Proportional + choropleth combined layer — viz

The viz_propchoro function combines proportional symbols and choropleth mapping on the same spatial data frame. It allows simultaneous encoding of two numeric variables using symbols (size) and colors (classification).

Usage

viz_propchoro(
  map,
  data = NULL,
  var1,
  var2,
  var = NULL,
  symbol = "circle",
  k = 50,
  fixmax = NULL,
  dodge = FALSE,
  width = 30,
  straight = 0,
  method = "quantile",
  nb = 6,
  breaks = NULL,
  colors = NULL,
  middle = FALSE,
  sd = 1,
  reverse = FALSE,
  missing = "white",
  legend = TRUE,
  leg1_type = "nested",
  leg2_type = "vertical",
  leg1_pos = c(10, 10),
  leg2_pos = NULL,
  ...
)

Arguments

map: A geoviz map created with viz_create.
data: A spatial dataframe Use data to enable iteration over features.
var1: character. Name of the numeric variable used for absolute values (driving symbol size).
var2: character. Name of the numeric variable used for relative values (driving color classification, e.g. percentages).
var: character. Optional. If provided, the same variable is used for both size and color encoding.
symbol: character. Optional. Symbol type (default "circle"). One of: "circle", "spike", "halfcircle".
k: numeric. Optional. Size of the largest symbol (default 50).
fixmax: numeric. Optional. Value corresponding to the symbol of size k. Useful for ensuring comparability between maps.
dodge: logical. Optional. Avoid symbol overlap (default FALSE, circle only).
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).
method: character. Optional. Classification method for choropleth (default "quantile"). One of: "quantile", "q6", "equal", "jenks", "msd", "geometric", "headtail", "pretty", "arithmetic", "nestedmeans".
nb: numeric. Optional. Number of classes (default 6).
breaks: numeric vector. Optional. Manual class breaks overriding nb and method.
colors: character or vector. Optional. Color palette or vector of colors from the Dicopal library. See https://observablehq.com/@neocartocnrs/dicopal-library
middle: logical. Optionnal Only for the MSD method: is the mean in a central class or not? (default FALSE)
sd: number. Only for the MSD method: the number of standard deviations taken into account (default 1)
reverse: logical. Optional. Reverse color palette (default FALSE).
missing: character or logical. Optional. Color for missing values (default "white").
legend: logical. Optional. Whether to display legends (default TRUE).
leg1_type: character. Optional. Symbol legend type (default "nested").
leg2_type: character. Optional. Choropleth legend type (default "vertical").
leg1_pos: numeric vector. Optional. Position of symbol legend (default c(10, 10)).
leg2_pos: numeric vector. Optional. Position of choropleth legend.
...: Additional parameters passed to rendering functions (e.g. strokeWidth). With leg1_ and leg2_ prefixes, you can configure the legends. For example: leg1_title, leg2_subtitle, leg1_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_propchoro(
  data = world, var1 = "pop", k = 25,
  leg1_values_round = 0, var2 = "gdppc",
  leg1_title = "Population",
  leg1_subtitle = "(million inh.)",
  leg1_values_factor = 1 / 1000000,
  leg2_values_round = 0,
  leg2_title = "GDP per inh.",
  colors = "Temps"
) |>
viz_render()