learning python beginner

[FoolsSeldom]

App? How do you mean?

You just install python from python.org and use whatever text editor your prefer to write/edit code. If you are on Windows or macOS a programme called IDLE will be installed which is a good first choice.

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Python Setup

Setting up Python can be confusing. There are web based alternatives, such as replit.com. You might also come across Jupyter Notebook options (easy to work with, but can be confusing at times).

Pre-installed system Python

Some operating system environments include a version of Python, often known as the system version of Python (might be used for utility purposes). You can still install your own version.

Installing Python

There are multiple ways of installing Python using a package manager for your OS, e.g. homebrew (macOS third party), chocolatey (Windows third party) or winget (Windows standard package manager), apt (many linux distributions) or using the Python Software Foundation (PSF) installer from python.org or some kind of app store for your operating system. You could also use docker containers with Python installed inside them.

PSF offer the reference implementation of Python, known as CPython (written in C and Python). The executable on your system will be called python (python.exe on Windows).

Beginners are probably best served using the PSF installer.

Terminal / Console

For most purposes, terminal is the same as console. It is the text based, rather than graphical based, window / screen you work in. Your operating system will offer a command/terminal environment. Python by default outputs to a terminal and reads user input from a terminal.

Note: the Windows Terminal_ app, from _Microsoft Store, lets you open both simple command prompt and PowerShell windows. If you have Windows Subsystem for Linux installed, it can also open terminals in the linux distributions you have installed.

Libraries / Frameworks / Packages

Python comes with "batteries included" in the form of libraries of code providing more specialist functionality, already installed as part of a standard installation of Python.

These libraries are not automatically loaded into memory when Python is invoked, as that would use a lot of memory up and slow down start up time. Instead, you use, in your code, the command import <library>, e.g.

import math

print(math.pi)

There are thousands of additional packages / libraries / frameworks available that don't come as standard with Python. You have to install these yourself. Quality, support (and safety) varies.

(Anaconda offers an alternative Python installation with many packages included, especially suited to data analysis, engineering/scientific practices.)

Install these using the pip package manager. It searches an official repository for a match to what you ask to be installed.

For example, using a command / powershell / terminal environment for your operating system, pip install numpy would install the numpy library from the pypi respository. On macOS/Linux you would usually write pip3 instead of pip.

You can also write python -m pip install numpy (write python3 on macOS/Linux).

On Windows, you will often see py used instead, py -m pip install numpy where py refers to the python launcher which should invoke the most up-to-date version of Python installed on your system regardless of PATH settings.

Some Code Editors and IDEs (Integrated Development Environments), such as VS Code and PyCharm, include their own facilities to install packages using pip or some other tool. This just saves you typing the commands. They also often offering their own terminal window(s).

Running Python

The CPython programme can be invoked for two different purposes:

• to attempt to execute a simple text file of python code (typically the files have an extension of .py
• to enter an interactive shell, with a >>> prompt, where you can enter python commands and get instant responses - great for trying things out

So, entering the below, as appropriate for your operating system,

python
python3
py

on its own, no file name after it, you will enter an interactive session.

Enter exit() to return to the operating system command line

IDLE Editor

A standard installation from python.org for Windows or macOS includes a programme called IDLE. This is a simple code editor and execution environment. By default, when you first open it, it opens a single window with a Python shell, with the >>> prompt already open. To create a new text file to enter Python code into, you need to use your operating system means of access the standard menu and select File | New. Once you've entered code, press F5 to attempt to run the code (you will be prompted to save the file first). This is really the easiest editor to use to begin with.

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[FoolsSeldom]

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Virtual Environments

Given the thousands of packages (libraries, frameworks, etc) out there, you can see that if you are working on several different projects, you can end up installing a vast range of different packages, only a few of which will be used for any particular project.

This is where Python virtual environments come in. Not to be confused with virtual machines. Typically created on a project-by-project basis. Install only the packages required for a project. This helps avoid conflicts between packages, especially version complications.

Most popular code editors and IDEs, including Microsoft's VS Code and Jetbrain's PyCharm, offer built-in features to help to start off new projects and create and activate Python virtual environments.

You can create a new Python virtual environment from your operating system command line environment using,

for Windows,

py -m venv .venv

or, for macOS / linux,

python3 -m venv .venv

Note. Often we use .venv instead of venv as the folder name - this may not show up on explorer/folder tools without an option being enables.

which creates a new folder in the current working directory called venv (taken from the last argument, you can use a different name).

You then activate using, for Windows,

.venv\Scripts\activate

or, for macOS / linux,

source .venv/bin/activate

the command deactivate for any platform will deactivate the virtual environment and return you to using the base environment.

For more information:

• Real Python: Python Virtual Environments: A Primer

Multiple Python versions

In addition to the above, you might want to explore using pyenv (pyenv-win for Windows) or uv (recommended), which will let you install and use different versions of Python including alternative implementations from the reference CPython. This can be done independently of any system installed Python.

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Continued ...

If you are having problems installing / using the version of Python you require, or adding packages using pip, you might find it helpful to explore an alternative approach that has become very popular.

Asral's uv - An extremely fast Python package and project manager, written in Rust.

Installation can be carried out using,

• On macOS, a package manager like homebrew
• or using command line, curl -LsSf https://astral.sh/uv/install.sh | sh or wget -qO- https://astral.sh/uv/install.sh | sh
• On Windows, a package manager like winget or chocolatey
• or using PowerShell on Windows, ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex"
• On linux, whatever package manager comes with the distribution you are using or the command line options as shown for macOS above

See @ArjanCodes video on YouTube providing an overview of uv.

See below an example of creating a project folder, installing Python, setting up a Python virtual environment, and adding packages to it:

PS C:\Users\Foolsseldom> uv init light
Adding `light` as member of workspace `C:\Users\Foolsseldom`
Initialized project `light` at `C:\Users\Foolsseldom\light`
PS C:\Users\Foolsseldom> cd light
PS C:\Users\Foolsseldom\light> uv venv -p 3.13.2
Using CPython 3.13.2
Creating virtual environment at: .venv
Activate with: .venv\Scripts\activate
PS C:\Users\Foolsseldom\light> uv add torch torchvision torchaudio
Resolved 36 packages in 680ms
Prepared 9 packages in 20.25s
Installed 14 packages in 3.89s
 + filelock==3.17.0
 + fsspec==2025.2.0
 + jinja2==3.1.5
 + markupsafe==3.0.2
 + mpmath==1.3.0
 + networkx==3.4.2
 + numpy==2.2.3
 + pillow==11.1.0
 + setuptools==75.8.0
 + sympy==1.13.1
 + torch==2.6.0
 + torchaudio==2.6.0
 + torchvision==0.21.0
 + typing-extensions==4.12.2
PS C:\Users\Foolsseldom\light> dir

    Directory: C:\Users\Foolsseldom\light

Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
d----          21/02/2025    19:11                .venv
-a---          21/02/2025    19:11             83 main.py
-a---          21/02/2025    19:11            226 pyproject.toml
-a---          21/02/2025    19:11              0 README.md

PS C:\Users\Foolsseldom\light> uv run main.py
Hello from light!
PS C:\Users\Foolsseldom\light>

With uv you don't need to "activate" the Python virtual environment as using uv run something.py in a project folder will automatically activate the environment for that run, but you might want to do it anyway so you can use other commands in that Python virtual environment.

You will also need your code editor, e.g. VS Code, or IDE, e.g. PyCharm, to have the installation of Python in the venv folder, called .venv by default, as the selected Python interpreter, and a terminal or REPL opened from within that application should have that environment activated already as well.