Adds an area column to @leaves, measured on an equal-area projection.
Arguments
- x
A
Geoscalewith geometry attached.- name
Name of the weight column to add.
- crs
Equal-area CRS used for the measurement. The default, World Cylindrical Equal Area, is global; a local equal-area projection is more accurate for a single region.
Value
A Geoscale with the area column added to @leaves and
registered in meta$weights.
Details
Areas are only as good as the geometry. Cartographic sources are generalised for display: measured on Natural Earth at 1:110m, Chile comes out 10.6% too large and Indonesia 3.2% too small against the same data at 1:10m. Use the finest geometry available, and treat the result as indicative rather than authoritative.
Geometry carrying no CRS is measured in its own planar units, with a warning: reprojection is impossible, but a synthetic or teaching map is still worth weighting by.