📦 How to manage Python libraries when you move a project to another PC

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When programming in Python, it is normal to have to install external libraries using pip.
Sooner or later, however, a fundamental question arises:

What happens when I port my Python program to another PC?

In this article, we will see:

  • what actually happens
  • why the program can stop working
  • where to run the commands (pip, venv, etc.)
  • the correct solutions based on the type of project
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🔍 The basic problem

The libraries installed with pip:

  • are not part of the code
  • are installed in the computer's Python environment

If you copy only the .py files to another PC, the program:

  • will run only if all the required libraries are already installed
  • Otherwise, it will give errors like:
ModuleNotFoundError: No module named 'library_name'

🗂 Typical Python project structure

Example:

my_project/
│
├── main.py
├── utils.py
├── requirements.txt
└── venv/ (optional)

📌 All the commands we will see must be run in the project folder, i.e. my_project/, unless otherwise specified. indication.


✅ Solution 1: requirements.txt (standard method)

This is the most common method for sharing a Python project.

📍 Where to run the commands

👉 In the project folder

cd path/my_project

🔹 Create requirements.txt

On the development PC:

pip freeze > requirements.txt

This file will contain the complete list of libraries used, for example:

requests==2.31.0
numpy==1.26.2
pandas==2.1.3

📌 The requirements.txt file should be copied with the project.

🔹 Installing the libraries on a new PC

After copying the project:

cd path/my_project
pip install -r requirements.txt

📌 It's essential to be in the same folder as requirements.txt.

✔ Pros and ❌ Cons

Pros

  • Simple
  • Standard
  • Used everywhere

Cons

  • Requires Python installed
  • Requires using the terminal

🧪 Solution 2: Virtual Environment (venv)

A virtual environment isolates a project's libraries from system libraries.

🔹 Creating the Virtual Environment

📍 In the project folder

cd my_project
python -m venv venv

Result:

my_project/
├── venv/
├── main.py
└── requirements.txt

🔹 Activating the Environment virtual

Windows

venv\Scripts\activate

Linux / macOS

source venv/bin/activate

📌 After activation, all pip install will act only within the project.

🔹 Installing libraries

pip install -r requirements.txt

✔ Pros and ❌ Cons

Pros

  • No conflicts between projects
  • Method professional

Cons

  • Requires some experience
  • Not ideal for end users

🚀 Solution 3: Create an executable (PyInstaller)

This is the ideal solution if:

  • You want to distribute the program to non-technical users
  • You don't want them to install Python or libraries

🔹 Install PyInstaller

📍 Anywhere, but recommended inside the project or in venv:

pip install pyinstaller

🔹 Create the executable

📍 In the project folder

pyinstaller --onefile main.py

Result:

dist/
└── main.exe

📌 The executable:

  • contains Python
  • contains all libraries
  • also works on PCs without Python

⚠ Important note

  • The executable must be created on each operating system
  • A Windows .exe does not work on macOS or Linux

🧠 Final summary

Scenario Solution Where to launch the commands
Share code requirements.txt Project folder
Structured Project venv + requirements.txt Project Folder
End Users PyInstaller Project Folder

✅ Conclusion

When porting a Python program to another PC:

  • Code alone is not enough
  • Libraries must be reinstalled or included

📌 The project folder is the main reference point for almost all Python programs. commands.



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