# lsm_c_pafrac: PAFRAC (class level) In r-spatialecology/landscapemetrics: Landscape Metrics for Categorical Map Patterns

## Description

Perimeter-Area Fractal Dimension (Shape metric)

## Usage

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 lsm_c_pafrac(landscape, directions, verbose) ## S3 method for class 'RasterLayer' lsm_c_pafrac(landscape, directions = 8, verbose = TRUE) ## S3 method for class 'RasterStack' lsm_c_pafrac(landscape, directions = 8, verbose = TRUE) ## S3 method for class 'RasterBrick' lsm_c_pafrac(landscape, directions = 8, verbose = TRUE) ## S3 method for class 'stars' lsm_c_pafrac(landscape, directions = 8, verbose = TRUE) ## S3 method for class 'list' lsm_c_pafrac(landscape, directions = 8, verbose = TRUE) 

## Arguments

 landscape Raster* Layer, Stack, Brick or a list of rasterLayers. directions The number of directions in which patches should be connected: 4 (rook's case) or 8 (queen's case). verbose Print warning message if not sufficient patches are present

## Details

PAFRAC = \frac{2}{β}

where β is the slope of the regression of the area against the perimeter (logarithm) n_{i}∑ \limits_{j = 1}^{n} \ln a_{ij} = a + β n_{i}∑ \limits_{j = 1}^{n} \ln p_{ij}

PAFRAC is a 'Shape metric'. It describes the patch complexity of class i while being scale independent. This means that increasing the patch size while not changing the patch form will not change the metric. However, it is only meaningful if the relationship between the area and perimeter is linear on a logarithmic scale. Furthermore, if there are less than 10 patches in class i, the metric returns NA because of the small-sample issue.

None

1 <= PAFRAC <= 2

#### Behaviour

Approaches PAFRAC = 1 for patches with simple shapes and approaches PAFRAC = 2 for irregular shapes

tibble

## References

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

Burrough, P. A. 1986. Principles of Geographical Information Systems for Land Resources Assessment. Monographs on Soil and Resources Survey No. 12. Clarendon Press, Oxford

lsm_p_area, lsm_p_perim,
lsm_l_pafrac
 1 lsm_c_pafrac(landscape)