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Coefficient of variation shape index (Shape metric)

Usage

lsm_l_shape_cv(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

$$SHAPE_{CV} = cv(SHAPE[patch_{ij}])$$ where \(SHAPE[patch_{ij}]\) is the shape index of each patch.

SHAPE_CV is a 'Shape metric'. The landscape is summarised as the Coefficient of variation of all patches in the landscape. SHAPE describes the ratio between the actual perimeter of the patch and the square root of patch area.

Units

None

Range

SHAPE_CV >= 0

Behaviour

Equals SHAPE_CV = 0 if all patches have an identical shape index. Increases, without limit, as the variation of the shape index 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

Patton, D. R. 1975. A diversity index for quantifying habitat "edge". Wildl. Soc.Bull. 3:171-173.

Examples

landscape <- terra::rast(landscapemetrics::landscape)
lsm_l_shape_cv(landscape)
#> # A tibble: 1 × 6
#>   layer level     class    id metric   value
#>   <int> <chr>     <int> <int> <chr>    <dbl>
#> 1     1 landscape    NA    NA shape_cv  27.3