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Convert geometries to standard interchange formats

Source: R/ddbs_geom_conversion.R
ddbs_as_format.Rd

Convert spatial geometries to common interchange formats using DuckDB spatial serialization functions.

  • ddbs_as_text() – Convert geometries to Well-Known Text (WKT)

  • ddbs_as_wkb() – Convert geometries to Well-Known Binary (WKB)

  • ddbs_as_hexwkb() – Convert geometries to hexadecimal Well-Known Binary (HEXWKB)

  • ddbs_as_geojson() – Convert to GeoJSON (a FeatureCollection or one Feature per row)

Usage

ddbs_as_text(x, conn = NULL)

ddbs_as_wkb(x, conn = NULL)

ddbs_as_hexwkb(x, conn = NULL)

ddbs_as_geojson(x, conn = NULL, feature_collection = TRUE)

Arguments

x

Input spatial data. Can be:

  • A duckspatial_df object (lazy spatial data frame via dbplyr)

  • An sf object

  • A tbl_lazy from dbplyr

  • A character string naming a table/view in conn

Data is returned from this object.

conn

A connection object to a DuckDB database. If NULL, the function runs on a temporary DuckDB database.

feature_collection

Logical, only used by ddbs_as_geojson(). If TRUE (default), all rows are returned as a single GeoJSON FeatureCollection string. If FALSE, a character vector with one Feature string per row is returned.

Value

Depending on the function:

  • ddbs_as_text() returns a character vector of WKT geometries

  • ddbs_as_wkb() returns a list of raw vectors (binary WKB)

  • ddbs_as_hexwkb() returns a character vector of HEXWKB strings

  • ddbs_as_geojson() returns a single GeoJSON FeatureCollection string (class "geojson") when feature_collection = TRUE, or a character vector of Feature strings (one per row) when FALSE; non-geometry columns are included as feature properties

Details

These functions are thin wrappers around DuckDB spatial serialization functions (ST_AsText, ST_AsWKB, ST_AsHEXWKB, and ST_AsGeoJSON).

They are useful for exporting geometries into widely supported formats for interoperability with external spatial tools, databases, and web services.

Unlike the other serializers, which only encode the geometry, ddbs_as_geojson() produces complete GeoJSON Features: the geometry is placed in the geometry member and all remaining (non-geometry) columns are included as feature properties. By default the features are wrapped in a single FeatureCollection, the canonical GeoJSON artifact for writing .geojson files and feeding web services and mapping libraries.

Examples

if (FALSE) { # \dontrun{
library(duckspatial)

argentina_ddbs <- ddbs_open_dataset(
  system.file("spatial/argentina.geojson", package = "duckspatial")
)

ddbs_as_text(argentina_ddbs)
ddbs_as_wkb(argentina_ddbs)
ddbs_as_hexwkb(argentina_ddbs)

## a single FeatureCollection (default)
ddbs_as_geojson(argentina_ddbs)

## one Feature string per row
ddbs_as_geojson(argentina_ddbs, feature_collection = FALSE)
} # }