It is recommended that you use virtualenv to create isolated Python environments, so that you can use different package versions for different projects, which is far more practical than installing Python packages system-wide. Another advantage of using virtualenv is that you won't need any administration privileges to install Python packages. Run the following command in your shell to install virtualenv:
pip install virtualenv
After you install virtualenv, create an isolated environment with the following command:
virtualenv my_env
This will create a my_env/ directory, including your Python environment. Any Python libraries you install while your virtual environment is active will go into the my_env/lib/python3.6/site-packages ...
