Links: PYTHON - PROGRAMMING
Rel: pip
Ref: https://www.python.org/downloads/
Tags: #public

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The most simple and effective way to install Python is to visit https://python.org/.

Under the "Downloads" tab choose the appropriate .pkg/.exe for your OS.

When the download completes, click the installer in your Downloads folder and follow the short on-screen instructions.
- Ensure to check the box to: "Add Python 3.X to PATH", which will allow you to use python or python3 from your command line.

... ->
- > macos
- > windows
- > advanced

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macos

Open Finder and navigate to /Applications/Python 3.X/.
Click the Install Certificates.command file, this will ensure that Python is able to successfully access the internet (e.g. using the requests library).

Open Terminal.app

% which python
/usr/bin/python

% which python3
/Library/Frameworks/Python.framework/Versions/3.9/bin/python3

-> python is pointing to our system's /usr/bin/python (Python 2.7), python3 is pointing to our freshly installed Python 3.9. So...

We'll use python3 to create our first virtual environment:

% python3 -m venv venv

% source venv/bin/activate
# ... {: id="..." }
(venv) % 

Using source ^^, we are able to active it.

We can have it activated by default anytime when opening a new Terminal.app window open adding to our sh profile (found at ~/.bashrc or ~/.zshrc) by adding the following lines:

# ... {: id="..." }
alias activate=". ~/venv/bin/activate"
activate
# ... {: id="..." }

Otherwise, notice that anytime you open Terminal.app, your prompt (e.g. %) isn't prepended with e.g. (venv).

See pip for more about virtual environments.

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windows

Open cmd.exe.

C:\> where python3
C:\Users\alice\AppData\Local\Microsoft\WindowsApps\python3.exe

C:\> where python
C:\Users\alice\AppData\Local\Programs\Python\Python3X\python.exe
C:\Users\alice\AppData\Local\Microsoft\WindowsApps\python3.exe

-> python3 is pointing to open a link to the Windows Store, python (firstly) points to our freshly installed Python 3.9. So...

We'll use python to create our first virtual environment:

C:\> python -m venv venv

C:\> .\venv\Scripts\activate
# ... {: id="..." }
(venv) C:\> 

Using .\venv\bin\activate we are able to activate it and the prepended (venv) let's us know it has been activated.

Additionally:
pip install wheel pyreadline to enable Tab-auto-completions within the python shell.

See pip for more about virtual environments.

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advanced

...via package managers:
- macos: see homebrew to learn how to brew install python@3.x directly from Terminal.app.
- windows: see chocolatey to learn how to choco install python directly from cmd.exe.
- linux: e.g. sudo apt-get install python 3.x (if not already found installed python3 -v), and additionally sudo apt-get -y python3-pip python3-dev python3-venv if necessary.