Compute Rural Access Index (RAI)

Calculates the Rural Access Index (RAI) for a given region using datasets from the GEE Community Catalog. The RAI represents the proportion of the rural population living within 2 km of an all-season road, aligning with SDG indicator 9.1.1.

Usage

l4h_rural_access_index(
  region,
  weighted = FALSE,
  fun = NULL,
  sf = FALSE,
  quiet = FALSE,
  force = FALSE,
  ...
)

Arguments

region: A spatial object defining the region of interest. Can be an sf, sfc object, or a SpatVector (from the terra package).
weighted: Logical. If TRUE, computes a population-weighted RAI (i.e., rural population with access divided by total rural population). If FALSE, computes an area-based RAI (i.e., total pixel area with access divided by total rural area). Default is FALSE.
fun: Character. Summary function to apply to the population raster when weighted = TRUE. Common values include "mean", "sum", etc. Ignored when weighted = FALSE. Default is "mean".
sf: Logical. If TRUE, returns the result as an sf object. If FALSE, returns an Earth Engine object. Default is FALSE.
quiet: Logical. If TRUE, suppress the progress bar (default FALSE).
force: Logical. If TRUE, skips the representativity check and forces the extraction. Default is FALSE.
...: arguments of ee_extract of rgee packages.

Value

A spatial object containing the computed RAI value for the region in an sf or tibble object.

Details

This function uses the following datasets from the GEE Community Catalog:

projects/sat-io/open-datasets/RAI/ruralpopaccess/ – raster of rural population with access to all-season roads
projects/sat-io/open-datasets/RAI/inaccessibilityindex/ – binary raster indicating access areas (1 = access, 0 = no access)

When weighted = TRUE, the RAI is calculated as the sum (or chosen summary via fun) of the accessible rural population divided by the total rural population within the specified region.

When weighted = FALSE, the RAI is calculated as the ratio of pixel areas: the total area (in in km^2) with access divided by the total rural area.

The fun parameter only applies when weighted = TRUE. It will be ignored otherwise.

Credits

Pioneering geospatial health analytics and open‐science tools. Developed by the Innovalab Team, for more information send a email to imt.innovlab@oficinas-upch.pe

References

GEE Community Catalog: https://gee-community-catalog.org/projects/rai/