landscapeR (version 1.3.1)

makeClass: Create a class of patches.

Description

Create a class of patches.

Usage

makeClass(
  context,
  npatch,
  size,
  pts = NULL,
  bgr = 0,
  edge = FALSE,
  rast = TRUE,
  val = 1
)

Value

A SpatRaster object, or a vector of cell numbers if rast=FALSE.

Arguments

context

SpatRaster object, a raster of an empty landscape or a mask, indicating where the patch cannot be generated (see bgr argument).

npatch

number of patches per class

size

integer. The size of patches, as number of raster cells. A single integer can be provided, in which case all patches will have that size.

pts

integer or matrix. The seed point location around which the patches are built (random points are given by default). It can be an integer, as indexes of the cells in the raster, or a two columns matrix indicating x and y coordinates.

bgr

integer. A single value of background cells, where a patch can be generated (default is zero). Cells/classes which cannot be changed must have a different value.

edge

logical. Should the vector of edge cells of the patch be returned?

rast

logical. If TRUE returns a SpatRaster object, otherwise a vector of cell numbers where the patch occurs

val

integer. The value to be assigned to patch cells, when rast=TRUE

Details

The patches created can be contiguous, therefore resembling a single patch with size equal to the sum of contiguous cells. The patches are created starting from the seed points (if provided) and iteratively sampling randomly neighbouring cells at the edge of the patch, according to von Neumann neighbourhood (four cells, aka Rook case). There is a tolerance of +/- 3 cells from the patch size declared in size argument.

Examples

library(terra)
mtx = matrix(0, 33, 33)
r = rast(mtx)
ext(r) = c(0, 10, 0, 10)
num = 5
size = 15
rr = makeClass(r, num, size)
plot(rr)

## Create a class of three patches of given size at three corners of the spatial context
size = c(10, 50, 200)
pts = c(1, 33, 1089)
rr = makeClass(r, 3, size, pts)
plot(rr)