A lightweight GDAL API package for R.
The following options can be set to control global behaviour.
Sys.getenv("vapour.sql.dialect") | the current SQL dialect in use |
The SQL dialect can be set to "" (empty string), "OGRSQL", or "SQLITE".
The empty string indicates that the native dialect will be used, see OGRSQL and SQLITE for GDAL, accessed 2022-11-11 and the GDAL_DMD_SUPPORTED_SQL_DIALECTS development documentation (since GDAL 3.6).
Setting "NATIVE" as an alias for "" is quite recent and has not been tested with vapour, similarly no testing has been done with non OGRSQL-native or SQLITE-native drivers yet.
Provides low-level access to 'GDAL' functionality for R packages. The aim is to minimize the level of interpretation put on the 'GDAL' facilities, to enable direct use of it for a variety of purposes. 'GDAL' is the 'Geospatial Data Abstraction Library' a translator for raster and vector geospatial data formats that presents a single raster abstract data model and single vector abstract data model to the calling application for all supported formats https://gdal.org/.
Lightweight means we access parts of the GDAL API as near as possible to their native usage. GDAL is not a lightweight library, but provide a very nice abstraction over format details for a very large number of different formats.
Functions for raster and vector sources are included.
vapour_all_drivers | list of all available drivers, with type and features |
vapour_driver | report short name of driver that will be used for a data source |
vapour_gdal_version | report version of GDAL in use |
vapour_srs_wkt | produce WKT projection string from various projection string inputs |
vapour_vsi_list | report contents of VSI sources |
vapour_raster_gcp | return internal ground control points, if present |
vapour_raster_info | structural metadata of a source |
vapour_read_raster | read data direct from a window of a raster band source |
vapour_sds_names | list individual raster sources in a source containing subdatasets |
vapour_warp_raster | read data direct from a raster source into a specific window |
vapour_driver | report name of the driver used for a given source |
vapour_geom_name | report attribute name of geometry |
vapour_geom_summary | report simple properties of each feature geometry |
vapour_layer_names | list names of vector layers in a data source |
vapour_layer_info | list of data source, driver, layer name/s, fields, feature count, projection |
vapour_read_extent | read the extent, or bounding box, of geometries in a layer |
vapour_read_fields | read attributes of features in a layer, the columnar data associated with each geometry |
vapour_read_geometry | read geometry in binary (blob, WKB) form |
vapour_read_geometry_ia | read geometry by index, arbitrary |
vapour_read_geometry_ij | read geometry by sequential index, i to j |
vapour_read_geometry_text | read geometry in text form, various formats |
vapour_read_names | read the 'names' of features in a layer, the 'FID' |
vapour_read_type | read the GDAL types of attributes |
vapour_report_fields | report internal type of each attribute by name |
As far as possible vapour aims to minimize the level of interpretation provided for the functions, so that developers can choose how things are implemented. Functions return raw lists or vectors rather than data frames or classed types.