Source: California Civic Data Coalition
This map shows the number of students in each country enrolled in the online class "Python for Data Journalists" taught by Ben Welsh and the California Civic Data Coalition in 2017. More than 2,700 total students from more than 120 countries participated in the month-long course.
The code uses d3 version 4 and a threshold scale. It is based on previous choropleth maps published by Mike Bostock.