VORONOI TESSELLATION DEFINITION DOWNLOAD
For geographic context, we download the 2019 USA counties cartographic boundary file from the Census website and subset to get the border of Alameda County. We use the California Healthcare Facility Listing data that we downloaded from the CA Health & Human Services Open Data Portal. In this example we look at service areas around hospitals in Alameda County, CA. Keep in mind that this is only an informational example and not a real analysis workflow which would be more complex. Let's take a look at some of the many ways in which proximity analysis can be implemented in R. The resultant polygons, called Thiessen polygons, are shown in the image below. A Voronoi diagram partitions the area around a set of features into regions where each location within the region is closer to the contained feature than to any other feature. Another tool for exploring proximity is Voronoi diagram, which is also called Voronoi tessellation, a Voronoi decomposition, a Voronoi partition, or a Dirichlet tessellation. This necessitates the definition of the buffer distance and a clear explanation of why that distance was selected. A buffer polygon delineates an area or area within a defined radius of a feature of interest. It is at the heart of the Tobler's first law of geography which I paraphrase as "Everything is related but near things are more related." In practice, proximity analysis is often implemented with buffer polygons. It refers to the ways in which we use spatial methods to ask "what is happening near here". Proximity analysis is one of the cornerstones of spatial analysis.
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