ddbs_make_polygon: Create a polygon from a single closed linestring

In duckspatial: R Interface to 'DuckDB' Database with Spatial Extension

Create a polygon from a single closed linestring

Description

Converts a single closed linestring geometry into a polygon. The linestring must be closed (first and last points identical). Does not work with MULTILINESTRING inputs - use ddbs_polygonize() or ddbs_build_area() instead.

Usage

ddbs_make_polygon(
  x,
  conn = NULL,
  name = NULL,
  mode = NULL,
  overwrite = FALSE,
  quiet = FALSE
)

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.
name	A character string of length one specifying the name of the table, or a character string of length two specifying the schema and table names. If NULL (the default), the function returns the result as an sf object
mode	Character. Controls the return type. Options: "duckspatial" (default): Lazy spatial data frame backed by dbplyr/DuckDB "sf": Eagerly collected sf object (uses memory) Can be set globally via ddbs_options(mode = "...") or per-function via this argument. Per-function overrides global setting.
overwrite	Boolean. whether to overwrite the existing table if it exists. Defaults to FALSE. This argument is ignored when name is NULL.
quiet	A logical value. If TRUE, suppresses any informational messages. Defaults to FALSE.

Value

Depends on the mode argument (or global preference set by ddbs_options):

• duckspatial (default): A duckspatial_df (lazy spatial data frame) backed by dbplyr/DuckDB.

• sf: An eagerly collected object in R memory, that will return the same data type as the sf equivalent (e.g. sf or units vector).

When name is provided, the result is also written as a table or view in DuckDB and the function returns TRUE (invisibly).

See Also

ddbs_polygonize(), ddbs_build_area()

Other polygon construction: ddbs_build_area(), ddbs_polygonize()

Examples

## Not run: 
## load package
library(duckspatial)

# create a duckdb database in memory (with spatial extension)
conn <- ddbs_create_conn(dbdir = "memory")

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

## store in duckdb
ddbs_write_vector(conn, argentina_ddbs, "argentina")

## extract exterior ring as linestring, then convert back to polygon
ring_ddbs <- ddbs_exterior_ring(conn = conn, "argentina")
ddbs_make_polygon(conn = conn, ring_ddbs, name = "argentina_poly")

## create polygon without using a connection
ddbs_make_polygon(ring_ddbs)

## End(Not run)

duckspatial documentation built on June 22, 2026, 9:08 a.m.