When trying to visualize and plot data in Python you might work with Matplotlib. In case you are working on MacOS and you use a venv, in some cases you might run into the below error message:
RuntimeError: Python is not installed as a framework. The Mac OS X backend will not be able to function correctly if Python is not installed as a framework. See the Python documentation for more information on installing Python as a framework on Mac OS X. Please either reinstall Python as a framework, or try one of the other backends. If you are using (Ana)Conda please install python.app and replace the use of 'python' with 'pythonw'. See 'Working with Matplotlib on OSX' in the Matplotlib FAQ for more information.
This should remove (in most cases) the error and your code should be able to run correctly.