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Transform the coordinate reference system of geometries

Source: R/ddbs_ops_unary.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,
  crs = NULL,
  crs_column = "crs_duckspatial",
  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")

  • 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), the function returns the result as an sf object

crs

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

crs_column

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

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")
} # }