'}
keys = person.keys()
print(keys)  # Output: dict_keys(['name', 'age', 'city'])
  • values()
person = {'name': 'John', 'age': 30, 'city': 'New York'}
values = person.values()
print(values)  # Output: dict_values(['John', 30, 'New York'])
  • items()
person = {'name': 'John', 'age': 30, 'city': 'New York'}
items = person.items()
print(items)
# Output: dict_items([('name', 'John'), ('age', 30), ('city', 'New York')])
  • get()
person = {'name': 'John', 'age': 30}
name = person.get('name')
print(name)  # Output: 'John'
  • pop()
person = {'name': 'John', 'age': 30}
age = person.pop('age')
print(age)  # Output: 30
  • popitem()
person = {'name': 'John', 'age': 30}
key, value = person.popitem()
print(key, value)  # Output: 'age' 30
  • update()
person = {'name': 'John', 'age': 30}
person.update({'city': 'New York'})
print(person)  # Output: {'name': 'John', 'age': 30, 'city': 'New York'}
  • clear()
person = {'name': 'John', 'age': 30}
person.clear()
print(person)  # Output: {}

Set Functions

  • set()
num_list = [1, 2, 2, 3, 3, 3]
num_set = set(num_list)
print(num_set)  # Output: {1, 2, 3}
  • len()
str_len = len("Hello")
print(str_len)  # Output: 5
  • add()
fruits = {'apple', 'banana', 'orange'}
fruits.add('mango')
print(fruits)  # Output: {'apple', 'banana', 'orange', 'mango'}
  • remove()
fruits = {'apple', 'banana', 'orange'}
fruits.remove('banana')
print(fruits)  # Output: {'apple', 'orange'}
  • discard()
fruits = {'apple', 'banana', 'orange'}
fruits.discard('banana')
print(fruits)  # Output: {'apple', 'orange'}
  • pop()
fruits = {'apple', 'banana', 'orange'}
removed_fruit = fruits.pop()
print(removed_fruit)  # Output: (any of the fruits in the set)
  • clear()
fruits = {'apple', 'banana', 'orange'}
fruits.clear()
print(fruits)  # Output: set()
  • union()
set1 = {1, 2, 3}
set2 = {3, 4, 5}
union_set = set1.union(set2)
print(union_set)  # Output: {1, 2, 3, 4, 5}
  • intersection()
set1 = {1, 2, 3}
set2 = {3, 4, 5}
intersection_set = set1.intersection(set2)
print(intersection_set)  # Output: {3}
  • difference()
set1 = {1, 2, 3}
set2 = {3, 4, 5}
difference_set = set1.difference(set2)
print(difference_set)  # Output: {1, 2}
  • issubset()
set1 = {1, 2, 3}
set2 = {1, 2, 3, 4, 5}
is_subset = set1.issubset(set2)
print(is_subset)  # Output: True
  • issuperset()
set1 = {1, 2, 3, 4, 5}
set2 = {1, 2, 3}
is_superset = set1.issuperset(set2)
print(is_superset)  # Output: True

Miscellaneous Functions

  • input()
name = input("Enter your name: ")
print("Hello, " + name)
  • abs()
abs_value = abs(-5)
print(abs_value)  # Output: 5
  • pow()
result = pow(2, 3)
print(result)  # Output: 8
  • open()
with open("myfile.txt", "w") as file:
    file.write("Hello, World!")
  • sorted()
numbers = [3, 1, 4, 1, 5, 9, 2]
sorted_numbers = sorted(numbers)
print(sorted_numbers)  # Output: [1, 1, 2, 3, 4, 5, 9]
  • range()
numbers = list(range(1, 6))
print(numbers)  # Output: [1, 2, 3, 4, 5]
  • id()
x = 5
print(id(x))  # Output: (some memory address)
  • format()
name = "John"
age = 30
formatted_text = "My name is {} and I am {} years old.".format(name, age)
print(formatted_text)
# Output: "My name is John and I am 30 years old."
  • help()
help(list)
# Output: (Help documentation for the list type)

Operators

1. Arithmetic Operators:

  • +: Addition
  • -: Subtraction
  • *: Multiplication
  • /: Division (float)
  • //: Division (integer)
  • %: Modulus (remainder)
  • **: Exponentiation

2. Assignment Operators:

  • =: Assign value
  • +=: Add and assign
  • -=: Subtract and assign
  • *=: Multiply and assign
  • /=: Divide and assign
  • //=: Divide and assign (integer)
  • %=: Modulus and assign
  • **=: Exponentiate and assign

3. Comparison Operators:

  • ==: Equal to
  • !=: Not equal to
  • <: Less than
  • >: Greater than
  • <=: Less than or equal to
  • >=: Greater than or equal to

4. Logical Operators:

  • and: Logical AND
  • or: Logical OR
  • not: Logical NOT

5. Bitwise Operators:

  • &: Bitwise AND
  • |: Bitwise OR
  • ^: Bitwise XOR
  • ~: Bitwise NOT
  • <<: Left shift
  • >>: Right shift

6. Identity Operators:

  • is: Returns True if both variables are the same object
  • is not: Returns True if both variables are not the same object

7. Membership Operators:

  • in: Returns True if a sequence with the specified value is present
  • not in: Returns True if a sequence with the specified value is not present

8. Ternary Operator (Conditional Expression):

  • expression1 if condition else expression2: Returns expression1 if condition is true; otherwise, it returns expression2

