Half-circle layer — viz_halfcircle • geoviz

The viz_halfcircle function draws rotatable half-circles on the map from a spatial data frame or from a single position. It can be used to represent values with semi-circular proportional symbols.

Usage

viz_halfcircle(
  map,
  data = NULL,
  id = NULL,
  pos = c(0, 0),
  dx = 0,
  dy = 0,
  angle = 0,
  r = 10,
  innerRadius = 0,
  cornerRadius = 2,
  k = 50,
  fixmax = NULL,
  sort = NULL,
  descending = NULL,
  coords = "geo",
  fill = NULL,
  stroke = NULL,
  tip = FALSE,
  ...
)

Arguments

map: A geoviz map created with viz_create.
data: object. Optional. A spatial data frame.
id: character. Optional. Unique layer id.
pos: numeric vector. Optional. Position of a single half-circle (default c(0, 0)).
dx: numeric. Optional. Horizontal shift (default 0).
dy: numeric. Optional. Vertical shift (default 0).
angle: numeric. Optional. Rotation angle in degrees (default 0).
r: numeric or character. Optional. Outer radius (default 10). Can be a fixed value or the name of a field containing numerical values.
innerRadius: numeric. Optional. Inner radius (default 0).
cornerRadius: numeric. Optional. Corner radius (default 2).
k: numeric. Optional. Radius of the largest half-circle (default 50).
fixmax: numeric. Optional. Value corresponding to the half-circle of radius k. Useful to ensure comparability between maps.
sort: character or function. Optional. Field name or function to sort half-circles.
descending: logical. Optional. Sorting order.
coords: character. Optional. Coordinate system (default "geo"). Use "svg" if coordinates are already expressed in the SVG coordinate space.
fill: character or function. Optional. Fill color.
stroke: character or function. Optional. Stroke color.
tip: logical or function. Optional. Tooltip definition (default FALSE). Use TRUE to display all fields.
...: Additional SVG attributes (e.g. strokeDasharray, strokeWidth, opacity, strokeLinecap, etc.).

Examples

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

viz_create(projection = "EqualEarth") |>
viz_path(datum = world, fill = "#f1f3f5") |>
viz_halfcircle(data = world, r = 30, fill = "#38896F") |>
viz_render()