Python Cheatsheet

https://github.com/wilfredinni/python-cheatsheet
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A Python cheatsheet providing basic references for beginner and advanced developers to lower the...
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### Setup and Contribute to Python Cheatsheet

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/src/pages/contributing.md

Steps to set up the Python cheatsheet project locally, including installing pnpm, cloning the repository, installing dependencies, creating a branch, making changes, and pushing them for a pull request.

```Shell
curl -fsSL https://get.pnpm.io/install.sh | sh -
```

```Shell
iwr https://get.pnpm.io/install.ps1 -useb | iex
```

```Shell
git clone https://github.com/wilfredinni/python-cheatsheet.git
cd python-cheatsheet
pnpm install
```

```Shell
git branch fix_bug
git checkout fix_bug
```

```Shell
git add .
git commit -m 'succinct explanation of what changed'
git push origin fix_bug
```

--------------------------------

### Initialize a new project interactively

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-projects-with-poetry-and-vscode-part-1.md

For existing projects, `poetry init` can be used to interactively create a `pyproject.toml` file, guiding the user through project metadata and dependency setup.

```shell
poetry init
```

--------------------------------

### Install Project Dependencies with Poetry

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/virtual-environments.md

Installs all dependencies listed in the `pyproject.toml` file for the current project. This command is used to set up the project environment after cloning or when starting work.

```Shell
poetry install
```

--------------------------------

### Interactive Python Shell Usage Example

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-projects-with-poetry-and-vscode-part-3.md

Demonstrates how to use the timer decorator in an interactive Python session after installing the package.

```python
>>> from how_long import timer
>>> 
>>> @timer
... def test_function():
...     [i for i in range(10000)]
... 
>>> test_function()
Execution Time: 705 ms.
```

--------------------------------

### Install Poetry with pip

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-projects-with-poetry-and-vscode-part-1.md

Installs the Poetry dependency management tool using pip. This is a quick way to get started, though the official installer is recommended for better isolation.

```shell
pip install poetry
```

--------------------------------

### Install Python Package with setup.py

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/setup-py.md

This command installs a Python package using its `setup.py` script. It's a common way to manage local installations or packages not yet published to PyPI. Ensure you are in the root directory of the package.

```bash
python setup.py install
```

--------------------------------

### Manage Tools with UVX and UV

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-uv-package-manager.md

Demonstrates running tools without explicit installation using `uvx` and installing tools globally with `uv tool install`.

```bash
# Run tools without installation
$ uvx ruff check

# Install tools globally
$ uv tool install ruff
```

--------------------------------

### Set Comprehension Example

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-comprehensions-step-by-step.md

Provides an example of creating a new set with uppercase elements from an existing set using a for loop, and then shows the equivalent, more concise set comprehension syntax.

```python
>>> my_set = {"abc", "def"}

>>> # Here, we create a new set with uppercase elements with a for loop
>>> new_set = set()
>>> for s in my_set:
...    new_set.add(s.upper())
>>> print(new_set)
# {'ABC', 'DEF'}
```

```python
>>> my_set = {"abc", "def"}
>>> new_set = {s.upper() for s in my_set}
>>> print(new_set)
# {'ABC', 'DEF'}
```

--------------------------------

### Python Tuple Use Cases

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-data-types.md

Provides examples of practical scenarios where tuples are beneficial, such as defining constants, representing fixed data like RGB colors, and using them as dictionary keys due to their immutability.

```python
# Good use cases
WINDOW_SIZE = (800, 600)        # Constants
DEFAULT_COLOR = (255, 255, 255) # RGB white

# Dictionary with tuple keys
locations = {
    (0, 0): "origin",
    (1, 1): "northeast",
    (-1, -1): "southwest"
}
```

--------------------------------

### Install Poetry with official installer

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-projects-with-poetry-and-vscode-part-1.md

Installs Poetry using its official installer script, which is the recommended method for isolating Poetry's dependencies from the system. This allows for easy updates via `poetry self update`.

```shell
curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/master/get-poetry.py | python -
```

--------------------------------

### Install Project Dependencies with Poetry

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-projects-with-poetry-and-vscode-part-1.md

