Return common bounding of multiple spatial objects or aligned bounding of single spatial object

Return common bounding of multiple spatial objects or aligned bounding of single spatial object

st_bbox_common(...)

st_bbox_list(l)

st_bbox_aligned(obj, alignment)

Arguments

...

objects that can be coerced to bounding boxes with bb or with st_bbox

l

list of objects that can be coerced to bounding boxes with bb or with st_bbox

obj

any object that can be coerced to a bounding box with st_bbox

alignment

single positive numeric value, corresponding to the units of the CRS, which the input object has.

Value

object of the class bbox equal to the return of st_bbox representing in the case of

• st_bbox_common() or st_bbox_list() the common bounding of several (listed) input objects

• st_bbox_aligned() the aligned bounding of a single input object. Returned values xmin, ymin, xmax and ymax match \(k\) \(\cdot\) alignment-argument, where \(k\) is an integer. The input object is positioned within these four coordinates.

Examples

library(sf)
library(stars)
#> Loading required package: abind
library(terra)
#> terra 1.8.93

# get /create spatial objects of different classes and extent:
sf <- st_read(system.file("gpkg/nc.gpkg", package = "sf"), quiet = TRUE)
logo <- rast(system.file("ex/logo.tif", package = "terra"))
rast <- rast(
  val    = as.vector(logo$red),
  nrows  = nrow(logo),
  ncols  = ncol(logo),
  extent = c(-77, -75, 33, 35),
  crs    = st_crs(sf)$wkt
  )
stars <- st_as_stars(rast) %>% st_set_bbox(., st_bbox(.) + rep(2, 4)) %>% st_flip()

# common extent / bbox:
(bbox_common <- st_bbox_common(sf, rast, stars))
#>      xmin      ymin      xmax      ymax 
#> -84.32385  33.00000 -73.00000  37.00000 

# map objects within their common extent:
library(tmap)
tm_shape(stars, bbox = bbox_common) +
tm_raster(
  col.scale = tm_scale_continuous(values = "brewer.spectral"),
  col.legend = tm_legend(
    title    = "stars",
    frame    = FALSE,
    reverse  = TRUE,
    height   = 10,
    position = tm_pos_in("left", "bottom")
  )) +
  tm_shape(rast) +
  tm_raster(
    col.scale = tm_scale_continuous(values = "viridis"),
    col.legend = tm_legend(
      title    = "SpatRaster",
      frame    = FALSE,
      reverse  = TRUE,
      height   = 10,
      position = tm_pos_in("left", "bottom")
    )) +
  tm_shape(sf) + tm_borders(col = "magenta") +
  tm_layout(legend.stack = "horizontal")


# list of sf objects
l <- lapply(1:nrow(sf), function(x) sf[x, ])

# bbox of all listed sf objects
st_bbox_list(l)
#>      xmin      ymin      xmax      ymax 
#> -84.32385  33.88199 -75.45698  36.58965 

# the bbox of the original geometry set (sf) and the bbox of its listed objects are identical:
all.equal(st_bbox_list(l), st_bbox(sf))
#> [1] TRUE

# get pretty / aligned bbox of an object
(bb_aligned <- st_bbox_aligned(sf, alignment = 2.5))
#>  xmin  ymin  xmax  ymax 
#> -85.0  32.5 -75.0  37.5 

# dividing the aligned bbox by the alignment value results in integer values
bb_aligned / 2.5
#> xmin ymin xmax ymax 
#>  -34   13  -30   15 

# plot used object within extent of aligned bbox
plot(st_geometry(sf), extent = bb_aligned, col = "gray")

# add to plot grid matching the alignment (= cellsize)
grid_aligned <- st_make_grid(bb_aligned, cellsize = 2.5)
plot(grid_aligned, border = "red", lwd = 2, add = TRUE)