Meeting 07 - Geoprocessing - Intersect, Select, and Aggregate

Meeting Goals

This course meeting has an emphasis on the following goals:

1. Describe features that make for effective basemaps.
2. Perform spatial joins using point, line, and polygon data to identify where geometric features fall in a set of polygon features.
3. Apply these skills to create counts of points that fall within a set of polygon features.

Meeting Resources

• An overview of the meeting can be on the syllabus
• Prep videos and entry ticket are on Blackboard
• Meeting materials are available on GitHub in the module-3-intersect repository
• You can follow along with the complete code for Exercise 2 here
• Lab-07 instructions are available here

Before Class

Tasks

Please complete the tasks listed on the syllabus, and see Blackboard for the entry ticket link.

During Class

Agenda

1. Exercise 1 - Basemaps with ESRI Story Maps
2. Exercise 2 - Geoprocessing using Intersects in R
3. Short Break
4. Lab-07 and one-on-one meetings

Exercise 1 - Basemaps with ESRI Story Maps

We’ll be skipping this tonight.

Exercise 2 - Geoprocessing using Intersects in R

For our work in R today, we’ll dig into some initial geoprocessing operations using st_intersection() and st_difference(). We’ll cover working with point, line, and polygon data, and also discuss a common issue with “geometry collections.” We’ll also review skills for working with projections, and cover using dplyr’s group_by() and summarise() to aggregate counts of points for a set of polygon features.

The data and example notebook are available in this course meeting’s repository, named module-3-intersect. You can find them in examples/meeting-examples.Rmd. You can also follow along with the completed code here. Note that there are some issues with how my code is rendering right now with RStudio, and these are incomplete.

After Class

The Lab-07 instructions are available in module-3-intersect or can viewed online here.