A categorical raster object: SpatRaster; Raster* Layer, Stack, Brick; stars or a list of SpatRasters
directions
The number of directions in which patches should be
connected: 4 (rook's case) or 8 (queen's case).
Details
$$PARA = \frac{p_{ij}} {a_{ij}}$$
where \(p_{ij}\) is the perimeter in meters and \(a_{ij}\) is the
area in square meters.
PARA is a 'Shape metric'. It describes the patch complexity in a
straightforward way. However, because it is not standarised to a certain
shape (e.g. a square), it is not scale independent, meaning that increasing
the patch size while not changing the patch form will change the ratio.
Units
None
Range
PARA > 0
Behaviour
Increases, without limit, as the shape complexity
increases.
References
McGarigal K., SA Cushman, and E Ene. 2023. FRAGSTATS v4: Spatial Pattern Analysis
Program for Categorical Maps. Computer software program produced by the authors;
available at the following web site: https://www.fragstats.org