In this Matplotlib tutorial, we're going to be going over custom legends. We've covered the basics of adding a legend already.
The main issue with legends is typically that the legend gets in the way of data. There are a few options here. One option is to put the legend outside of the axis, but we have multiple subplots here and that would be pretty difficult. Instead, we'll make the legend a bit smaller, and then apply an alpha to it.
First, to have a legend, we need to add labels to our data that we want to show up on the legend.