Geographic Tools for Studying Gerrymandering.

geomander

Focuses on creating data sets and other tools that help make understanding gerrymandering faster and easier. Designed for easy preparation to run simulation analysis with the R package redist, but is aimed at the geographic aspects of redistricting, not partitioning methods. Most of these tools are gathered from seminar papers and do not correspond to a single publication.

Installation

You can install the released version of geomander from CRAN with:

install.packages("geomander")

And the development version from GitHub with:

# install.packages("devtools")
devtools::install_github("christopherkenny/geomander")

Examples

A very common task is aggregating block data to precincts.

library(geomander)
library(tidyverse)
#> ── Attaching core tidyverse packages ──────────────────────── tidyverse 2.0.0 ──
#> ✔ dplyr     1.1.4     ✔ readr     2.1.4
#> ✔ forcats   1.0.0     ✔ stringr   1.5.1
#> ✔ ggplot2   3.4.4     ✔ tibble    3.2.1
#> ✔ lubridate 1.9.3     ✔ tidyr     1.3.0
#> ✔ purrr     1.0.2     
#> ── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
#> ✖ dplyr::filter() masks stats::filter()
#> ✖ dplyr::lag()    masks stats::lag()
#> ℹ Use the conflicted package (<http://conflicted.r-lib.org/>) to force all conflicts to become errors
 
# load precincts
data('va18sub')

# create block data
block <- create_block_table(state = 'VA', county = '087')  

# match the geographies
matches <- geo_match(from = block, to = va18sub)

# Aggregate
prec <- block2prec(block_table = block, matches = matches)

Other important tasks include breaking data into pieces by blocks underlying them.

library(geomander)
library(tidyverse)
 
# load precincts
data("va18sub")

# subset to target area
va18sub <- va18sub %>% filter(COUNTYFP == '087')

Then we can get common block data:

block <- create_block_table(state = 'VA', county = '087')  

And estimate down to blocks

disagg <- geo_estimate_down(from = va18sub, to = block, wts = block$vap, value = va18sub$G18USSRSTE)

For more information, see the documentation and vignettes, available at https://christophertkenny.com/geomander/