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Perform a spatial filter

Source: R/ddbs_filter.R
ddbs_filter.Rd

Filters geometries based on a spatial relationship with another geometry, such as intersection, containment, or proximity.

Usage

ddbs_filter(
  x,
  y,
  predicate = "intersects",
  conn = NULL,
  conn_x = NULL,
  conn_y = NULL,
  name = NULL,
  distance = 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

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

predicate

A geometry predicate function. Defaults to intersects, a wrapper of ST_Intersects. See details for other options.

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

distance

a numeric value specifying the distance for ST_DWithin. The units should be specified in meters

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

Spatial Join Predicates:

A spatial predicate is really just a function that evaluates some spatial relation between two geometries and returns true or false, e.g., “does a contain b” or “is a within distance x of b”. Here is a quick overview of the most commonly used ones, taking two geometries a and b:

  • "ST_Intersects": Whether a intersects b

  • "ST_Contains": Whether a contains b

  • "ST_ContainsProperly": Whether a contains b without b touching a's boundary

  • "ST_Within": Whether a is within b

  • "ST_Overlaps": Whether a overlaps b

  • "ST_Touches": Whether a touches b

  • "ST_Equals": Whether a is equal to b

  • "ST_Crosses": Whether a crosses b

  • "ST_Covers": Whether a covers b

  • "ST_CoveredBy": Whether a is covered by b

  • "ST_DWithin": x) Whether a is within distance x of b

Examples

if (FALSE) { # \dontrun{
# RECOMMENDED: Efficient lazy workflow using ddbs_open_dataset
library(duckspatial)

# Load data directly as lazy spatial data frames (CRS auto-detected)
countries <- ddbs_open_dataset(
  system.file("spatial/countries.geojson", package = "duckspatial")
)

argentina <- ddbs_open_dataset(
  system.file("spatial/argentina.geojson", package = "duckspatial")
)

# Lazy filter - computation stays in DuckDB
neighbors <- ddbs_filter(countries, argentina, predicate = "touches")

# Collect to sf when needed
neighbors_sf <- dplyr::collect(neighbors) |> sf::st_as_sf()


# Alternative: using sf objects directly (legacy compatibility)
library(sf)

countries_sf <- st_read(system.file("spatial/countries.geojson", package = "duckspatial"))
argentina_sf <- st_read(system.file("spatial/argentina.geojson", package = "duckspatial"))

result <- ddbs_filter(countries_sf, argentina_sf, predicate = "touches")


# Alternative: using table names in a duckdb connection
conn <- ddbs_create_conn(dbdir = "memory")

ddbs_write_table(conn, countries_sf, "countries")
ddbs_write_table(conn, argentina_sf, "argentina")

ddbs_filter(conn = conn, "countries", "argentina", predicate = "touches")
} # }