Keep features that touch a mask layer

Returns the rows of x whose geometries intersect (touch) any geometry in y, using sf::st_intersects(). No clipping is performed: geometries are returned unchanged. Useful for selecting features inside or crossing a boundary without computing actual geometric intersections.

intersect_filter_touch(x, y, repair = TRUE)

Arguments

x

An sf::sf object.

y

An sf::sf mask layer.

repair

If TRUE, apply sf::st_make_valid() to x and y first (warnings are suppressed per call). Default TRUE.

Value

An sf::sf subset of x containing only features that touch y, preserving the original geometry and attributes of x.

Details

A feature is kept when lengths(st_intersects(x, y)) is greater than zero, i.e. when it shares at least one point with any feature in y. This is the lightest-touch selection strategy: it does not reproject, clip, or measure overlap area. Both layers must share the same CRS (or have CRS that sf::st_intersects() can reconcile); transform them beforehand if needed.

See also

Other geo-tools: intersect_mask_filter_area(), quick_map(), view_mapview_from_path()

Examples

# \donttest{
crs_pl <- sf::st_crs(3857)
ring <- matrix(
  c(0, 0, 1e6, 0, 1e6, 1e6, 0, 1e6, 0, 0),
  ncol = 2L,
  byrow = TRUE
)
y <- sf::st_sf(geometry = sf::st_sfc(sf::st_polygon(list(ring)), crs = crs_pl))
inner <- matrix(
  c(1e5, 1e5, 9e5, 1e5, 9e5, 9e5, 1e5, 9e5, 1e5, 1e5),
  ncol = 2L,
  byrow = TRUE
)
outside <- matrix(
  c(2e6, 2e6, 3e6, 2e6, 3e6, 3e6, 2e6, 3e6, 2e6, 2e6),
  ncol = 2L,
  byrow = TRUE
)
x <- sf::st_sf(
  id = c("in", "out"),
  geometry = sf::st_sfc(
    sf::st_polygon(list(inner)),
    sf::st_polygon(list(outside)),
    crs = crs_pl
  )
)
intersect_filter_touch(x, y)
#> Simple feature collection with 1 feature and 1 field
#> Geometry type: POLYGON
#> Dimension:     XY
#> Bounding box:  xmin: 1e+05 ymin: 1e+05 xmax: 9e+05 ymax: 9e+05
#> Projected CRS: WGS 84 / Pseudo-Mercator
#>   id                       geometry
#> 1 in POLYGON ((1e+05 1e+05, 1e+0...
# }