Keep the rows of a data frame that relate to another spatially

Filters x down to the rows whose geometry relates to any row of y. Unlike ga_join(), it does not attach the columns of y.

Usage

ga_filter(x, y, predicate = ga_sparse_intersects, ...)

Arguments

x, y

data frames, each with one GeoArrow geometry column

predicate

a sparse predicate, by default ga_sparse_intersects()

Value

an Arrow table holding the rows of x that matched

Details

ga_filter() keeps a row of x when the predicate finds at least one match for it in y, so ga_filter(sites, counties, ga_sparse_within) keeps the sites that fall in any county. ga_filter() matches ST_Filter(), and returns the same rows as ga_join(x, y, predicate, left = FALSE) would, without the columns of y and without repeating rows of x.

See also

Other topology: ga_contains(), ga_coordinate_position(), ga_dimension(), ga_equals_exact(), ga_is_empty(), ga_join(), ga_relate(), ga_sparse_equals_exact(), ga_sparse_intersects(), ga_sparse_pairs()

Examples

nc <- as.data.frame(read_shapefile(
  system.file("shape/nc.shp", package = "sf")
))
sites <- data.frame(
  site = c("a", "b", "c"),
  geometry = geoarrow::as_geoarrow_vctr(
    ga_point(c(-78.6, -80.8, 0), c(35.8, 35.2, 0))
  )
)

# the third site is in the Atlantic, so ga_filter() drops it
ga_filter(sites, nc, ga_sparse_within)
#> Table
#> 2 rows x 2 columns
#> $site <string>
#> $geometry: geoarrow.point <crs <unspecified>>
#> 
#> See $metadata for additional Schema metadata