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Modify the geometry of a simple feature or bounding box object

Source: R/st_misc.R
st_misc.Rd

Support sf, sfc, and bbox and objects as inputs.

  • Get the center point for a sf object

  • Get a circumscribed circle or inscribed circle in a sf object

  • Get a donut for a sf object (may not work if inscribed = TRUE)

st_inscribed_square wraps sf::st_inscribed_circle() but limits the circle to 1 segment per quadrant (nQuadSegs = 1) and then rotates the resulting geometry 45 degrees to provide a (mostly) inscribed square. A different rotation value can be provided to change the orientation of the shape, e.g. rotate = -45 to return a diamond shape. st_square() wraps st_bbox_ext() with asp = 1.

Usage

st_center(x, class = "list", ext = TRUE, ...)

st_circle(
  x,
  scale = 1,
  inscribed = TRUE,
  dTolerance = 0.01,
  by_feature = FALSE,
  use_hull = FALSE,
  use_lwgeom = FALSE
)

st_circumscribed_circle(x, scale = 1, dTolerance = 0, by_feature = FALSE)

st_donut(x, width = 0.4, scale = 1, inscribed = FALSE, by_feature = TRUE, ...)

Arguments

x

A sf, sfc, or bbox object

class

Class to return for st_center(): "sfc", "sf", "geometry" (original input geometry), "x" (original input object), "crs" (original input crs), or "list" (including all other class types).

ext

If TRUE, st_center returns a list with the centroid as a sfc object, as an sf object (with lon and lat values), the original geometry (x), and the original crs. objects; defaults TRUE. If FALSE, return an sf object.

...

Additional parameters passed to sf::st_centroid() by st_center() or st_circle() by st_donut().

scale

For st_donut(), scale to apply to donut using st_circle(). Defaults to 1 which keeps the donut as the same size as the input object.

inscribed

If TRUE, make circle, square, or donut inscribed within x, if FALSE, make it circumscribed.

dTolerance

numeric; tolerance parameter, specified for all or for each feature geometry. If you run st_simplify, the input data is specified with long-lat coordinates and sf_use_s2() returns TRUE, then the value of dTolerance must be specified in meters.

by_feature

For st_donut(), if TRUE the input object x is unioned before converting into a donut geometry. If FALSE, each feature in the input data remains a separate feature in the output.

use_hull

For st_circle(), if TRUE use the geometry from sf::st_convex_hull() (to address issues with MULTIPOLYGON objects).

use_lwgeom

If TRUE, by_feature = TRUE and inscribed = FALSE, use lwgeom::st_minimum_bounding_circle().

width

Donut width as proportion of outer size.

See also

Examples

nc <- sf::read_sf(system.file("shape/nc.shp", package = "sf"))
nc <- sf::st_transform(nc, crs = 3857)

plot(nc, max.plot = 1)


plot(st_circumscribed_circle(nc, by_feature = FALSE), max.plot = 1)
plot(st_circle(nc, by_feature = FALSE), max.plot = 1, add = TRUE)


plot(st_donut(nc[1:10,], by_feature = TRUE), max.plot = 1)