| Version: | 0.2-14 |
| Title: | Bindings to Selected 'liblwgeom' Functions for Simple Features |
| Description: | Access to selected functions found in 'liblwgeom' https://github.com/postgis/postgis/tree/master/liblwgeom, the light-weight geometry library used by 'PostGIS' http://postgis.net/. |
| Depends: | R (≥ 3.3.0) |
| Imports: | Rcpp, units, sf (≥ 1.0-15) |
| Suggests: | covr, sp, geosphere, testthat |
| LinkingTo: | Rcpp, sf (≥ 0.6-0) |
| SystemRequirements: | GEOS (>= 3.5.0), PROJ (>= 4.8.0), sqlite3 |
| License: | GPL-2 |
| Copyright: | file COPYRIGHTS |
| Encoding: | UTF-8 |
| URL: | https://r-spatial.github.io/lwgeom/, https://github.com/r-spatial/lwgeom |
| BugReports: | https://github.com/r-spatial/lwgeom/issues |
| Collate: | init.R RcppExports.R geohash.R split.R subdivide.R valid.R transform.R bounding_circle.R bearing.R snap_to_grid.R startpoint.R twkb.R perimeter.R clockwise.R geod.R wkt.R wrap_x.R |
| RoxygenNote: | 7.3.1 |
| NeedsCompilation: | yes |
| Packaged: | 2024-02-21 14:39:21 UTC; edzer |
| Author: | Edzer Pebesma 
[aut, cre],
Colin Rundel [ctb],
Andy Teucher [ctb],
liblwgeom developers [cph] |
| Maintainer: | Edzer Pebesma <edzer.pebesma@uni-muenster.de> |
| Repository: | CRAN |
| Date/Publication: | 2024-02-21 21:30:02 UTC |
Generate the minimum bounding circle
Description
Generate the minimum bounding circle
Usage
st_minimum_bounding_circle(x, nQuadSegs = 30)
Arguments
x |
object of class |
nQuadSegs |
number of segments per quadrant (passed to |
Details
st_minimum_bounding_circle uses the lwgeom_calculate_mbc method also used by the PostGIS command ST_MinimumBoundingCircle.
Value
Object of the same class as x
Examples
library(sf)
x = st_multipoint(matrix(c(0,1,0,1),2,2))
y = st_multipoint(matrix(c(0,0,1,0,1,1),3,2))
mbcx = st_minimum_bounding_circle(x)
mbcy = st_minimum_bounding_circle(y)
if (.Platform$OS.type != "windows") {
plot(mbcx, axes=TRUE); plot(x, add=TRUE)
plot(mbcy, axes=TRUE); plot(y, add=TRUE)
}
nc = st_read(system.file("gpkg/nc.gpkg", package="sf"))
state = st_union(st_geometry(nc))
if (.Platform$OS.type != "windows") {
plot(st_minimum_bounding_circle(state), asp=1)
plot(state, add=TRUE)
}
liblwgeom geodetic functions
Description
liblwgeom geodetic functions for length, area, segmentizing, covers
Usage
st_geod_area(x)
st_geod_length(x)
st_geod_segmentize(x, max_seg_length)
st_geod_covers(x, y, sparse = TRUE)
st_geod_covered_by(x, y, sparse = TRUE)
st_geod_distance(x, y, tolerance = 0, sparse = FALSE)
Arguments
x |
object of class |
max_seg_length |
segment length in degree, radians, or as a length unit (e.g., m) |
y |
object of class |
sparse |
logical; if |
tolerance |
double or length |
Details
st_area will give an error message when the area spans the equator and lwgeom is linked to a proj.4 version older than 4.9.0 (see lwgeom_extSoftVersion)
longitude coordinates returned are rescaled to [-180,180)
Note
this function should is used by st_distance, do not use it directly
Examples
library(sf)
nc = st_read(system.file("gpkg/nc.gpkg", package="sf"))
st_geod_area(nc[1:3,])
# st_area(nc[1:3,])
l = st_sfc(st_linestring(rbind(c(7,52), c(8,53))), crs = 4326)
st_geod_length(l)
library(units)
pol = st_polygon(list(rbind(c(0,0), c(0,60), c(60,60), c(0,0))))
x = st_sfc(pol, crs = 4326)
seg = st_geod_segmentize(x[1], set_units(10, km))
plot(seg, graticule = TRUE, axes = TRUE)
pole = st_polygon(list(rbind(c(0,80), c(120,80), c(240,80), c(0,80))))
pt = st_point(c(0,90))
x = st_sfc(pole, pt, crs = 4326)
st_geod_covers(x[c(1,1,1)], x[c(2,2,2,2)])
pole = st_polygon(list(rbind(c(0,80), c(120,80), c(240,80), c(0,80))))
pt = st_point(c(30,70))
x = st_sfc(pole, pt, crs = 4326)
st_geod_distance(x, x)
Provide the external dependencies versions of the libraries linked to sf
Description
Provide the external dependencies versions of the libraries linked to sf
Usage
lwgeom_extSoftVersion()
Make an invalid geometry valid
Description
Make an invalid geometry valid
Usage
lwgeom_make_valid(x)
Arguments
x |
object of class |
compute perimeter from polygons or other geometries
Description
compute perimeter from polygons or other geometries
Usage
st_perimeter_lwgeom(x)
st_perimeter(x)
st_perimeter_2d(x)
Arguments
x |
object of class |
Value
numerical vector with perimeter for each feature (geometry), with unit of measure when possible
create sfc object from tiny well-known binary (twkb)
Description
create sfc object from tiny well-known binary (twkb)
Usage
## S3 method for class 'TWKB'
st_as_sfc(x, ...)
