What is the best project structure for a Python application?

There is no one "best" project structure for a Python application, as it often depends on the specific requirements and goals of the project. However, a common and recommended structure for a Python application is to use a package-based directory layout, with a separate directory for the main module and subdirectories for different components of the application, such as the modules, tests, and data.

Here is an example of a basic package-based directory layout for a Python application:

myproject/
    myproject/
        __init__.py
        main.py
        module1/
            __init__.py
            module1.py
        module2/
            __init__.py
            module2.py
    tests/
        __init__.py
        test_module1.py
        test_module2.py
    data/
        data1.json
        data2.csv

In this example, the myproject directory contains the main module and subdirectories for different components of the application, such as module1 and module2. The tests directory contains test modules for the different components of the application. The data directory contains data files that are used by the application.

It's also a good practice to use a .env file or config.py to store all the sensitive information like the credentials, database url and other environment variables.

It's important to note that this is just one example and it could change depending on the size and complexity of the project.