duckspatial (version 0.9.0)

ddbs_make_polygon: Creates polygons from linestring geometries

Description

Constructs polygon geometries from linestring geometries in a DuckDB table using the spatial extension. The input linestrings must be closed (first and last points must be identical). Returns the result as an sf object or creates a new table in the database.

Usage

ddbs_make_polygon(
  x,
  conn = NULL,
  name = NULL,
  crs = NULL,
  crs_column = "crs_duckspatial",
  overwrite = FALSE,
  quiet = FALSE
)

Value

an sf object or TRUE (invisibly) for table creation

Arguments

x

An sf spatial object. Alternatively, it can be a string with the name of a table with geometry column within the DuckDB database 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

crs

The coordinates reference system of the data. Specify if the data doesn't have a crs_column, and you know the CRS.

crs_column

a character string of length one specifying the column storing the CRS (created automatically by ddbs_write_vector). Set to NULL if absent.

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.

Examples

if (FALSE) {
## load packages
library(duckspatial)
library(sf)

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

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

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

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

## create polygon without using a connection
ddbs_make_polygon(ring_sf)
}