Spike map (heights at country centroids) — spike

The classic "population spikes" display: a triangular spike at each country centroid whose height encodes the value. Like bubble_map() it is the honest idiom for totals, with a different visual trade-off: spikes overplot less in dense regions (Europe, the Caribbean) because they only grow upward. Uses the polygon backend, so it needs no extra package.

Usage

spike_map(
  data,
  height,
  max_height = 20,
  width = 1.6,
  color = "#B2182B",
  alpha = 0.65,
  projection = "equal_earth",
  footnote = "auto"
)

Arguments

data: A country-level frame with iso3c and the height column.
height: The column controlling spike height (unquoted).
max_height: Height of the tallest spike, in degrees of latitude (default 20). On a projected map that is a ground distance (one degree is about 111 km) laid out in the projection's own units, so every spike uses the same scale wherever it stands; with projection = "none" or "orthographic" it is in the map's degrees.
width: Base width of each spike, in degrees of longitude at the equator (default 1.6), measured the same way.
color: Spike colour (default a warm red).
alpha: Spike fill transparency.
projection: Map projection, as in world_map() (default "equal_earth").
footnote: The caption: "auto" (default) states the coverage and source, a string is used as given, FALSE adds nothing. See world_map().

Value

A ggplot object.

Examples

# \donttest{
spike_map(countryatlas::world_snapshot$countries, population)
#> Warning: population: 1 country is not drawn -- no bundled centroid.
#> • "GIB"
#> ℹ They are counted as missing in the caption and in `map_provenance()`.

# }