To Beginners Learning with Minimum Python Environment Setup

tags: Python, Virtual Environment

Photo by Ali Shah Lakhani on Unsplash

中文版本:
https://jason19970210.medium.com/%E8%87%B4%E5%88%9D%E5%AD%B8%E8%80%85-python%E7%92%B0%E5%A2%83%E8%A8%AD%E7%BD%AE%E8%B5%B7%E6%89%8B%E5%BC%8F-79ae260520e7

Since there are lots of editors (e.g. Visual Studio Code (VSCode), Sublime, Atom, Notepad++), IDEs (Integrated Development Environment) (e.g. PyCharm, Visual Studio), web-based applications (e.g. Colab) support people to work with Python, but that always make those who don’t familiar with basic computer or programming knowledge really confusing.

What is the better setup for leaning Python ? Of course Colab is one of the simplest environment working with Python, just open a notebook. But what if working on your own PC or laptop ?

Download the Python execution from: https://www.python.org/downloads/ , then follow the instructions to complete the installation.
[Recommended]
- Windows Installer (64-bit)
- macOS default comes with Python (version 3) execution already
- Linux can be downloaded with apt or yum package manager

example:

## Linux (with sudo privilege)
$ sudo apt install python3 python3-venv

For Windows installation wizard, please check the option Add python.exe to PATH at the beginning, and Disable path length limit at the end of wizard.

Check: "Add python.exe to PATH"

Click: “Disable path length limit”

Next, check the execution works fine along with:

Beware that Windows points python to indicate Python version 3
Linux separates python as Python version 2, python3 as Python version 3

## [Windows] Command Prompt (CMD) / PowerShell (PS)
C:\Users\user> python --version
Python 3.11.3

## macOS / Linux
user@localhost $ python3 --version
Python 3.11.3

Now we are going to setup a project / working directory (aka. folder) on the Desktop, take folder name hello_world for example:

## [Windows] Command Prompt (CMD) / Powershell (PS)
C:\Users\user> cd Desktop
C:\Users\user\Desktop> mkdir hello_world

## macOS / Linux
user@localhost:~ $ cd Desktop
user@localhost:~/Desktop $ mkdir hello_world

For different purposes & dependencies for each project, we need venv (aka. Virtual Environment) to separate & isolate the packages.
P.S. $ python3 -m venv venv means calling for Python execution with the -m flag which using the module venv then make the virtual environment name as venv as the last parameter from the above command, choose your own venv name if you want.

## [Windows] Command Prompt (CMD) / PowerShell (PS)
C:\Users\user\Desktop> cd hello_world
C:\Users\user\Desktop\hello_world> python -m venv venv

## macOS / Linux
user@localhost:~/Desktop $ cd hello_world
user@localhost:~/Desktop/hello_world $ python3 -m venv venv

Then there will have a new folder called venv inside the working directory hello_world , next we are going to activate the virtual environment.

## [Windows] Command Prompt (CMD)
C:\Users\user\Desktop\hello_world> .\venv\Scripts\activate.bat

## [Windows] PowerShell (PS)
PS C:\Users\user\Desktop\hello_world> .\venv\Scripts\Activate.ps1

## macOS / Linux /* NOTICE: Check & set the exec permission */
user@localhost:~/Desktop/hello_world $ sudo chmod +x ./venv/bin/activate
user@localhost:~/Desktop/hello_world $ source ./venv/bin/activate

PowerShell must have ExecutionPolicy set before activate ps1 file.
ref: https://superuser.com/a/106362

Once we activate venv successfully, the console of the terminal will have the prefix indicated that we are inside the venv:

## [Windows] Command Prompt (CMD)
(venv) C:\Users\user\Desktop\hello_world> 

## [Windows] PowerShell (PS)
(venv) PS C:\Users\user\Desktop\hello_world>

## macOS / Linux
(venv) user@localhost:~/Desktop/hello_world $


### To deactivate ###
## [Windows] Command Prompt (CMD) / PowerShell (PS)
(venv) > deactivate
>
## macOS / Linux
(venv) $ deactivate
$

Then how to check we are using the correct Python execution ?

## [Windows] PowerShell (PS)
(venv) PS C:\Users\user\Desktop\hello_world> Get-Command python
(venv) PS C:\Users\user\Desktop\hello_world> gcm python

CommandType  Name        Version    Source
-----------  ----        -------    ------
Application  python.exe  3.11.31... C:\Users\user\Desktop\hello_world\venv\Scripts\python.exe

(venv) PS C:\Users\user\Desktop\hello_world> Get-Command pip
(venv) PS C:\Users\user\Desktop\hello_world> gcm pip

CommandType  Name     Version    Source
-----------  ----     -------    ------
Application  pip.exe  0.0.0.0    C:\Users\user\Desktop\hello_world\venv\Scripts\pip.exe

## macOS / Linux
(venv) $ which python3
/home/user/Desktop/hello_world/venv/bin/python3
(venv) $ which pip3
/home/user/Desktop/hello_world/venv/bin/pip3

Then create a main.py for testing, with Linux you can try $ touch main.py for create or short command for create + edit by vim: $ vim main.py

Install vim in Linux by :
$ sudo apt install vim -y
$ sudo yum install vim -y

# filename: main.py

print("hello world")

## [Windows] Command Prompt (CMD) / PowerShell (PS)
(venv) > python main.py

## macOS / Linux
(venv) $ python3 main.py

### Output ###
hello world

Mostly we want to add dependencies for the project, just with the command $ pip install .

If there are lots of dependencies, comes with the purpose to management about package and versions, create a requirements.txt to store more information about them, and remember to install them inside the virtual environment, example:

## filename: requirememts.txt

pandas
numpy>=1.24.3

## [Windows] Command Prompt (CMD) / PowerShell (PS)
(venv) > pip install -r requirements.txt

## macOS / Linux
(venv) $ pip3 install -r requirements.txt

We had just setup the basic for the Python working directory !
Now it’s time to add your own codes and idea to make it happened.

For the editor I recommend Visual Studio Code (link) made by Microsoft, and the IDE goes to PyCharm (link) from JetBrains.

VSCode works great for most of the cases, and has been nicely supported for basic Python script with extensions, so does ipynb format as IPython Notebook. Just select the correct interpreter then run the script, that’s all.

Keep enjoy coding with Python! Hope this article helps.