Grid-based proportional symbols layer — viz

The viz_gridprop function builds a proportional symbol map aggregated on a spatial grid. It first generates a grid from the input spatial data frame, then displays aggregated values within each cell using proportional symbols.

Usage

viz_gridprop(
  map,
  data = NULL,
  var,
  grid = "square",
  step = 15,
  level = 1,
  coords = "geo",
  missing = "white",
  symbol = "circle",
  k = 10,
  width = 30,
  straight = 0,
  fixmax = NULL,
  legend = TRUE,
  leg_type = "separate",
  leg_pos = c(10, 10),
  leg_title = NULL,
  ...
)

Arguments

map: A geoviz map created with viz_create.
data: A spatial dataframe Use data to enable iteration over features.
var: character. Name of the numeric variable used for aggregation and symbol scaling.
grid: character. Optional. Type of grid used for aggregation (default "square"). One of: "square", "dot", "diamond", "hexbin", "hex", "triangle", "arbitrary", "random", "h3", "h3geo", "hexgeo", "hexbingeo", "square_sph".
step: numeric. Optional. Grid resolution (default 15).
level: numeric. Optional. Subdivision level for hierarchical grids (default 1).
coords: character. Optional. Coordinate system (default "geo"). One of: "geo", "svg".
missing: character. Optional. Color for missing values (default "white").
symbol: character. Optional. Symbol type (default "circle"). One of: "circle", "square", "spike", "halfcircle".
k: numeric. Optional. Size of the largest symbol (default 10).
width: numeric. Optional. Width of spike symbols (default 30).
straight: numeric. Optional. Curvature of spike symbols (default 0). Value between 0 (curved) and 1 (straight).
fixmax: numeric. Optional. Maximum value for symbol scaling. Useful for map comparability.
legend: logical. Optional. Whether to display legend (default TRUE).
leg_type: character. Optional. Legend type (default "separate"). One of: "nested", "separate".
leg_pos: numeric vector. Optional. Legend position (default c(10, 10)).
leg_title: character. Optional. Legend title (default var).
...: Additional parameters passed to choropleth rendering (same as viz_choro). With the leg_ prefix, you can configure the legend. For example: leg_title, leg_subtitle, leg_note, etc.

Examples

library(sf)
world <- st_read(
  system.file("gpkg/world.gpkg", package = "geoviz"),
  quiet = TRUE
)
cities <- st_read(
  system.file("gpkg/cities.gpkg", package = "geoviz"),
  quiet = TRUE
)

viz_create(projection = "EqualEarth") |>
viz_path(datum = world, fill = "#f1f3f5") |>
viz_gridprop(data = cities, var = "population") |>
viz_render()