Learn Python by Building Data Science Applications

Drawing maps with Altair

Now, let's reproduce the map. It is actually pretty straightforward. First, we need to specify the source for the boundaries dataset and the properties of the projection:

url = 'https://unpkg.com/world-atlas@1/world/50m.json'data_geo = alt.topo_feature(url, feature='countries')proj = {'center':[10, 52], 'type':'conicEquidistant', 'scale':800}

As you can see, Altair can be linked to the data source and will pull the data from the web during runtime. It is a nice feature, as we can similarly link it to the dataset we'll be constantly updating, hence getting a real-time data snapshot. We'll use that option in Chapter 17, Let's Build a Dashboard, to build a dashboard. Now, we will create another chart object, using projection ...