Once a chart is ready, we can store it on the hard drive so it can be referenced in other documents. We'll see in this recipe how to save charts in different formats.
We need to install matplotlib in our virtual environment:
$ echo "matplotlib==2.2.2" >> requirements.txt
$ pip install -r requirements.txt
If you are using macOS, it's possible that you get an error like this—RuntimeError: Python is not installed as a framework. See the matplolib documentation on how to fix it: https://matplotlib.org/faq/osx_framework.html.