Installs all packages defined in the pyproject.toml file, creating a virtual environment if one doesn't exist. This command is crucial after initializing a project or cloning a repository to set up the development environment.

```shell
$ poetry install
```

--------------------------------

### Python Project README Example

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-projects-with-poetry-and-vscode-part-3.md

Shows an example of a README file for a Python project, including a description and a code block demonstrating the usage of the `timer` decorator. This is typically written in reStructuredText (rst) format.

```rst
how_long
========

Simple Decorator to measure a function execution time.

Example
_______

.. code-block:: python

    from how_long import timer


    @timer
    def some_function():
        return [x for x in range(10_000_000)]
```

--------------------------------

### Install Anyconfig

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/json-yaml.md

Shows the bash command to install the `anyconfig` package, a utility for abstracting configuration file formats like JSON, YAML, and TOML.

```bash
pip install anyconfig
```

--------------------------------

### Python Numbers: int, float, complex Examples

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-data-types.md

Demonstrates the creation and basic usage of Python's integer (`int`), floating-point (`float`), and complex (`complex`) number types. It shows literal definitions and simple arithmetic operations, highlighting potential precision issues with floats.

```python
# Integers - whole numbers
age = 25
score = 100
negative = -10

# Floats - numbers with decimals
price = 19.99
temperature = 98.6
pi = 3.14159

# Complex - numbers with real and imaginary parts (advanced math)
z = 2 + 3j  # j represents the imaginary unit in Python

# Working with integers
items = 5
total_items = items * 3  # 15

# Working with floats
radius = 2.5
area = 3.14159 * radius * radius  # 19.634...

# Be careful with float precision
result = 0.1 + 0.2  # 0.30000000000000004 (not exactly 0.3!)

# Complex numbers (you probably won't need these as a beginner)
z = complex(2, 3)     # Same as 2+3j
magnitude = abs(z)    # 3.605...

```

--------------------------------

### Basic UV Package Management Commands

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-uv-package-manager.md

Demonstrates fundamental commands for managing Python packages using UV, including installing individual packages and installing from a requirements file.

```bash
# Install packages
$ uv pip install requests
```

```bash
# Install from requirements file
$ uv pip install -r requirements.txt
```

```bash
# List installed packages
$ uv pip list
```

--------------------------------

### Python help() function examples

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/builtin/help.md

Demonstrates how to use the Python `help()` built-in function to get documentation for various objects like types, classes, and the `help()` function itself. The output shown is typical for an interactive Python session.

```python
>>> help(type)
# Help on class type in module builtins:

# class type(object)
#  |  type(object_or_name, bases, dict)
#  |  type(object) -> the object's type
#  |  type(name, bases, dict) -> a new type
#  |
#  |  Methods defined here:
#  |
#  |  __call__(self, /, *args, **kwargs)
#  |      Call self as a function.
#  |
#  |  __delattr__(self, name, /)
#  |      Implement delattr(self, name).
#  |
#  |  __dir__(self, /)
#  |      Specialized __dir__ implementation for types.
#  |
#  |  __getattribute__(self, name, /)
# : 
```

```python
>>> help(str)
# Help on class str in module builtins:

# class str(object)
#  |  str(object='') -> str
#  |  str(bytes_or_buffer[, encoding[, errors]]) -> str
#  |
#  |  Create a new string object from the given object. If encoding or
#  |  errors is specified, then the object must expose a data buffer
#  |  that will be decoded using the given encoding and error handler.
#  |  Otherwise, returns the result of object.__str__() (if defined)
#  |  or repr(object).
#  |  encoding defaults to sys.getdefaultencoding().
#  |  errors defaults to 'strict'.
#  |
#  |  Methods defined here:
# : 
```

```python
>>> help(help)
# Help on _Helper in module _sitebuiltins object:

# class _Helper(builtins.object)
#  |  Define the builtin 'help'.
#  |
#  |  This is a wrapper around pydoc.help that provides a helpful message
#  |  when 'help' is typed at the Python interactive prompt.
#  |
#  |  Calling help() at the Python prompt starts an interactive help session.
#  |  Calling help(thing) prints help for the python object 'thing'.
#  |
#  |  Methods defined here:
#  |
#  |  __call__(self, *args, **kwds)
#  |      Call self as a function.
#  |
# : 
```

