Spatial Filter — ddbs_filter • duckspatial

Filters data spatially based on a spatial predicate

Usage

ddbs_filter(
  conn,
  x,
  y,
  name = NULL,
  predicate = "intersection",
  crs = NULL,
  crs_column = "crs_duckspatial",
  overwrite = FALSE
)

Arguments

conn: a connection object to a DuckDB database
x: a table with geometry column within the DuckDB database. Data is returned from this object
y: a table with geometry column within the 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 it's NULL (the default), it will return the result as an sf object
predicate: geometry predicate to use for filtering the data
crs: the coordinates reference system of the data. Specify if the data doesn't have 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: whether to overwrite the existing table if it exists. Ignored when name is NULL

Value

an sf object or TRUE (invisibly) for table creation

Examples

# \donttest{
## load packages
library(duckdb)
library(duckspatial)
library(sf)

## database setup
conn <- dbConnect(duckdb())
ddbs_install(conn)
#> ℹ spatial extension version <2905968> is already installed in this database
ddbs_load(conn)
#> ✔ Spatial extension loaded

## read data
countries_sf <- st_read(system.file("spatial/countries.geojson", package = "duckspatial"))
#> Reading layer `countries' from data source 
#>   `/home/runner/work/_temp/Library/duckspatial/spatial/countries.geojson' 
#>   using driver `GeoJSON'
#> Simple feature collection with 257 features and 6 fields
#> Geometry type: POLYGON
#> Dimension:     XY
#> Bounding box:  xmin: -178.9125 ymin: -89.9 xmax: 180 ymax: 83.65187
#> Geodetic CRS:  WGS 84
argentina_sf <- st_read(system.file("spatial/argentina.geojson", package = "duckspatial"))
#> Reading layer `argentina' from data source 
#>   `/home/runner/work/_temp/Library/duckspatial/spatial/argentina.geojson' 
#>   using driver `GeoJSON'
#> Simple feature collection with 1 feature and 6 fields
#> Geometry type: POLYGON
#> Dimension:     XY
#> Bounding box:  xmin: -73.52455 ymin: -52.39755 xmax: -53.62409 ymax: -21.81793
#> Geodetic CRS:  WGS 84

## store in duckdb
ddbs_write_vector(conn, countries_sf, "countries")
#> ✔ Table countries successfully imported
ddbs_write_vector(conn, argentina_sf, "argentina")
#> ✔ Table argentina successfully imported

## filter countries touching argentina
ddbs_filter(conn, "countries", "argentina", predicate = "touches")
#> ✔ Query successful
#> Simple feature collection with 5 features and 6 fields
#> Geometry type: POLYGON
#> Dimension:     XY
#> Bounding box:  xmin: -75.58129 ymin: -55.58443 xmax: -34.84846 ymax: 5.25818
#> Geodetic CRS:  WGS 84
#>   CNTR_ID NAME_ENGL ISO3_CODE                       CNTR_NAME FID       date
#> 1      BO   Bolivia       BOL Wuliwya-Volívia-Bulivya-Bolivia  BO 2021-01-01
#> 2      BR    Brazil       BRA                          Brasil  BR 2021-01-01
#> 3      CL     Chile       CHL                           Chile  CL 2021-01-01
#> 4      PY  Paraguay       PRY               Paraguay-Paraguái  PY 2021-01-01
#> 5      UY   Uruguay       URY                         Uruguay  UY 2021-01-01
#>                         geometry
#> 1 POLYGON ((-58.16346 -20.162...
#> 2 POLYGON ((-56.47737 1.94594...
#> 3 POLYGON ((-67.1775 -22.8046...
#> 4 POLYGON ((-58.16346 -20.162...
#> 5 POLYGON ((-53.37795 -33.750...
# }