Raster Cell Neighbourhoods

Usage

tj_cell_neighbours(
  i,
  nr,
  nc,
  ...,
  type = "square",
  range = 1,
  scale_to_8 = FALSE
)

Arguments

i: focal cell
nr: number of rows in the xy-grid
nc: number of columns in the xy-grid
...: ignored
type: "square" (default), "circle", "sqexp"
range: Range of neighbourhood, default is 1 for 1-step-neighbourhoods
scale_to_8: normalise the kernel to 8?

Value

A vector of indices. If `type='sqexp'`, will return the weights in the attribute 'weight'.

Details

The default is `type='square'` and `range=1`, which is 8 adjacent pixels. Increasing `range=2` includes the neighbours' neighbours (24 pixels).

To return neighbourhood with corners removed, use `type='circle'` which drops the pixels from square-neighbourhood with distance larger than `range`.

To weight the further away neighbours, use `type='sqexp'`. It is similar to circle, but with weight decreasing exponentially in squared distance, scaled to be 1 for distance 1.

Non-toroidal neighborhood, so at edges there will be less neighbours.

Will assume cell-numbering cell = col + (row-1) * ncol.