--------------------------------

### UV Python Version Management

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-uv-package-manager.md

Illustrates how to use UV to manage Python installations, specifically focusing on installing different Python versions.

```bash
# Install Python versions
$ uv python install 3.12
```

--------------------------------

### Install Ruamel.yaml

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/json-yaml.md

Provides the bash command to install the Ruamel.yaml library, which is recommended for better YAML specification compliance and comment preservation.

```bash
pip install ruamel.yaml
```

--------------------------------

### Install UV Package Manager

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-uv-package-manager.md

Provides instructions for installing UV using various methods, including shell scripts for Linux/macOS, PowerShell for Windows, and package managers like pip, pipx, and Homebrew.

```bash
# Using curl (Linux/macOS)
$ curl -LsSf https://astral.sh/uv/install.sh | sh
```

```powershell
# Using PowerShell (Windows)
$ powershell -c "irm https://astral.sh/uv/install.ps1 | iex"
```

```bash
# Using pip or pipx
$ pip install uv
$ pipx install uv
```

```bash
# Using Homebrew (macOS)
$ brew install uv
```

--------------------------------

### Install Poetry (Python Package Manager)

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/virtual-environments.md

Installs Poetry, a modern dependency management and packaging tool for Python. It helps declare project dependencies and manage them efficiently.

```Shell
pip install --user poetry
```

--------------------------------

### Python Number Formatting Examples

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/string-formatting.md

Demonstrates various Python number formatting techniques using f-strings for controlling decimal places, signs, padding, alignment, and separators. Includes examples for percentage and exponent notation.

```python
print(f"{{3.1415926:.2f}}")
# Output: 3.14
```

```python
print(f"{{-1:+.2f}}")
# Output: -1.00
```

```python
print(f"{{2.71828:.0f}}")
# Output: 3
```

```python
print(f"{{4:0>2d}}")
# Output: 04
```

```python
print(f"{{4:x<4d}}")
# Output: 4xxx
```

```python
print(f"{{10:x<4d}}")
# Output: 10xx
```

```python
print(f"{{1000000:,}}")
# Output: 1,000,000
```

```python
print(f"{{0.35:.2%}}")
# Output: 35.00%
```

```python
print(f"{{1000000000:.2e}}")
# Output: 1.00e+09
```

```python
print(f"{{11:11d}}")
# Output:          11
```

```python
print(f"{{11:<11d}}")
# Output: 11         
```

```python
print(f"{{11:^11d}}")
# Output:      11    
```

--------------------------------

### Basic Python setup.py Example

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/setup-py.md

A minimal `setup.py` file for a Python package. It defines essential metadata such as the package name, version, the Python packages to include, license, and a long description read from a README file. This script is used by Distutils to build and distribute the package.

```python
from distutils.core import setup

setup(
   name='pythonCheatsheet',
   version='0.1',
   packages=['pipenv',],
   license='MIT',
   long_description=open('README.txt').read(),
)
```

--------------------------------

### Get Relative Paths with os.path and pathlib

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/file-directory-path.md

Illustrates how to calculate the relative path from a starting directory to a target path. Examples include os.path.relpath() and Path.relative_to().

```python
>>> import os
>>> os.path.relpath('/etc/passwd', '/')
'etc/passwd'
```

```python
from pathlib import Path
print(Path('/etc/passwd').relative_to('/'))
# etc/passwd
```

--------------------------------

### Start New Project with UV

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-uv-package-manager.md

Steps to initialize a new Python project, add dependencies, and run commands within the project's isolated environment using `uv`.

```bash
# Initialize a new project
$ uv init example

# Navigate to project directory
$ cd example

# Add dependencies
$ uv add ruff

# Run commands in the project environment
$ uv run ruff check
```

--------------------------------

### Python itertools.count() Example

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/modules/itertools-module.md

Creates an iterator that returns evenly spaced values starting from a specified number. It accepts optional 'start' and 'step' arguments.

```python
>>> for i in itertools.count(10,3):
...     print(i)
...     if i > 20:
...         break
...
# 10
# 13
# 16
# 19
# 22
```

