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 sf POINT 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)