Until now, we have used the matplotlib library, via the built-in pandas interface. matplotlib is powerful and essential to Python's data visualization ecosystem. It is not, however, the only visualization library we can use. In fact, there are a plethora of visualization tools, different in their format, focus, or even philosophy. In this section, we'll introduce you to a different tool—and different concept of data visualization—and that is altair, which is a Python library based around the Vega engine. What makes it so different? A couple of things, in fact.
First of all, its core philosophy is based on the declarative approach, which can be boiled down to the following principle: the core idea is to write each chart in code as a declaration—basically, a recipe. This declaration would define what to...