Skip to contents

Spatial touches predicate

Source: R/ddbs_predicates.R
ddbs_touches.Rd

Tests if geometries in x touch geometries in y. Returns TRUE if geometries share a boundary but their interiors do not intersect.

Usage

ddbs_touches(
  x,
  y,
  conn = NULL,
  id_x = NULL,
  id_y = NULL,
  sparse = TRUE,
  quiet = FALSE
)

Arguments

x

An sf spatial object. Alternatively, it can be a string with the name of a table with geometry column within the DuckDB database conn. Data is returned from this object.

y

An sf spatial object. Alternatively, it can be a string with the name of a table with geometry column within the DuckDB database conn.

conn

A connection object to a DuckDB database. If NULL, the function runs on a temporary DuckDB database.

id_x

Character; optional name of the column in x whose values will be used to name the list elements. If NULL, integer row numbers of x are used.

id_y

Character; optional name of the column in y whose values will replace the integer indices returned in each element of the list.

sparse

A logical value. If TRUE, it returns a sparse index list. If FALSE, it returns a dense logical matrix.

quiet

A logical value. If TRUE, suppresses any informational messages. Defaults to FALSE.

Value

A list where each element contains indices (or IDs) of geometries in y that touch the corresponding geometry in x. See ddbs_predicate() for details.

Details

This is a convenience wrapper around ddbs_predicate() with predicate = "touches".

See also

ddbs_predicate() for other spatial predicates.

Examples


## load packages
library(dplyr)
library(duckspatial)
library(sf)

## read countries data, and rivers
countries_sf <- read_sf(system.file("spatial/countries.geojson", package = "duckspatial"))
countries_filter_sf <- countries_sf |> filter(CNTR_ID %in% c("PT", "ES", "FR", "IT"))

# Find neighboring countries
ddbs_touches(countries_filter_sf, countries_sf, id_x = "NAME_ENGL", id_y = "NAME_ENGL")
#> ✔ Query successful
#> $Spain
#> [1] "Andorra"   "Gibraltar" "France"    "Portugal" 
#> 
#> $France
#> [1] "Andorra"     "Belgium"     "Switzerland" "Spain"       "Italy"      
#> [6] "Germany"     "Luxembourg"  "Monaco"     
#> 
#> $Italy
#> [1] "Austria"      "Switzerland"  "France"       "Vatican City" "Slovenia"    
#> [6] "San Marino"  
#> 
#> $Portugal
#> [1] "Spain"
#>