GYRATE (patch level)

Radius of Gyration (Area and edge metric)

Usage

lsm_p_gyrate(landscape, directions = 8, cell_center = FALSE)

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).

cell_center

If true, the coordinates of the centroid are forced to be a cell center within the patch.

Value

tibble

Details

$$GYRATE = \sum \limits_{r = 1}^{z} \frac{h_{ijr}} {z}$$ where \(h_{ijr}\) is the distance from each cell to the centroid of the patch and \(z\) is the number of cells.

GYRATE is an 'Area and edge metric'. The distance from each cell to the patch centroid is based on cell center to centroid distances. The metric characterises both the patch area and compactness.

If cell_center = TRUE some patches might have several possible cell-center centroids. In this case, the gyrate index is based on the mean distance of all cells to all possible cell-center centroids.

Units

Meters

Range

GYRATE >= 0

Behaviour

Approaches GYRATE = 0 if patch is a single cell. Increases, without limit, when 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

Keitt, T. H., Urban, D. L., & Milne, B. T. 1997. Detecting critical scales in fragmented landscapes. Conservation ecology, 1(1).

See also

lsm_c_gyrate_mn, lsm_c_gyrate_sd, lsm_c_gyrate_cv,
lsm_l_gyrate_mn, lsm_l_gyrate_sd, lsm_l_gyrate_cv

Examples

landscape <- terra::rast(landscapemetrics::landscape)
lsm_p_gyrate(landscape)
#> # A tibble: 28 × 6
#>    layer level class    id metric value
#>    <int> <chr> <int> <int> <chr>  <dbl>
#>  1     1 patch     1     1 gyrate 0    
#>  2     1 patch     1     2 gyrate 1.00 
#>  3     1 patch     1     3 gyrate 4.09 
#>  4     1 patch     1     4 gyrate 0    
#>  5     1 patch     1     5 gyrate 0    
#>  6     1 patch     1     6 gyrate 4.01 
#>  7     1 patch     1     7 gyrate 1.75 
#>  8     1 patch     1     8 gyrate 0.863
#>  9     1 patch     1     9 gyrate 0.848
#> 10     1 patch     2    10 gyrate 2.53 
#> # ℹ 18 more rows