st_crop: crop a stars object

In stars: Spatiotemporal Arrays, Raster and Vector Data Cubes

crop a stars object

Description

crop a stars object

Usage

## S3 method for class 'mdim'
st_crop(x, y, ...)

## S3 method for class 'stars_proxy'
st_crop(
  x,
  y,
  ...,
  crop = TRUE,
  epsilon = sqrt(.Machine$double.eps),
  collect = TRUE
)

## S3 method for class 'stars'
st_crop(
  x,
  y,
  ...,
  crop = TRUE,
  epsilon = sqrt(.Machine$double.eps),
  as_points = all(st_dimension(y) == 2, na.rm = TRUE),
  normalize = FALSE
)

Arguments

x	object of class stars
y	object of class sf, sfc or bbox; see Details below.
...	ignored
crop	logical; if TRUE, the spatial extent of the returned object is cropped to still cover obj, if FALSE, the extent remains the same but cells outside y are given NA values.
epsilon	numeric; factor to shrink the bounding box of y towards its center before cropping.
collect	logical; if TRUE, repeat cropping on stars object, i.e. after data has been read
as_points	logical; only relevant if y is of class sf or sfc: if FALSE, treat x as a set of points, else as a set of small polygons. Default: TRUE if y is two-dimensional, else FALSE; see Details
normalize	logical; if TRUE then pass the cropped object to st_normalize before returning. This typically changes the 'offset' field and resets the 'from' field to 1, and changes the bounding box of the returned object accordingly.

Details

for raster x, st_crop selects cells that intersect with y. For intersection, are raster cells interpreted as points or as small polygons? If y is of class stars, x raster cells are interpreted as points; if y is of class bbox, x cells are interpreted as cells (small polygons). Otherwise, if as_points is not given, cells are interpreted as points if y has a two-dimensional geometry.

Examples

l7 = read_stars(system.file("tif/L7_ETMs.tif", package = "stars"))
d = st_dimensions(l7)

# area around cells 3:10 (x) and 4:11 (y):
offset = c(d[["x"]]$offset, d[["y"]]$offset)
res = c(d[["x"]]$delta, d[["y"]]$delta)
bb = st_bbox(c(xmin = offset[1] + 2 * res[1],
	ymin = offset[2] + 11 * res[2],
	xmax = offset[1] + 10 * res[1],
	ymax = offset[2] +  3 * res[2]), crs = st_crs(l7))
l7[bb]
# equivalent:
st_crop(l7, bb)

plot(l7[,1:13,1:13,1], reset = FALSE)
image(l7[bb,,,1], add = TRUE, col = sf.colors())
plot(st_as_sfc(bb), add = TRUE, border = 'green', lwd = 2)

# slightly smaller bbox:
bb = st_bbox(c(xmin = offset[1] + 2.1 * res[1],
	ymin = offset[2] + 10.9 * res[2],
	xmax = offset[1] +  9.9 * res[1],
	ymax = offset[2] +  3.1 * res[2]), crs = st_crs(l7))
l7[bb]

plot(l7[,1:13,1:13,1], reset = FALSE)
image(l7[bb,,,1], add = TRUE, col = sf.colors())
plot(st_as_sfc(bb), add = TRUE, border = 'green', lwd = 2)

# slightly larger bbox:
bb = st_bbox(c(xmin = offset[1] + 1.9 * res[1],
	ymin = offset[2] + 11.1 * res[2],
	xmax = offset[1] + 10.1 * res[1],
	ymax = offset[2] +  2.9 * res[2]), crs = st_crs(l7))
l7[bb]

plot(l7[,1:13,1:13,1], reset = FALSE)
image(l7[bb,,,1], add = TRUE, col = sf.colors())
plot(st_as_sfc(bb), add = TRUE, border = 'green', lwd = 2)

# half a cell size larger bbox:
bb = st_bbox(c(xmin = offset[1] + 1.49 * res[1],
	ymin = offset[2] + 11.51 * res[2],
	xmax = offset[1] + 10.51 * res[1],
	ymax = offset[2] +  2.49 * res[2]), crs = st_crs(l7))
l7[bb]

plot(l7[,1:13,1:13,1], reset = FALSE)
image(l7[bb,,,1], add = TRUE, col = sf.colors())
plot(st_as_sfc(bb), add = TRUE, border = 'green', lwd = 2)

stars documentation built on April 4, 2025, 4:34 a.m.