From Chen Ding: Aggregation by Country using Excel + Dropdowns!
This example visualizes the number of video views for HarvardX/MITx online courses in the 2013 academic year. Circles, sized by total views, are positioned on a world map according to viewer location, with a dropdown menu to filter by specific course. A tooltip reveals the country and view count for each circle. The visualization uses a Mercator projection via `geoMercator`, renders map features with `geoPath`, and calculates the circle sizing using `scaleSqrt` from D3 v5. The map data comes from the World Atlas TopoJSON, while view data is loaded from a CSV file.
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.