vm_p_circle.RdRelated Circumscribing Circle (Shape metric)
vm_p_circle(landscape, class_col = NULL, patch_col = NULL)*sf* MULTIPOLYGON or POLYGON feature
Name of the class column of the input landscape
the name of the id column of the input landscape
the function returns tibble with the calculated values in column "value", this function returns also some important information such as level, class, patch id and metric name.
$$CIRCLE = 1 - (\frac{a_{ij}} {a_{ij}^{circle}})$$ where \(a_{ij}\) is the area in square meters and \(a_{ij}^{circle}\) the area of the smallest circumscribing circle.
CIRCLE is a 'Shape metric'. The metric is the ratio between the patch area and the smallest circumscribing circle of the patch. The diameter of the smallest circumscribing circle is the 'diameter' of the patch connecting the opposing corner points of the polygon that are the furthest away from each other. The metric characterises the compactness of the patch and is comparable among patches with different area.
McGarigal, K., SA Cushman, and E Ene. 2012. FRAGSTATS v4: Spatial Pattern Analysis Program for Categorical and Continuous Maps. Computer software program produced by the authors at the University of Massachusetts, Amherst. Available at the following web site: http://www.umass.edu/landeco/research/fragstats/fragstats.html
Baker, W. L., and Y. Cai. 1992. The r.le programs for multiscale analysis of landscape structure using the GRASS geographical information system. Landscape Ecology 7: 291-302.
vm_p_circle(vector_patches, "class", "patch")
#> # A tibble: 40 × 5
#> level class id metric value
#> <chr> <chr> <chr> <chr> <dbl>
#> 1 patch 1 11 circle 0.659
#> 2 patch 1 12 circle 0.395
#> 3 patch 1 13 circle 0.583
#> 4 patch 1 14 circle 0.608
#> 5 patch 1 15 circle 0.363
#> 6 patch 1 16 circle 0.363
#> 7 patch 1 17 circle 0.363
#> 8 patch 1 18 circle 0.412
#> 9 patch 1 19 circle 0.363
#> 10 patch 1 20 circle 0.363
#> # ℹ 30 more rows