Proportional symbols layer — viz

The viz_prop function creates a proportional symbol layer from a spatial data frame. It can display different symbol types (circle, square, spike, half-circle) sized according to a numeric variable, and optionally includes a legend.

Usage

viz_prop(
  map,
  data = NULL,
  var,
  symbol = "circle",
  k = 50,
  fixmax = NULL,
  width = 30,
  straight = 0,
  dodge = FALSE,
  legend = TRUE,
  leg_type = "nested",
  leg_pos = c(10, 10),
  ...
)

Arguments

map: A geoviz map created with viz_create.
data: A spatial dataframe
var: character. Variable name containing numeric values used for scaling symbols.
symbol: character. Optional. Symbol type (default "circle"). One of: "circle", "square", "spike", "halfcircle".
k: numeric. Optional. Size of the largest symbol (default 50).
fixmax: numeric. Optional. Value corresponding to the symbol of size k. Useful to ensure comparability between maps.
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).
dodge: logical. Optional. Avoid symbol overlap (default FALSE, circle only).
legend: logical. Optional. Whether to display a legend (default TRUE).
leg_type: character. Optional. Legend type (default "nested"). One of: "nested", "separate".
leg_pos: numeric vector. Optional. Legend position (default c(10, 10)).
...: Additional parameters passed to symbol rendering (e.g. strokeWidth). 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
)

viz_create(
  projection = "EqualEarth", background = "white",
  zoomable = TRUE
) |>
viz_path(
  datum = world, fill = "#f1f3f5"
) |>
viz_prop(
  data = world, var = "pop", symbol = "circle", fill = "#38896F",
  k = 25, leg_values_round = 0, leg_title = "Population",
  leg_subtitle = "(million inh.)", leg_values_factor = 1 / 1000000
) |>
viz_render()