DEV Community: Clément Dethoor

Python data types reminder

Clément Dethoor — Sat, 24 May 2025 19:24:21 +0000

🐍 Python Built-in Data Types

Python has several built-in data types grouped into categories:

📦 Basic Types

Type	Description	Example
`int`	Integer numbers	`x = 10`
`float`	Floating-point numbers	`pi = 3.14`
`complex`	Complex numbers	`z = 2 + 3j`
`bool`	Boolean values (`True` or `False`)	`is_valid = True`
`str`	Text (string)	`name = "Alice"`
`NoneType`	Represents the absence of a value	`x = None`

📚 Sequence Types

Type	Description	Example
`list`	Ordered, mutable sequence	`fruits = ["apple", "banana"]`
`tuple`	Ordered, immutable sequence	`point = (1, 2)`
`range`	Sequence of numbers (typically for loops)	`range(5)` → `0,1,2,3,4`

🔑 Mapping Type

Type	Description	Example
`dict`	Key-value pairs	`user = {"name": "Alice", "age": 30}`

🔢 Set Types

Type	Description	Example
`set`	Unordered, unique items	`colors = {"red", "blue"}`
`frozenset`	Immutable set	`fs = frozenset([1, 2, 3])`

🧵 Binary Types

Type	Description	Example
`bytes`	Immutable sequence of bytes	`b = b"hello"`
`bytearray`	Mutable sequence of bytes	`ba = bytearray(b"hello")`
`memoryview`	Memory view of a byte object	`mv = memoryview(b"hello")`

🛠️ Type Checking

type(42)          # <class 'int'>
isinstance("hi", str)  # True

🧠 Tip

Use type() to inspect a value’s type, and isinstance() to check if a value matches a certain type.

Introduction to UV

Clément Dethoor — Sat, 24 May 2025 19:20:19 +0000

UV – Ultra Fast Python Package Manager

🧾 Overview

UV is an extremely fast Python project and package manager written in Rust.

Manages dependencies, virtual environments, and Python versions.
Can replace pip, pipx, pip-tools, or poetry.
Blazing fast due to being built in Rust.

⚙️ Installation

On macOS (via Homebrew)

brew install uv

Using pip

pip install uv

Enable shell auto-completion (e.g., for zsh)

eval "$(uv generate-shell-completion zsh)"

Example: uv c[TAB] will autocomplete the command.

🚀 Setting Up a Project

Initialize a project

uv init --app my_app_name        # Default type (application)
uv init --package my_package_name
uv init --lib my_lib_name

Run a script and create a virtual environment

uv run hello.py

This will create a virtual environment automatically.

Add or remove dependencies

uv add pandas
uv remove pandas

Sync environment and workspace

uv sync

Upgrade a specific package

uv lock --upgrade pandas

Show dependency tree

uv tree

📦 Dependency Management (Workspaces)

UV supports workspaces, allowing you to manage multiple virtual environments in a single directory.

Running uv init inside an existing UV project creates a sub-project with its own virtual environment:

uv init new_project
uv add pandas

To create a fully isolated project (not in the workspace):

uv init another_project --no-workspace

🛠️ UV Tools

Run a tool (e.g., `ruff`)

uv tool run ruff check

Check where tools are installed

uv tool dir

Install a tool

uv tool install ruff

🐍 Python Version Management

List available Python versions

uv python list

Install a specific version

uv python install 3.12.0

Set Python version for a virtual environment

uv venv --python 3.12.0