Move plt import inside functions that use it

[Erotemic]

I'm interested in using this package in a production system.

Overall, it is very well structured and easy to use. There is one tiny issue: matplotlib.pyplot has import-time side effects. There is a lot to say here, but the upshot is that you need to ensure you have all matplotlib backend 100% configured before you import pyplot, otherwise it can lead to unexpected results.

The matplotlib library itself doesn't have this issue, so it's safe to import that at the top-level, but pyplot is another story. A reasonable workaround is to simply delay the import of pyplot until you actually need it. That gives any external system a change to import all of it's main libraries and then do any user-specific backend customization before any plots are generated.

This is all to say: I moved the import matplotlib.pyplot as plt imports into the functions that used them.

Let me know what you think / if there are any issues that you foresee in making this change.

[jack89roberts]

Happy with this one too 👍