Get projection from NetCDF-CF Grid Mapping

Takes NetCDF-CF grid mapping attributes and returns a proj4 string.

nc_gm_to_prj(x)

# S3 method for data.frame
nc_gm_to_prj(x)

# S3 method for list
nc_gm_to_prj(x)

Arguments

x

list or data.frame of attributes of the grid mapping variable as returned by ncdf or ncdf4's get attributes functions or ncmeta's nc_grid_mapping_atts.

Value

A proj4 string.

Details

The WGS84 datum is used as a default if one os not provided in the grid mapping.

If only a semi_major axis is provided, a sperical earth is assumed.

References

1. https://en.wikibooks.org/wiki/PROJ.4

2. https://trac.osgeo.org/gdal/wiki/NetCDF_ProjectionTestingStatus

3. http://cfconventions.org/cf-conventions/cf-conventions.html#appendix-grid-mappings

Examples

crs <- list(grid_mapping_name="latitude_longitude",
            longitude_of_prime_meridian = 0,
            semi_major_axis = 6378137,
            inverse_flattening = 298)
nc_gm_to_prj(crs)