re: React and D3: Dynamic COVID-19 Visualizations (Part 1: World Map) VIEW POST

re: This is really great! I used leaflet and react-leaflet to build something like this.

Thank you! I would love to see your app or repo if you don’t mind sharing.


This looks great! I'll have to explore react-leaflet sometime soon. I really like that when you zoom in on your map, the scale changes so that the circles are no longer overlapping. I need to fix this with the scaling on my map. In some views, some of my smaller country circles are completely "covered" by larger circles, so they cannot be hovered over. Thank you for sharing!

I took a peek at your repo to see how the zooming worked so that circles didn't overlap when you zoom in. I could see that you had the zoom={1}. Is that just the initial zoom value for the base map? Does leaflet or react-leaflet take care of re-sizing the circles automatically for you?

Yup! The zoom refers to the initial zoom of the base map. As for the resizing effect of the Circle Markers, there isn't actually any code behind it. The radius of the circles are a function of the number of confirmed COVID cases in the region and the centers of the circles are the latitudes and longitudes of the region. Thus, if you zoom into the map, the lat and long points, i.e, the centers move away from each other while the radius remains the same. This causes the circles to not overlap when zoomed. Hope this could help!😊 Take a look at the CircleMarker element in Map.js for the radius and center.

OK, that makes sense. I decided to fix mine by just sorting the data in descending order so that the largest circles are drawn first, with smaller ones on top, so now any circle can easily be hovered over to view the data. Thank you for helping think through the options!

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