Question
Answer and Explanation
The discrepancy between a package appearing in pip list and a ModuleNotFoundError in a Conda environment typically arises from the way Conda and Pip manage packages and environments.
Here's a breakdown of why this can happen:
1. Isolated Environments: Conda environments are designed to be isolated. When you create a Conda environment (e.g., using conda create -n myenv python=3.9), you're establishing a self-contained space for your project's dependencies. This isolation helps prevent conflicts between different projects that require different package versions.
2. Separate Package Managers: Conda and Pip are different package managers. Conda is primarily for managing binary packages and dependencies across different platforms, while Pip is primarily for managing Python packages (often from PyPI). Each maintains its own list of installed packages within an environment.
3. Pip's Global Perspective: When you use pip list, it shows you the packages installed in the environment where Pip is being run. If you're running Pip outside of your activated Conda environment or if you've installed packages using Pip outside the Conda environment, pip list might show loguru even if it isn't installed within the active Conda environment.
4. Conda's Local Perspective: When you run a Python script within an activated Conda environment, Python will only look for packages within that specific environment's site-packages directory. If loguru was installed outside this environment using Pip, Python will not find it and raise a ModuleNotFoundError.
5. Order of Installation: If you installed loguru using Pip after creating the Conda environment but without activating it, it would be installed outside the Conda env's site-packages.
How to Solve the Issue:
- Activate the Conda Environment: Always activate your Conda environment before installing or running anything. Use conda activate myenv (or whatever your environment is named).
- Install Within the Environment: Use conda install loguru or pip install loguru while the environment is activated. It’s recommended to prefer conda install whenever possible, because conda manages also system level dependencies, however, if you want to use pip, remember to install all other packages with pip.
- Verify with Conda List: Use conda list to check the packages installed inside the activated Conda environment. This command will accurately reflect the packages available in that environment.
- Avoid Mixing Pip and Conda: While Pip can be used within Conda environments, it's generally best practice to use Conda for package management within Conda environments to ensure proper dependency handling. If you choose to use pip, be consistent and use pip install for all packages inside your environment.
In summary, if loguru is listed by pip list but not found within your Conda environment, it's highly likely that loguru was installed using Pip outside your active Conda environment. Install it within the activated environment using conda install loguru or pip install loguru and always verify installed packages using conda list when working within a Conda environment.