ZCTA Contiguity Validation

This R project introduces a helper function designed to evaluate the contiguity of ZIP Code Tabulation Areas (ZCTAs). Utilizing sf::st_union(), the function discerns whether input geometries coalesce into a singular POLYGON (indicating contiguity) or a MULTIPOLYGON (indicating discontiguity), thereby determining the spatial continuity of ZCTAs.

Getting Started

These instructions will get you a copy of the project up and running on your local machine for development and testing purposes.

Prerequisites

The project uses renv for dependency management. Make sure you have renv installed in your R environment:

if (!require(renv)) install.packages("renv")

Installation

1. Clone this repository or download the project to your local machine.
2. Open R or RStudio and set the working directory to the project's root directory.
3. Run renv::restore() to install the necessary packages as specified in the renv.lock file:

renv::restore()

This command will install all the project's dependencies, ensuring that you have the correct versions of each package.

Usage

The core functionality resides in the zcta-contiguity.R script located under the R/ subdirectory. Follow these steps to execute the script:

1. Ensure you are in the project's root directory.
2. Source the zcta-contiguity.R script:

source("R/zcta-contiguity.R")

The script performs the following actions:

• Load Dependencies: Uses box::use to import specific functions from required packages.
• Define Helpers: Contains the is_contiguous_polygon function for checking if the input spatial feature (ZCTAs) forms a contiguous polygon.
• Data Preparation: Retrieves and prepares urban area and ZCTA data for Portland, Oregon, as an example.
• Contiguity Analysis: Demonstrates checking for contiguity among ZCTAs in Oregon and specifically within the Portland urban area.

License

This project is licensed under the MIT License - see the LICENSE.md file for details.