--------------------------------

### Get Relative Path

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/modules/pathlib-module.md

Illustrates how to obtain a relative path from a starting path to a target path using the `relative_to()` method. This is useful for expressing paths in a more concise way.

```python
from pathlib import Path

print(Path('/etc/passwd').relative_to('/'))
```

--------------------------------

### Python Dictionary Creation and Basic Access

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-data-types.md

Demonstrates how to create dictionaries using key-value pairs, access values by key, and use the .get() method for safer access, including providing default values.

```python
# Creating dictionaries
person = {"name": "Alice", "age": 30, "city": "New York"}
grades = {"math": 85, "english": 92, "science": 78}
empty = {}

# Accessing values
name = person["name"]        # "Alice"
age = person.get("age")      # 30 (safer way)
height = person.get("height", "unknown")  # "unknown" if key doesn't exist
```

--------------------------------

### Python Character Counting Example

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-data-types.md

Demonstrates how to count character occurrences in a string using a dictionary in Python. It iterates through the string, updating counts for each character.

```python
# Counting example
text = "hello world"
char_count = {}
for char in text:
    char_count[char] = char_count.get(char, 0) + 1
# Result: {'h': 1, 'e': 1, 'l': 3, 'o': 2, ' ': 1, 'w': 1, 'r': 1, 'd': 1}
```

--------------------------------

### Poetry Command Summary

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-projects-with-poetry-and-vscode-part-1.md

A reference table of common Poetry commands for project initialization, dependency management, and environment setup.

```APIDOC
Poetry Commands:

poetry new [package-name]
  - Description: Starts a new Python Project.

poetry init
  - Description: Creates a pyproject.toml file interactively.

poetry install
  - Description: Installs the packages inside the pyproject.toml file.

poetry add [package-name]
  - Description: Adds a package to a Virtual Environment.

poetry add -D [package-name]
  - Description: Adds a dev package to a Virtual Environment.

poetry remove [package-name]
  - Description: Removes a package from a Virtual Environment.

poetry remove -D [package-name]
  - Description: Removes a dev package from a Virtual Environment.

poetry self:update
  - Description: Updates poetry to the latest stable version.
```

--------------------------------

### Get Relative Path with os.path.relpath

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/modules/os-module.md

Shows how to compute a relative path from a starting directory to a target path using os.path.relpath(). This is useful for expressing paths concisely or when moving between directories.

```python
import os

print(os.path.relpath('/etc/passwd', '/'))
# 'etc/passwd'
```

--------------------------------

### UV Project Setup and Dependency Management

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/virtual-environments.md

Commands for initializing a new project with UV, adding dependencies, and running scripts within the project's environment.

```shell
uv init my-project
cd my-project
```

```shell
uv add requests
```

```shell
uv run python script.py
```

--------------------------------

### Python type() Examples

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/builtin/type.md

This snippet shows how to use the built-in Python `type()` function to get the type of different data types like strings, integers, floats, lists, tuples, sets, and dictionaries.

```python
>>> type('span')
# <class 'str'>
```

```python
>>> type(99)
# <class 'int'>
```

```python
>>> type(1.1)
# <class 'float'>
```

```python
>>> type([1, 2])
# <class 'list'>
```

```python
>>> type((1, 2))
# <class 'tuple'>
```

```python
>>> type({1, 2})
# <class 'set'>
```

```python
>>> type({'a': 1, 'b': 2})
# <class 'dict'>
```

--------------------------------

### Package Initialization and Version

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-projects-with-poetry-and-vscode-part-3.md

Defines the package's entry point by importing the timer decorator and sets the package version.

```python
from .how_long import timer

__version__ = "0.1.1"
```

--------------------------------

### Python sum() Function Examples

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/builtin/sum.md

Demonstrates the usage of Python's built-in sum() function to calculate the total of items in an iterable. The function takes an iterable of numbers and an optional start value, returning their sum.

```python
>>> sum([2, 4, 6])
# 12
>>> sum([10, 10, 10])
# 30
```

--------------------------------

### Python Set Creation and Initialization

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-data-types.md

Shows how to create sets in Python, including initializing with elements, creating an empty set using `set()`, and converting lists to sets to automatically remove duplicates.

```python
# Creating sets
colors = {"red", "green", "blue"}
numbers = {1, 2, 3, 4, 5}
empty = set()  # Note: {} creates an empty dict, not set!

# From lists (removes duplicates)
mixed_list = [1, 2, 2, 3, 3, 3]
unique_numbers = set(mixed_list)  # {1, 2, 3}
```

