Python

Python

• Python 2 is no longer supported (as of January 1, 2020)
• Python 3 is the latest version (as of 2023)
• Python 3 is the recommended version for new projects

create python virtual environemnt

python3 -m venv env
source env/bin/activate

install packages

pip install -r requirements.txt
pip freeze > requirements.txt

Python Basics

False, True, no x++, use x += 1

• .py file extension
• Indentation is significant (4 spaces or 1 tab)
• Use # for comments
• Use """ for docstrings
• Use __init__ for constructors
• Use __str__ for string representation
• Use __repr__ for official string representation
• Use __name__ for module name
• Use __main__ for main module
• to exit, use exit() or quit()
• input() to pause the program and wait for user input
• print() to print to the console
• if you mix space and tab, you will get an IndentationError

Reserved Keywords

Keyword	Keyword	Keyword	Keyword
False	None	True	and
as	assert	async	await
break	class	continue	def
del	elif	else	except
finally	for	from	global
if	import	in	is
lambda	nonlocal	not	or
pass	raise	return	try
while	with	yield

DataType Declaration

Although Python is dynamically typed, you can use type hints to indicate the expected type of a variable.

a: int = 5
b: float = 5.0
c: str = "Hello"
d: bool = True
e: list = [1, 2, 3]
f: tuple = (1, 2, 3)
g: dict = {"key": "value"}
h: set = {1, 2, 3}

# function with type hints
def add(a: int, b: int) -> int:
    return a + b