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Geometry binary operations

Source: R/ddbs_ops_binary.R
ddbs_binary_funs.Rd

Perform geometric set operations between two sets of geometries.

Usage

ddbs_intersection(
  x,
  y,
  conn = NULL,
  conn_x = NULL,
  conn_y = NULL,
  name = NULL,
  crs = NULL,
  crs_column = "crs_duckspatial",
  mode = NULL,
  overwrite = FALSE,
  quiet = FALSE
)

ddbs_difference(
  x,
  y,
  conn = NULL,
  conn_x = NULL,
  conn_y = NULL,
  name = NULL,
  crs = NULL,
  crs_column = "crs_duckspatial",
  mode = NULL,
  overwrite = FALSE,
  quiet = FALSE
)

ddbs_sym_difference(
  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

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

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).

Details

These functions perform different geometric set operations:

ddbs_intersection

Returns the geometric intersection of two sets of geometries, producing the area, line, or point shared by both.

ddbs_difference

Returns the portion of the first geometry that does not overlap with the second geometry.

ddbs_sym_difference

Returns the portions of both geometries that do not overlap with each other. Equivalent to (A - B) UNION (B - A).

Examples

if (FALSE) { # \dontrun{
library(duckspatial)
library(sf)

# Create two overlapping polygons for testing
poly1 <- st_polygon(list(matrix(c(
  0, 0,
  4, 0,
  4, 4,
  0, 4,
  0, 0
), ncol = 2, byrow = TRUE)))

poly2 <- st_polygon(list(matrix(c(
  2, 2,
  6, 2,
  6, 6,
  2, 6,
  2, 2
), ncol = 2, byrow = TRUE)))

x <- st_sf(id = 1, geometry = st_sfc(poly1), crs = 4326)
y <- st_sf(id = 2, geometry = st_sfc(poly2), crs = 4326)

# Visualize the input polygons
plot(st_geometry(x), col = "lightblue", main = "Input Polygons")
plot(st_geometry(y), col = "lightcoral", add = TRUE, alpha = 0.5)

# Intersection: only the overlapping area (2,2 to 4,4)
result_intersect <- ddbs_intersection(x, y)
plot(st_geometry(result_intersect), col = "purple", 
     main = "Intersection")

# Difference: part of x not in y (L-shaped area)
result_diff <- ddbs_difference(x, y)
plot(st_geometry(result_diff), col = "lightblue", 
     main = "Difference (x - y)")

# Symmetric Difference: parts of both that don't overlap
result_symdiff <- ddbs_sym_difference(x, y)
plot(st_geometry(result_symdiff), col = "orange", 
     main = "Symmetric Difference")

# Using with database connection
conn <- ddbs_create_conn(dbdir = "memory")

ddbs_write_vector(conn, x, "poly_x")
ddbs_write_vector(conn, y, "poly_y")

# Perform operations with connection
ddbs_intersection("poly_x", "poly_y", conn)
ddbs_difference("poly_x", "poly_y", conn)
ddbs_sym_difference("poly_x", "poly_y", conn)

# Save results to database table
ddbs_difference("poly_x", "poly_y", conn, name = "diff_result")
} # }