SHAPE (patch level)

Shape index (Shape metric)

Usage

lsm_p_shape(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

$$SHAPE = \frac{0.25 * p_{ij}} {\sqrt a_{ij}}$$ where \(p_{ij}\) is the perimeter (m) and \(a_{ij}\) is the area (m2).

SHAPE is a 'Shape metric'. It describes the ratio between the actual perimeter of the patch and the square root of patch area and thus adjusting for a square standard. Thus, it is a simple measure of shape complexity.

Because the metric is based on distances or areas please make sure your data is valid using check_landscape.

Units

None

Range

SHAPE >= 1

Behaviour

Equals SHAPE = 1 for a squared patch and increases, without limit, as the patch shape becomes more complex.

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.

See also

lsm_p_perim, lsm_p_area,
lsm_c_shape_mn, lsm_c_shape_sd, lsm_c_shape_cv,
lsm_l_shape_mn, lsm_l_shape_sd, lsm_l_shape_cv

Examples

landscape <- terra::rast(landscapemetrics::landscape)
lsm_p_shape(landscape)
#> # A tibble: 28 × 6
#>    layer level class    id metric value
#>    <int> <chr> <int> <int> <chr>  <dbl>
#>  1     1 patch     1     1 shape   1   
#>  2     1 patch     1     2 shape   1.34
#>  3     1 patch     1     3 shape   1.77
#>  4     1 patch     1     4 shape   1   
#>  5     1 patch     1     5 shape   1   
#>  6     1 patch     1     6 shape   1.90
#>  7     1 patch     1     7 shape   1.38
#>  8     1 patch     1     8 shape   1.44
#>  9     1 patch     1     9 shape   1.12
#> 10     1 patch     2    10 shape   1.63
#> # ℹ 18 more rows