Description
Voter Distance to Polling Locations.
Description
Calculates the distance between each voter in a voter file (given lat/long coordinates or sf point geometries) and multiple polling or vote-by-mail drop box locations. Returns nearest location, k-nearest locations, or all locations within a distance threshold. Core computation uses the Haversine formula implemented in C++ via 'Rcpp'.
README.md
Rvoterdistance
Calculates the geographic distance between voters in a voter file and multiple polling or vote-by-mail drop box locations using the Haversine (great-circle) formula. Core computation is implemented in C++ via Rcpp for speed.
Features
- Nearest location: find the single closest polling place for each voter
- k-nearest locations: find the k closest locations per voter
- Distance threshold: find all locations within a specified radius (e.g., all drop boxes within 5 miles)
- sf integration: pass
sfPOINT geometries directly with automatic CRS transformation to WGS-84 - Progress reporting: optional progress output for large voter files
- Units: results in meters, kilometers, and miles
Installation
# From GitHub:
remotes::install_github("lorenc5/Rvoterdistance")
Quick Start
library(Rvoterdistance)
data(meck_ev)
# Nearest early voting location for each voter
result <- nearest_location(voter_meck, early_meck,
voter_coords = c("lat", "long"),
location_coords = c("lat", "long"))
head(result)
# 3 nearest locations per voter
result_k3 <- nearest_location(voter_meck, early_meck,
voter_coords = c("lat", "long"),
location_coords = c("lat", "long"),
k = 3)
# All locations within 5 miles
result_5mi <- nearest_location(voter_meck, early_meck,
voter_coords = c("lat", "long"),
location_coords = c("lat", "long"),
max_dist = 5, units = "miles")
Main Functions
| Function | Description |
|---|---|
nearest_location() | Main entry point. Supports k-nearest, distance threshold, sf objects. |
dist_km() | Minimum distance to nearest location in kilometers. |
dist_mile() | Minimum distance to nearest location in miles. |
haversine() | Single-pair great-circle distance with configurable units. |
Using sf Objects
library(sf)
voters_sf <- st_as_sf(voter_meck, coords = c("long", "lat"), crs = 4326)
locs_sf <- st_as_sf(early_meck, coords = c("long", "lat"), crs = 4326)
result <- nearest_location(voters_sf, locs_sf)
If the CRS is not WGS-84 (EPSG:4326), coordinates are automatically transformed.
Included Data
- king_dbox / king_geo: King County, WA ballot drop box locations and voter sample
- meck_ev (voter_meck / early_meck): Mecklenburg County, NC early voting locations and voter sample
Citation
Collingwood, Loren. 2026. Rvoterdistance: Voter Distance to Polling Locations. R package version 2.0.0. https://github.com/lorenc5/Rvoterdistance
License
GPL (>= 2)