a5view

Interactive map viewer for A5 geospatial cells, powered by deck.gl. Renders cells directly in the browser using deck.gl’s native A5Layer — no pre-computation of boundaries needed. Intentionally minimal API for fast prototyping and exploration of A5 data.

Installation

# install.packages("pak")
pak::pak("belian-earth/a5view")

Usage

library(a5R)
library(a5view)

# Pick a cell and expand to a disk
cell <- a5_lonlat_to_cell(-3.19, 55.95, resolution = 9)
disk <- a5_grid_disk(cell, k = 10) |>
  a5_uncompact(resolution = 9)

# Colour by distance from centre
a5_view(disk, fill = a5_cell_distance(cell, disk), palette = "Inferno")

Features:

• Colour mapping from numeric vectors or data frame columns with any hcl.colors() palette
• Interactive basemap selector (dark, light, OSM, satellite)
• Opacity slider
• Tooltip with cell ID on click, fill value on hover
• Cell border styling
• 3D extrusion via elevation
• Shiny bindings (a5_viewOutput / renderA5_view)
• Optional polygon-draw toolbar (draw_polygon = TRUE) for selecting an area of interest

Polygon draw mode (Shiny only)

Setting draw_polygon = TRUE adds a draw-polygon toggle to the toolbar. Clicks place vertices, a double-click closes the polygon, and the result is sent to Shiny as a WKT string at input$<id>_polygon_draw. The widget itself does not visualise which cells fall inside the polygon — the canonical pattern is to resolve the WKT server-side and update the map fills via a5_view_update(). Outside Shiny there is no input listener, so the feature has no effect.

a5_viewOutput("map")

# server
output$map <- renderA5_view({
  a5_view(my_cells, draw_polygon = TRUE)
})

observeEvent(input$map_polygon_draw, {
  cells_in_poly <- a5R::a5_grid(wk::wkt(input$map_polygon_draw), resolution = 4L)
  # ... use cells_in_poly, e.g. a5_view_update() with selection-driven fills.
})

See inst/examples/polygon-select/app.R for a complete demo combining single-cell click selection with polygon-based selection.