Arguments
x |
list with raw vectors, of class |
... |
ignored |
See Also
https://github.com/TWKB/Specification/blob/master/twkb.md
Examples
l = structure(list(as.raw(c(0x02, 0x00, 0x02, 0x02, 0x02, 0x08, 0x08))), class = "TWKB")
library(sf) # load generic
st_as_sfc(l)
Return Well-known Text representation of simple feature geometry
Description
Return Well-known Text representation of simple feature geometry or coordinate reference system
Usage
st_astext(x, digits = options("digits"), ..., EWKT = FALSE)
st_asewkt(x, digits = options("digits"))
Arguments
x |
object of class |
digits |
integer; number of decimal digits to print |
... |
ignored |
EWKT |
logical; use PostGIS Enhanced WKT (includes srid) |
Details
The returned WKT representation of simple feature geometry conforms to the
simple features access specification and extensions (if EWKT = TRUE),
known as EWKT, supported by
PostGIS and other simple features implementations for addition of SRID to a WKT string.
st_asewkt() returns the Well-Known Text (WKT) representation of
the geometry with SRID meta data.
Examples
library(sf)
pt <- st_sfc(st_point(c(1.0002,2.3030303)), crs = 4326)
st_astext(pt, 3)
st_asewkt(pt, 3)
Force a POLYGON or MULTIPOLYGON to be clockwise
Description
Check if a POLYGON or MULTIPOLYGON is clockwise, and if not make it so. According to the 'Right-hand-rule', outer rings should be clockwise, and inner holes should be counter-clockwise
Usage
st_force_polygon_cw(x)
Arguments
x |
object with polygon geometries |
Value
object of the same class as x
Examples
library(sf)
polys <- st_sf(cw = c(FALSE, TRUE),
st_as_sfc(c('POLYGON ((0 0, 1 0, 1 1, 0 0))',
'POLYGON ((1 1, 2 2, 2 1, 1 1))')))
st_force_polygon_cw(polys)
st_force_polygon_cw(st_geometry(polys))
st_force_polygon_cw(st_geometry(polys)[[1]])
compute azimuth between sequence of points
Description
compute azimuth between sequence of points
Usage
st_geod_azimuth(x)
Arguments
x |
object of class |
Examples
library(sf)
p = st_sfc(st_point(c(7,52)), st_point(c(8,53)), crs = 4326)
st_geod_azimuth(p)
compute geohash from (average) coordinates
Description
compute geohash from (average) coordinates
Usage
st_geohash(x, precision = 0)
Arguments
x |
object of class |
precision |
integer; precision (length) of geohash returned. From the liblwgeom source: “where the precision is non-positive, a precision based on the bounds of the feature. Big features have loose precision. Small features have tight precision.” |
Details
see http://geohash.org/ or https://en.wikipedia.org/wiki/Geohash.
Value
character vector with geohashes
Examples
library(sf)
lwgeom::st_geohash(st_sfc(st_point(c(1.5,3.5)), st_point(c(0,90))), 2)
lwgeom::st_geohash(st_sfc(st_point(c(1.5,3.5)), st_point(c(0,90))), 10)
Check if a POLYGON or MULTIPOLYGON is clockwise
Description
Check if a POLYGON or MULTIPOLYGON is clockwise. According to the 'Right-hand-rule', outer rings should be clockwise, and inner holes should be counter-clockwise
Usage
st_is_polygon_cw(x)
Arguments
x |
object with polygon geometries |
Value
logical with length the same number of features in 'x'
Examples
library(sf)
polys <- st_sf(cw = c(FALSE, TRUE),
st_as_sfc(c('POLYGON ((0 0, 1 0, 1 1, 0 0))',
'POLYGON ((1 1, 2 2, 2 1, 1 1))')))
st_is_polygon_cw(polys)
st_is_polygon_cw(st_geometry(polys))
st_is_polygon_cw(st_geometry(polys)[[1]])
get substring from linestring
Description
get substring from linestring
Usage
st_linesubstring(x, from, to, tolerance, ...)
