Small-multiple choropleths — facet

Facet a choropleth into small multiples (one panel per group or per year) – the static counterpart to animate_world(), for print and side-by-side comparison. Builds a world_map() and facets it on facet.

Usage

facet_map(
  data,
  fill,
  facet,
  ncol = NULL,
  breaks_by = c("pooled", "panel"),
  ...
)

Arguments

data: A map-ready frame (polygon or sf) containing the facet column.
fill: The fill column (unquoted).
facet: The faceting column (unquoted; e.g. year or continent).
ncol: Number of facet columns (passed to ggplot2::facet_wrap()).
breaks_by: "pooled" (default) classifies every panel together, with one set of breaks, so the same colour means the same value in every panel and the panels can be compared. "panel" classifies each panel on its own values – each country's class within its own year – and the legend says so; colours are then comparable as ranks, not as values.
...: Passed to world_map() (e.g. style, projection).

Value

A faceted ggplot object.

Backend

Either backend, as world_map(): the frame decides, and both draw in projection (Equal Earth by default).

Examples

# \donttest{
snap <- countryatlas::world_snapshot$countries
mapdf <- attach_geometry(snap, geometry = "polygon")
facet_map(mapdf, gdp_per_capita, continent, style = "quantile")

# }