Aggregation by Country using Map
This example visualizes the total video views from the Harvardx/MITx Course-Person Dataset, aggregated by country and displayed as graduated circles over a Mercator-projected world map. The map uses d3.geoMercator and d3.geoPath to render landmasses, graticules, and country borders from World Atlas TopoJSON, while d3.scaleSqrt maps view counts to circle radii. Points are positioned using d3.projection, and hovering reveals the country and view count via an SVG `<title>` tooltip.
AI-generated descriptionThis is a visualization of the Harvardx/MITx Course-Person Dataset for the academic year 2013. The data shows the number of video views of the online courses, represented by the circles on the map. The data can be found here.
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The world map behind the points is a Mercator type map using the World Atlas TopoJSON. The points are off by a small fraction (down and to the left) however it fits much better on the Mercator projection over the Natural Earth projection. When the user hovers over each point, they can see the latitude and logitude of that deployment.