Why do the Natural Earth shapefiles like ne_110m_countries_admin_0.shp have a geometry-type POLYGON, while it should be MULTIPOLYGON (at least when I understand Understanding difference between Polygon and Multipolygon for shapefiles in QGIS? correct. E.g. USA48 + Alaska + Hawaii is Multipolygon)
Shapefile specification does not have a geometry type
Multipolygon. The closest one is
Polygon (with Z or M added). However, the USA is a multi-part polygon indeed meaning that it is represented as a single row in the shapefile yet the geometry itself consists of a few parts.
arcpy code run on shapefile:
> c = [f for f in arcpy.da.SearchCursor("countries", "SHAPE@")] > c.isMultipart` True > c.WKT[:30] u'MULTIPOLYGON (((-155.581347656'
However, if you import the shapefile into some other more sophisticated storage format, such as PostGIS, the polygons would be stored using
Multipolygon geometry type:
Importing with configuration: ne_50m_admin_0_countries, public, geom, C:\GIS\Datasets\ne_50m_admin_0_countries\ne_50m_admin_0_countries.shp, mode=c, dump=1, simple=0, geography=0, index=1, shape=1, srid=4326 Shapefile type: Polygon PostGIS type: MULTIPOLYGON Shapefile import completed.
SQL in PostGIS:
select ST_AsText(Geom) from ne_50m_admin_0_countries where sov_a3 = 'US1' and type = 'Country'