--------------------------------

### Python List Common Operations

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-data-types.md

Covers essential list manipulation techniques including adding items (append, insert, extend), removing items (remove, pop), and checking for item existence. Also shows how to get the length of a list.

```python
shopping_list = ["milk", "bread"]

# Adding items
shopping_list.append("eggs")         # ["milk", "bread", "eggs"]
shopping_list.insert(0, "butter")    # ["butter", "milk", "bread", "eggs"]
shopping_list.extend(["cheese", "ham"])  # Add multiple items

# Removing items
shopping_list.remove("milk")         # Remove first occurrence
last_item = shopping_list.pop()      # Remove and return last item
first_item = shopping_list.pop(0)    # Remove and return first item

# Useful operations
length = len(shopping_list)
has_bread = "bread" in shopping_list

# Processing lists
grades = [85, 92, 78, 96]
total = sum(grades)
average = total / len(grades)

for item in ["wash dishes", "walk dog", "study Python"]:
    print(f"Task: {item}")
```

--------------------------------

### Poetry Project Structure Example

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/virtual-environments.md

Illustrates the typical directory structure created by `poetry new`. It includes the project root, source code directory, tests directory, and the crucial `pyproject.toml` file.

```Text
my-project
├── pyproject.toml
├── README.rst
├── poetry_demo
│   └── __init__.py
└── tests
    ├── __init__.py
    └── test_poetry_demo.py
```

--------------------------------

### Python random.uniform() - Random Float in Range

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/modules/random-module.md

Returns a random floating point number N such that start <= N <= end for start <= end and end <= N <= start for end < start. The endpoint may or may not be included in the range.

```python
>>> random.uniform(1, 5)
# 3.697943322009309
```

--------------------------------

### Python Tuple Basics and Creation

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-data-types.md

Illustrates the creation of tuples in Python, including single-item tuples and the optional use of parentheses. It also shows how to access tuple elements by index.

```python
# Creating tuples
coordinates = (10, 20)
rgb_color = (255, 0, 128)
single_item = (42,)    # Note the comma for single-item tuples
empty = ()

# Parentheses are often optional
point = 5, 10          # Same as (5, 10)
name_age = "Alice", 25 # Same as ("Alice", 25)

# Accessing items (same as lists)
x = coordinates[0]     # 10
y = coordinates[1]     # 20
```

--------------------------------

### Create a new project with Poetry

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-projects-with-poetry-and-vscode-part-1.md

Initializes a new Python project with a standard directory structure managed by Poetry. The command `poetry new [project_name]` creates the project files and a `pyproject.toml`.

```shell
poetry new how-long
```

--------------------------------

### UV Package Manager Installation

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/virtual-environments.md

Methods to install the UV package manager, a fast drop-in replacement for pip. Installation can be done via curl for Linux/macOS or using pip.

```shell
# Using curl (Linux/macOS)
curl -LsSf https://astral.sh/uv/install.sh | sh
```

```shell
# Using pip or pipx
pip install uv
```

--------------------------------

### Poetry pyproject.toml Configuration

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/virtual-environments.md

Shows an example of the `pyproject.toml` file used by Poetry. This file defines project metadata, dependencies (both runtime and development), and build system configurations.

```TOML
[tool.poetry]
name = "my-project"
version = "0.1.0"
description = ""
authors = ["your name <your@mail.com>"]

[tool.poetry.dependencies]
python = "*"

[tool.poetry.dev-dependencies]
pytest = "^3.4"
```

--------------------------------

### Python range() with start and stop parameters

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/builtin/range.md

Shows how to use `range()` with both `start` and `stop` parameters. The loop begins at the `start` value (inclusive) and ends before the `stop` value (exclusive).

```python
>>> for i in range(1,8):
...     print(i)
# 1
# 2
# 3
# 4
# 5
# 6
# 7
```

--------------------------------

### Install Python 3.14 on Ubuntu

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-3-14-breaking-free-from-gil.md

