The dashboard can plot cluster case counts on a choropleth map by postcode
(or any other geographic unit you use), provided the optional sf
package is installed and geographic reference data is available. Without
either, the dashboard still works fine - it just falls back to a bar
chart of case counts by area instead of a map.
Usage
episodic_geo_overlay_resolve(
path = Sys.getenv("EPISODIC_GEO_DATA_OVERLAY", unset = NA)
)
episodic_geo_source_resolve(path = Sys.getenv("EPISODIC_GEO_DATA", unset = NA))Value
An sf object, or NULL if sf is not installed, no path is
set, or the file is missing or invalid.
Details
There is no default map. Point the EPISODIC_GEO_DATA environment
variable at your own .rds file (an sf object with a pc column
matching your case data's area codes, and a geometry column) to map
your own region. The Dutch postcode geometry bundled with the package
is used only by episodic_demo().
You can optionally add a second, purely visual layer of outlines - e.g.
province or municipality borders - drawn on top of the choropleth for
orientation, via EPISODIC_GEO_DATA_OVERLAY and
episodic_geo_overlay_resolve(). This layer carries no case counts, so
it only needs a geometry column.
Why there is no default map
A default map is a default country. Falling back to the Netherlands PC4 geometry bundled with the package would give a laboratory anywhere else a silent, confident map of the Netherlands with its own case counts joined onto whichever Dutch postcodes happened to share a number - postcode-like codes are four digits in a great many countries - and a plausible-looking wrong answer is worse than no answer. So there is no default: with nothing configured the map is simply absent, and the dashboard falls back to a bar chart of case counts by area, which is correct everywhere.
episodic_demo() sets EPISODIC_GEO_DATA to the bundled Netherlands
geometry itself, so the demo still shows a map.