ABSTRACT
To display data on a variety of COVID-19 metrics, interactive geospatial visualization is used by websites ranging from the New York Times and the Washington Post to GitHub and Flickr. This chapter explores the interactive geospatial visualization of the data. It introduces the “leaflet” R package and illustrates basic usages and properties with several examples of disease mapping at state and county levels. Unlike static visualization R packages like “ggplot2” or “ggmap,” the maps constructed by the R package “leaflet” are fully interactive and can include features like interactive panning, zooming, popups, tooltips and labels, as well as highlighting and selecting regions. The chapter demonstrates how to draw a county-level choropleth map to illustrate the spatial variation from county to county by making use of the datasets counties1 and counties2 from the IDDA package. It closes with an illustration of integrating “leaflet” with R Shiny.