Steps to install Python 3.14 on Ubuntu systems by adding the deadsnakes PPA, updating package lists, and installing the specific version.

```Bash
# Add the PPA
sudo add-apt-repository ppa:deadsnakes/ppa
sudo apt update

# Install Python 3.14
sudo apt install python3.14
```

--------------------------------

### UV Project and Dependency Management

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-uv-package-manager.md

Covers essential commands for initializing new projects, adding dependencies, generating lock files, and synchronizing project environments with UV.

```bash
# Create a new project
$ uv init my_project
```

```bash
# Add dependencies
$ uv add requests
```

```bash
# Create/update lockfile
$ uv lock
```

```bash
# Sync dependencies with environment
$ uv sync
```

```bash
# Run commands in project environment
$ uv run python script.py
```

--------------------------------

### pyproject.toml configuration

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-projects-with-poetry-and-vscode-part-1.md

The central configuration file for Poetry projects, replacing traditional files like `setup.py` and `requirements.txt`. It manages project metadata, dependencies, build system requirements, and more.

```toml
[tool.poetry]
name = "how-long"
version = "0.1.0"
description = "A simple decorator to measure a function execution time."
authors = ["wilfredinni <carlos.w.montecinos@gmail.com>"]

[tool.poetry.dependencies]
python = "^3.7"

[tool.poetry.dev-dependencies]
pytest = "^3.0"

[build-system]
requires = ["poetry>=0.12"]
build-backend = "poetry.masonry.api"
```

--------------------------------

### Python Built-in: sum()

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/built-in-functions.md

Sums start and the items of an iterable. The iterable must contain numbers. The start value defaults to 0.

```python
sum([1, 2, 3])
# Output: 6
sum([1, 2, 3], 10)
# Output: 16
```

--------------------------------

### Poetry Project Management Commands

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-projects-with-poetry-and-vscode-part-2.md

A collection of essential Poetry commands for managing Python projects. These commands cover project initialization, dependency management (adding, removing, updating), and environment activation.

```APIDOC
Poetry Commands:

poetry new [package-name]
  - Description: Starts a new Python project with a standard directory structure.
  - Parameters:
    - [package-name]: The name for the new Python package.

poetry init
  - Description: Interactively creates a pyproject.toml file for a new or existing project.
  - Returns: A pyproject.toml file.

poetry install
  - Description: Installs all dependencies listed in the pyproject.toml file into the virtual environment.
  - Dependencies: pyproject.toml

poetry add [package-name]
  - Description: Adds a specified package to the project's dependencies and installs it.
  - Parameters:
    - [package-name]: The name of the package to add.

poetry add -D [package-name]
  - Description: Adds a specified package as a development dependency and installs it.
  - Parameters:
    - [package-name]: The name of the development package to add.

poetry remove [package-name]
  - Description: Removes a package from the project's dependencies and uninstalls it.
  - Parameters:
    - [package-name]: The name of the package to remove.

poetry remove -D [package-name]
  - Description: Removes a development package from the project's dependencies and uninstalls it.
  - Parameters:
    - [package-name]: The name of the development package to remove.

poetry update
  - Description: Updates all project dependencies to their latest compatible versions according to pyproject.toml.
  - Dependencies: pyproject.toml

poetry shell
  - Description: Activates the project's virtual environment in the current terminal session.
```

--------------------------------

### Python reversed() Function Example

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/builtin/reversed.md

This example shows how to use the built-in reversed() function in Python. It takes a sequence (like a list) and returns an iterator that yields elements in reverse order. The example demonstrates accessing elements using the __next__() method.

```python
>>> i = reversed([1, 2, 3])
>>> i.__next__()
# 3
>>> i.__next__()
# 2
>>> i.__next__()
# 1
>>> i
# <list_reverseiterator object at 0x7f93159ded00>
```

--------------------------------

### String Slicing in Python

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/manipulating-strings.md

Explains string slicing in Python, which extracts a portion (substring) of a string. Slicing uses the syntax `[start:stop:step]`, where `start` is inclusive, `stop` is exclusive, and `step` determines the increment. Omitting `start` defaults to the beginning, `stop` to the end, and `step` to 1.

```python
>>> spam = 'Hello world!'

>>> spam[0:5]
# 'Hello'

>>> spam[:5]
# 'Hello'

>>> spam[6:]
# 'world!'

>>> spam[6:-1]
# 'world'

>>> spam[:-1]
# 'Hello world'

>>> spam[::-1]
# '!dlrow olleH'

>>> fizz = spam[0:5]
>>> fizz
# 'Hello'
```