Example Usage of Operators

1. Arithmetic Operators:

a = 5
b = 3

# Addition
result = a + b
print("Addition:", result)  # Output: 8

# Subtraction
result = a - b
print("Subtraction:", result)  # Output: 2

# Multiplication
result = a * b
print("Multiplication:", result)  # Output: 15

# Division (float)
result = a / b
print("Division (float):", result)  # Output: 1.6666666666666667

# Division (integer)
result = a // b
print("Division (integer):", result)  # Output: 1

# Modulus (remainder)
result = a % b
print("Modulus:", result)  # Output: 2

# Exponent

iation
result = a ** b
print("Exponentiation:", result)  # Output: 125

2. Assignment Operators:

x = 10

# Add and assign
x += 5
print("Add and assign:", x)  # Output: 15

# Subtract and assign
x -= 3
print("Subtract and assign:", x)  # Output: 12

# Multiply and assign
x *= 2
print("Multiply and assign:", x)  # Output: 24

# Divide and assign
x /= 4
print("Divide and assign:", x)  # Output: 6.0

# Divide and assign (integer)
x //= 2
print("Divide and assign (integer):", x)  # Output: 3.0

# Modulus and assign
x %= 2
print("Modulus and assign:", x)  # Output: 1.0

# Exponentiate and assign
x **= 3
print("Exponentiate and assign:", x)  # Output: 1.0

3. Comparison Operators:

a = 5
b = 10

# Equal to
print("Equal to:", a == b)  # Output: False

# Not equal to
print("Not equal to:", a != b)  # Output: True

# Less than
print("Less than:", a < b)  # Output: True

# Greater than
print("Greater than:", a > b)  # Output: False

# Less than or equal to
print("Less than or equal to:", a <= b)  # Output: True

# Greater than or equal to
print("Greater than or equal to:", a >= b)  # Output: False

4. Logical Operators:

x = True
y = False

# Logical AND
print("Logical AND:", x and y)  # Output: False

# Logical OR
print("Logical OR:", x or y)  # Output: True

# Logical NOT
print("Logical NOT (x):", not x)  # Output: False
print("Logical NOT (y):", not y)  # Output: True

5. Bitwise Operators:

a = 5   # Binary: 0101
b = 3   # Binary: 0011

# Bitwise AND
print("Bitwise AND:", a & b)  # Output: 1 (Binary: 0001)

# Bitwise OR
print("Bitwise OR:", a | b)  # Output: 7 (Binary: 0111)

# Bitwise XOR
print("Bitwise XOR:", a ^ b)  # Output: 6 (Binary: 0110)

# Bitwise NOT
print("Bitwise NOT (a):", ~a)  # Output: -6 (Binary: 11111111111111111111111111111010)

# Left shift
print("Left shift:", a << 1)  # Output: 10 (Binary: 1010)

# Right shift
print("Right shift:", a >> 1)  # Output: 2 (Binary: 0010)

6. Identity Operators:

a = [1, 2, 3]
b = a
c = [1, 2, 3]

# is
print("is (a and b):", a is b)  # Output: True
print("is (a and c):", a is c)  # Output: False

# is not
print("is not (a and b):", a is not b)  # Output: False
print("is not (a and c):", a is not c)  # Output: True

7. Membership Operators:

fruits = ["apple", "banana", "orange"]

# in
print("in:", "banana" in fruits)  # Output: True
print("in:", "grape" in fruits)  # Output: False

# not in
print("not in:", "banana" not in fruits)  # Output: False
print("not in:", "grape" not in fruits)  # Output: True

8. Ternary Operator (Conditional Expression):

age = 25

# Ternary operator
message = "You are an adult." if age >= 18 else "You are a minor."
print("Ternary Operator:", message)  # Output: "You are an adult."

Data Types in Python

1. Numeric Types:

  • int: Integer data type (e.g., 1, -10, 100)
  • float: Floating-point data type (e.g., 3.14, -0.5, 2.0)

2. Sequence Types:

  • str: String data type (e.g., "Hello", 'Python', "123")
  • list: List data type (e.g., [1, 2, 3], ['apple', 'banana'])
  • tuple: Tuple data type (e.g., (1, 2, 3), ('a', 'b', 'c'))

3. Mapping Type:

  • dict: Dictionary data type (e.g., {'key': 'value'}, {1: 'one', 2: 'two'})

4. Set Types:

  • set: Set data type (e.g., {1, 2, 3}, {'apple', 'banana'})

5. Boolean Type:

  • bool: Boolean data type (e.g., True, False)

6. None Type:

  • None: Represents the absence of a value (similar to null in other languages)

Example Usage of Data Types

1. Numeric Types:

# Integer data type
age = 25
print("Age:", age)

# Floating-point data type
pi = 3.14159
print("Pi:", pi)

2. Sequence Types:

# String data type
name = "John Doe"
print("Name:", name)

# List data type
numbers = [1, 2, 3, 4, 5]
print("Numbers:", numbers)

# Tuple data type
coordinates = (10, 20)
print("Coordinates:", coordinates)

3. Mapping Type:

# Dictionary data type
person = {'name': 'John', 'age': 30, 'city': 'New York'}
print("Person:", person)

4. Set Type:

# Set data type
fruits = {'apple', 'banana', 'orange'}
print("Fruits:", fruits)

5. Boolean Type:

# Boolean data type
is_sunny = True
is_raining = False
print("Is it sunny?", is_sunny)
print("Is it raining?", is_raining)

6. None Type:

# None data type
result = None
print("Result:", result)

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