Code-Memo

Basic Operations

Arithmetic Operations

• Addition: +
• Subtraction: -
• Multiplication: *
• Division: /
• Floor Division: //
• Modulus: %
• Exponentiation: **

a = 10
b = 3

print(a + b)  # 13
print(a - b)  # 7
print(a * b)  # 30
print(a / b)  # 3.3333333333333335
print(a // b) # 3
print(a % b)  # 1
print(a ** b) # 1000

Comparison Operators

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

a = 10
b = 20

print(a == b)  # False
print(a != b)  # True
print(a > b)   # False
print(a < b)   # True
print(a >= b)  # False
print(a <= b)  # True

Logical Operators

• and: and
• or: or
• not: not

x = True
y = False

print(x and y)  # False
print(x or y)   # True
print(not x)    # False

Assignment Operators

• Assign: =
• Add and assign: +=
• Subtract and assign: -=
• Multiply and assign: *=
• Divide and assign: /=
• Floor divide and assign: //=
• Modulus and assign: %=
• Exponent and assign: **=

a = 10
a += 5  # a = a + 5
print(a)  # 15

Variable Scope

• Local variables are defined within a function and can only be used there.
• Global variables are defined outside any function and can be accessed anywhere.

x = 5  # Global variable

def func():
    y = 10  # Local variable
    global x
    x = 20  # Modify global variable

func()
print(x)  # 20

Type Hinting

Python supports type hints to specify the expected type of variables.

def greeting(name: str) -> str:
    return "Hello, " + name

name: str = "Alice"
age: int = 30

F-Strings

Formatted string literals for easy string interpolation.

name = "Alice"
age = 30

print(f"Hello, {name}. You are {age} years old.")

Lambda Functions

Small anonymous functions.

add = lambda x, y: x + y
print(add(2, 3))  # 5

Unpacking

Extracting values from collections.

a, b, c = (1, 2, 3)
print(a, b, c)  # 1 2 3

lst = [4, 5, 6]
x, y, z = lst
print(x, y, z)  # 4 5 6

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Using the enumerate function

Enumerate adds a counter to an iterable.

for index, value in enumerate(['a', 'b', 'c']):
    print(index, value)

Using the zip function

Combining iterables.

names = ["Alice", "Bob", "Charlie"]
ages = [25, 30, 35]

for name, age in zip(names, ages):
    print(f"{name} is {age} years old.")

Using the map function

Apply a function to all items in an input list.

nums = [1, 2, 3, 4, 5]
squares = list(map(lambda x: x**2, nums))
print(squares)  # [1, 4, 9, 16, 25]

Using the filter function

Filter items out of a list.

nums = [1, 2, 3, 4, 5]
even_nums = list(filter(lambda x: x % 2 == 0, nums))
print(even_nums)  # [2, 4]

Using the reduce function

Apply a function of two arguments cumulatively.

from functools import reduce

nums = [1, 2, 3, 4, 5]
product = reduce(lambda x, y: x * y, nums)
print(product)  # 120

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Ternary Conditional Operator

x = 10
result = "Greater than 5" if x > 5 else "5 or less"
print(result)

Custom Increments

x = 5
increment = 3
x += increment
print(x)  # 8

Using any() and all()

• any(): Returns True if any element in an iterable is True.

  conditions = [False, True, False]
  if any(conditions):
      print("At least one condition is true")
  

• all(): Returns True if all elements in an iterable are True.

  conditions = [True, True, True]
  if all(conditions):
      print("All conditions are true")