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Transform coordinate reference system of geometries

Source: R/ddbs_ops_unary.R
ddbs_transform.Rd

Transforms geometries from a DuckDB table to a different coordinate reference system using the spatial extension. Works similarly to sf::st_transform(). Returns the result as an sf object or creates a new table in the database.

Usage

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

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.

y

Target CRS. Can be:

  • A character string with EPSG code (e.g., "EPSG:4326")

  • An sf object (uses its CRS)

  • Name of a DuckDB table (uses its CRS)

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.

Value

an sf object or TRUE (invisibly) for table creation

Examples

if (FALSE) { # \dontrun{
## 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")

## transform to different CRS using EPSG code
ddbs_transform("argentina", "EPSG:3857", conn)

## transform to match CRS of another sf object
argentina_3857_sf <- st_transform(argentina_sf, "EPSG:3857")
ddbs_write_vector(conn, argentina_3857_sf, "argentina_3857")
ddbs_transform("argentina", argentina_3857_sf, conn)

## transform to match CRS of another DuckDB table
ddbs_transform("argentina", "argentina_3857", conn)

## transform without using a connection
ddbs_transform(argentina_sf, "EPSG:3857")
} # }