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Transform the coordinate reference system of geometries

Source: R/ddbs_crs.R
ddbs_transform.Rd

Converts geometries to a different coordinate reference system (CRS), updating their coordinates accordingly.

Usage

ddbs_transform(
  x,
  y,
  conn = NULL,
  conn_x = NULL,
  conn_y = 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.

y

Target CRS. Can be:

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

  • A crs object created with sf::st_crs

  • 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.

conn_x

A DBIConnection object to a DuckDB database for the input x. If NULL (default), it is resolved from conn or extracted from x.

conn_y

A DBIConnection object to a DuckDB database for the input y. If NULL (default), it is resolved from conn or extracted from y.

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), no table is written and the result is returned as a duckspatial_df or sf object, depending on mode

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).

Examples

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

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

## transform to match CRS of another object
argentina_3857_ddbs <- ddbs_transform(argentina_ddbs, "EPSG:3857")
ddbs_write_vector(conn, argentina_3857_ddbs, "argentina_3857")
ddbs_transform("argentina", argentina_3857_ddbs, conn)

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

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