Metadata and CRS

Spatial tables need two kinds of context: which columns contain geometries and which coordinate reference system (CRS) describes their coordinates. GeoDataFrames stores both as table metadata. That keeps an ordinary DataFrame interoperable while giving readers and writers a single source for spatial defaults.

Assigning a CRS records the meaning of coordinates already in a table. setcrs! changes that label only; it does not alter any coordinates. Use it when the coordinates already use a known CRS but the table lacks that information.

Transforming a CRS changes coordinate values to express the same locations in another system. reproject returns a transformed copy, and reproject! replaces the geometry coordinates in place. The source CRS must be correct before either transformation can be meaningful.

The metadata reference specifies the stored metadata and its accessors. Use manage geometry metadata to assign geometry metadata and reproject data to transform coordinates.