Analyzing data

The first half of this chapter creates the analysis functionality, while the other half weaves the functionality into the application design. Let's begin by making the functionality. This includes overlap summary and buffer for vector data and zonal statistics for raster data.

Vector data

For vector data, we will focus on two commonly used analysis tools: overlap summary and buffer.

Overlap summary

One of the most basic spatial analysis operations in a GIS is to summarize statistics for a layer of features that touches or overlaps another layer of features. Typical questions to warrant such analysis include: how many points fall within each country polygon, or what is the sum or average of their values for each country? This type of analysis is typically done using a spatial join tool, with the many-to-one option representing multiple matching features with a summary statistic. These summary statistics are then attached to the original country polygons. A spatial join is not an...