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SHAPE_MN (class level)

Source: R/lsm_c_shape_mn.R
lsm_c_shape_mn.Rd

Mean shape index (Shape metric)

Usage

lsm_c_shape_mn(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

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

SHAPE_MN is a 'Shape metric'. Each class is summarised as the mean of each patch belonging to class i. SHAPE describes the ratio between the actual perimeter of the patch and the square root of patch area.

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

Units

None

Range

SHAPE_SD >= 1

Behaviour

Equals SHAPE_MN = 1 if all patches are squares. Increases, without limit, as the shapes of patches become 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_shape, mean,
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_c_shape_mn(landscape)
#> # A tibble: 3 × 6
#>   layer level class    id metric   value
#>   <int> <chr> <int> <int> <chr>    <dbl>
#> 1     1 class     1    NA shape_mn  1.33
#> 2     1 class     2    NA shape_mn  1.22
#> 3     1 class     3    NA shape_mn  1.75