Arguments
x |
object of class |
from |
relative distance from origin (in [0,1]) |
to |
relative distance from origin (in [0,1]) |
tolerance |
tolerance parameter, when to snap to line node node |
... |
ignored |
Value
object of class sfc
Examples
library(sf)
lines = st_sfc(st_linestring(rbind(c(0,0), c(1,2), c(2,0))), crs = 4326)
spl = st_linesubstring(lines, 0.2, 0.8) # should warn
plot(st_geometry(lines), col = 'red', lwd = 3)
plot(spl, col = 'black', lwd = 3, add = TRUE)
st_linesubstring(lines, 0.49999, 0.8) # three points
st_linesubstring(lines, 0.49999, 0.8, 0.001) # two points: snap start to second node
Snap geometries to a grid
Description
Snap geometries to a grid
Usage
st_snap_to_grid(x, size, origin)
Arguments
x |
object with geometries to be snapped |
size |
numeric or (length) units object; grid cell size in x-, y- (and possibly z- and m-) directions |
origin |
numeric; origin of the grid |
Value
object of the same class as x
Examples
# obtain data
library(sf)
x = st_read(system.file("gpkg/nc.gpkg", package="sf"), quiet = TRUE)[1, ] %>%
st_geometry %>%
st_transform(3395)
# snap to a grid of 5000 m
err = try(y <- st_snap_to_grid(x, 5000))
# plot data for visual comparison
if (!inherits(err, "try-error")) {
opar = par(mfrow = c(1, 2))
plot(x, main = "orginal data")
plot(y, main = "snapped to 5000 m")
par(opar)
}
Return a collection of geometries resulting by splitting a geometry
Description
Return a collection of geometries resulting by splitting a geometry
Usage
st_split(x, y)
Arguments
x |
object with geometries to be splitted |
y |
object split with (blade); if |
Value
object of the same class as x
Examples
library(sf)
l = st_as_sfc('MULTILINESTRING((10 10, 190 190), (15 15, 30 30, 100 90))')
pt = st_sfc(st_point(c(30,30)))
st_split(l, pt)
Return the start and end points from lines
Description
Return the start and end points from lines
Usage
st_startpoint(x)
st_endpoint(x)
Arguments
x |
line of class |
Details
see https://postgis.net/docs/ST_StartPoint.html and https://postgis.net/docs/ST_EndPoint.html.
Value
sf object representing start and end points
Examples
library(sf)
m = matrix(c(0, 1, 2, 0, 1, 4), ncol = 2)
l = st_sfc(st_linestring(m))
lwgeom::st_startpoint(l)
lwgeom::st_endpoint(l)
l2 = st_sfc(st_linestring(m), st_linestring(m[3:1, ]))
lwgeom::st_startpoint(l2)
lwgeom::st_endpoint(l2)
Return a collection of geometries resulting by subdividing a geometry
Description
Return a collection of geometries resulting by subdividing a geometry
Usage
st_subdivide(x, max_vertices)
Arguments
x |
object with geometries to be subdivided |
max_vertices |
integer; maximum size of the subgeometries (at least 8) |
Value
object of the same class as x
Examples
library(sf)
demo(nc, ask = FALSE, echo = FALSE)
x = st_subdivide(nc, 10)
plot(x[1])
Transform or convert coordinates of simple features directly with Proj.4 (bypassing GDAL)
Description
Transform or convert coordinates of simple features directly with Proj.4 (bypassing GDAL)
Usage
st_transform_proj(x, crs, ...)
## S3 method for class 'sfc'
st_transform_proj(x, crs, ...)
## S3 method for class 'sf'
st_transform_proj(x, crs, ...)
## S3 method for class 'sfg'
st_transform_proj(x, crs, ...)
Arguments
x |
object of class sf, sfc or sfg |
crs |
character; target CRS, or, in case of a length 2 character vector, source and target CRS |
... |
ignored |
Details
Transforms coordinates of object to new projection, using PROJ directly rather than the GDAL API used by st_transform.
If crs is a single CRS, it forms the target CRS, and in that case the source CRS is obtained as st_crs(x). Since this presumes that the source CRS is accepted by GDAL (which is not always the case), a second option is to specify the source and target CRS as two proj4strings in argument crs. In the latter case, st_crs(x) is ignored and may well be NA.
The st_transform_proj method for sfg objects assumes that the CRS of the object is available as an attribute of that name.
Examples
library(sf)
p1 = st_point(c(7,52))
p2 = st_point(c(-30,20))
sfc = st_sfc(p1, p2, crs = 4326)
sfc
st_transform_proj(sfc, "+proj=wintri")
library(sf)
nc = st_read(system.file("shape/nc.shp", package="sf"))
st_transform_proj(nc[1,], "+proj=wintri +over")
st_transform_proj(structure(p1, proj4string = "+init=epsg:4326"), "+init=epsg:3857")
Splits input geometries by a vertical line and moves components falling on one side of that line by a fixed amount
Description
Splits input geometries by a vertical line and moves components falling on one side of that line by a fixed amount
Usage
st_wrap_x(x, wrap, move)
Arguments
x |
object with geometries to be split |
wrap |
x value of split line |
move |
amount by which geometries falling to the left of the line should be translated to the right |
Value
object of the same class as x
Examples
library(sf)
demo(nc, ask = FALSE, echo = FALSE)
x = st_wrap_x(nc, -78, 10)
plot(x[1])