CONTIG_SD (class level)

Standard deviation of Contiguity index (Shape metric)

Usage

lsm_c_contig_sd(landscape, directions = 8)

Arguments

landscape: 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).

Value

tibble

Details

$$CONTIG_{SD} = sd(CONTIG[patch_{ij}])$$

where $CONTIG[patch_{ij}]$ is the contiguity of each patch.

CONTIG_SD is a 'Shape metric'. It summarises each class as the mean of each patch belonging to class i. CONTIG_SD asses the spatial connectedness (contiguity) of cells in patches. The metric coerces patch values to a value of 1 and the background to NA. A nine cell focal filter matrix:

filter_matrix <- matrix(c(1, 2, 1,
                          2, 1, 2,
                          1, 2, 1), 3, 3, byrow = T)

... is then used to weight orthogonally contiguous pixels more heavily than diagonally contiguous pixels. Therefore, larger and more connections between patch cells in the rookie case result in larger contiguity index values.

Units

None

Range

CONTIG_CV >= 0

Behaviour

CONTIG_SD = 0 if the contiguity index is identical for all patches. Increases, without limit, as the variation of CONTIG 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

LaGro, J. 1991. Assessing patch shape in landscape mosaics. Photogrammetric Engineering and Remote Sensing, 57(3), 285-293

Examples

landscape <- terra::rast(landscapemetrics::landscape)
lsm_c_contig_sd(landscape)
#> # A tibble: 3 × 6
#>   layer level class    id metric    value
#>   <int> <chr> <int> <int> <chr>     <dbl>
#> 1     1 class     1    NA contig_sd 0.321
#> 2     1 class     2    NA contig_sd 0.330
#> 3     1 class     3    NA contig_sd 0.151