Check validity or make an invalid geometry valid

Checks whether a geometry is valid, or makes an invalid geometry valid

Usage

st_is_valid(x, ...)

# S3 method for class 'sfc'
st_is_valid(x, ..., NA_on_exception = TRUE, reason = FALSE)

# S3 method for class 'sf'
st_is_valid(x, ...)

# S3 method for class 'sfg'
st_is_valid(x, ...)

st_make_valid(x, ...)

# S3 method for class 'sfg'
st_make_valid(x, ...)

# S3 method for class 'sfc'
st_make_valid(
  x,
  ...,
  oriented = FALSE,
  s2_options = s2::s2_options(snap = s2::s2_snap_precision(1e+07), ...),
  geos_method = "valid_structure",
  geos_keep_collapsed = TRUE
)

Arguments

x: object of class sfg, sfc or sf
...: passed on to s2_options
NA_on_exception: logical; if TRUE, for polygons that would otherwise raise a GEOS error (exception, e.g. for a POLYGON having more than zero but less than 4 points, or a LINESTRING having one point) return an NA rather than raising an error, and suppress warning messages (e.g. about self-intersection); if FALSE, regular GEOS errors and warnings will be emitted.
reason: logical; if TRUE, return a character with, for each geometry, the reason for invalidity, NA on exception, or "Valid Geometry" otherwise.
oriented: logical; only relevant if st_is_longlat(x) is TRUE; see s2
s2_options: only relevant if st_is_longlat(x) is TRUE; options for s2_rebuild, see s2_options and Details.
geos_method: character; either "valid_linework" (Original method, combines all rings into a set of noded lines and then extracts valid polygons from that linework) or "valid_structure" (Structured method, first makes all rings valid then merges shells and subtracts holes from shells to generate valid result. Assumes that holes and shells are correctly categorized.) (requires GEOS >= 3.10.1)
geos_keep_collapsed: logical; When this parameter is not set to FALSE, the "valid_structure" method will keep any component that has collapsed into a lower dimensionality. For example, a ring collapsing to a line, or a line collapsing to a point (requires GEOS >= 3.10.1)

Value

st_is_valid returns a logical vector indicating for each geometries of x whether it is valid. st_make_valid returns an object with a topologically valid geometry.

Object of the same class as x

Details

For projected geometries, st_make_valid uses the lwgeom_makevalid method also used by the PostGIS command ST_makevalid if the GEOS version linked to is smaller than 3.8.0, and otherwise the version shipped in GEOS; for geometries having ellipsoidal coordinates s2::s2_rebuild is being used.

if s2_options is not specified and x has a non-zero precision set, then this precision value will be used as the value in s2_snap_precision, passed on to s2_options, rather than the 1e7 default.

Examples

p1 = st_as_sfc("POLYGON((0 0, 0 10, 10 0, 10 10, 0 0))")
st_is_valid(p1)
#> [1] FALSE
st_is_valid(st_sfc(st_point(0:1), p1[[1]]), reason = TRUE)
#> [1] "Valid Geometry"         "Self-intersection[5 5]"
library(sf)
x = st_sfc(st_polygon(list(rbind(c(0,0),c(0.5,0),c(0.5,0.5),c(0.5,0),c(1,0),c(1,1),c(0,1),c(0,0)))))
suppressWarnings(st_is_valid(x))
#> [1] FALSE
y = st_make_valid(x)
st_is_valid(y)
#> [1] TRUE
y %>% st_cast()
#> Geometry set for 1 feature 
#> Geometry type: POLYGON
#> Dimension:     XY
#> Bounding box:  xmin: 0 ymin: 0 xmax: 1 ymax: 1
#> CRS:           NA
#> POLYGON ((0 0, 0 1, 1 1, 1 0, 0.5 0, 0 0))