Percentage of Like Adjacencies (Aggregation metric)
Arguments
- landscape
A categorical raster object: SpatRaster; Raster* Layer, Stack, Brick; stars or a list of SpatRasters.
Details
$$PLADJ = (\frac{g_{ij}} {\sum \limits_{k = 1}^{m} g_{ik}}) * 100$$
where \(g_{ii}\) is the number of adjacencies between cells of class i
and \(g_{ik}\) is the number of adjacencies between cells of class i and k.
PLADJ is an 'Aggregation metric'. It calculates the frequency how often patches of
different classes i (focal class) and k are next to each other, and following is a
measure of class aggregation. The adjacencies are counted using the double-count method.
Behaviour
Equals PLADJ = 0 if class i is maximal disaggregated,
i.e. every cell is a different patch. Equals PLADJ = 100 when the only one patch
is present.
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.
Examples
landscape <- terra::rast(landscapemetrics::landscape)
lsm_c_pladj(landscape)
#> # A tibble: 3 × 6
#> layer level class id metric value
#> <int> <chr> <int> <int> <chr> <dbl>
#> 1 1 class 1 NA pladj 73.6
#> 2 1 class 2 NA pladj 74.4
#> 3 1 class 3 NA pladj 81.0
