analyze_green_accessibility: Analyze Green Space Accessibility Using Street Network

In greenR: Green Index Quantification, Analysis and Visualization

Analyze Green Space Accessibility Using Street Network

Description

Computes green space accessibility using network distances from grid centroids to the nearest green area. Supports travel modes like walking, cycling, and driving by filtering appropriate road types and assigning travel speed. Optionally supports population-weighted metrics if population raster data is provided (e.g., GHSL).

Usage

analyze_green_accessibility(
  network_data,
  green_areas,
  mode = "all",
  grid_size = 500,
  population_raster = NULL
)

Arguments

network_data	sf object or osmdata object with osm_lines representing street network.
green_areas	sf object or osmdata object with osm_polygons representing green areas.
mode	Character. One of "walking", "cycling", "driving", or "all". Defaults to "all".
grid_size	Numeric. Grid cell size in meters. Default is 500.
population_raster	Optional. A terra::SpatRaster object with gridded population data (e.g., GHSL).

Value

A named list by mode. Each element contains:

grid

An sf grid with per-cell accessibility and population metrics.

stats

Data frame with spatial and population-weighted accessibility metrics.

summary

Named list of summary statistics for plotting or reporting.

Examples

## Not run: 
# Example 1: Green accessibility using OSM network and green polygons, no population
data <- get_osm_data("City of London, United Kingdom")
result_no_pop <- analyze_green_accessibility(
  network_data = data$highways$osm_lines,
  green_areas = data$green_areas$osm_polygons,
  mode = "walking",
  grid_size = 300
)
print(result_no_pop$stats)

# Example 2: With GHSL population raster (if you have the raster file)
library(terra)
ghsl_path <- "GHS_POP_E2025_GLOBE_R2023A_54009_100_V1_0_R4_C19.tif"  # Update path as needed
pop_raster_raw <- terra::rast(ghsl_path)

# Optionally, crop raster to the city area (recommended for speed)
# aoi <- sf::st_transform(st_as_sfc(st_bbox(data$highways$osm_lines)), terra::crs(pop_raster_raw))
# pop_raster_raw <- terra::crop(pop_raster_raw, aoi)

result_with_pop <- analyze_green_accessibility(
  network_data = data$highways$osm_lines,
  green_areas = data$green_areas$osm_polygons,
  mode = "walking",
  grid_size = 300,
  population_raster = pop_raster_raw
)
print(result_with_pop$stats)

## End(Not run)

greenR documentation built on Nov. 30, 2025, 5:06 p.m.