--------------------------------

### Python List Creation and Basic Access

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-data-types.md

Shows how to create lists with various data types, access elements using positive and negative indices, and create empty lists. Lists are ordered and mutable sequences.

```python
# Creating lists
fruits = ["apple", "banana", "orange"]
numbers = [1, 2, 3, 4, 5]
mixed = ["hello", 42, True, None]  # Lists can hold different types
empty = []

# Accessing items (starts at index 0)
first_fruit = fruits[0]      # "apple"
last_fruit = fruits[-1]      # "orange"
```

--------------------------------

### Python random.randint() - Random Integer

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/modules/random-module.md

Returns a random integer N such that start <= N <= stop. Both start and stop are included in the range.

```python
random.randint(start: int, stop: int)
```

```python
>>> random.randint(1, 5)
# 3
```

--------------------------------

### Create New Project with Poetry

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/virtual-environments.md

Creates a new Python project structure managed by Poetry. This command generates a standard directory layout and a `pyproject.toml` file for project configuration and dependencies.

```Shell
poetry new my-project
```

--------------------------------

### Getting Index and Value with enumerate()

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/lists-and-tuples.md

Demonstrates using the `enumerate()` function to loop through a list while simultaneously getting both the index and the value of each item.

```python
>>> furniture = ['table', 'chair', 'rack', 'shelf']

>>> for index, item in enumerate(furniture):
...     print(f'index: {index} - item: {item}')
# index: 0 - item: table
# index: 1 - item: chair
# index: 2 - item: rack
# index: 3 - item: shelf
```

--------------------------------

### pyproject.toml [tool.poetry.dependencies] section

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-projects-with-poetry-and-vscode-part-1.md

Specifies the production dependencies required for the project, along with their version constraints. It also lists development dependencies separately in `[tool.poetry.dev-dependencies]`.

```toml
[tool.poetry.dependencies]
python = "^3.7"
...
```

--------------------------------

### Activating Poetry Shell and Opening VSCode

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-projects-with-poetry-and-vscode-part-2.md

Commands to activate the project's virtual environment using Poetry and then open the current directory in Visual Studio Code. This is a common workflow for setting up the development environment.

```shell
$ poetry shell
$ code .
```

--------------------------------

### Python max() function examples

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/builtin/max.md

Examples showing how to use the Python built-in max() function to find the largest item in a list and a tuple.

```python
>>> max([1, 2, 10, 40, 5])
# 40
>>> max((1, 2, 10, 40, 5))
# 40
```

--------------------------------

### Python Tuple Unpacking and Swapping

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-data-types.md

Explains how to unpack tuple elements into individual variables and demonstrates the common Python idiom for swapping variable values using tuple assignment.

```python
# Unpacking is very useful
point = (100, 200)
x, y = point          # x=100, y=200

# Swapping values
a = 5
b = 10
a, b = b, a           # Now a=10, b=5

# Function returning multiple values
def get_name_age():
    return "Bob", 25

name, age = get_name_age()
```

--------------------------------

### Install virtualenvwrapper-win (Windows)

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/virtual-environments.md

Installs virtualenvwrapper-win, a set of extensions to make working with virtualenv environments on Windows more convenient. It provides commands for easier environment management.

```Shell
pip install virtualenvwrapper-win
```

--------------------------------

### Add Pre-release Packages with Poetry

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/blog/python-projects-with-poetry-and-vscode-part-1.md

Installs a package that is in a pre-release state (e.g., beta, release candidate). The --allow-prereleases flag is necessary when Poetry cannot find a stable version for the specified package.

```shell
$ poetry add -D black --allow-prereleases
```

--------------------------------

### Install virtualenv (Python)

Source: https://github.com/wilfredinni/python-cheatsheet/blob/master/docs/cheatsheet/virtual-environments.md

Installs the virtualenv package, a tool for creating isolated Python environments. This is a prerequisite for using virtualenv to manage project dependencies separately.

```Shell
pip install virtualenv
```
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