add_compactness_constraint: Add constraint to limit compactness

In restoptr: Ecological Restoration Planning

Add constraint to limit compactness

Description

Add constraint to a restoration problem (restopt_problem()) object to specify the compactness of a solution.

Usage

add_compactness_constraint(problem, max_diameter, unit = "m")

Arguments

problem	restopt_problem() Restoration problem object.
max_diameter	numeric Maximum diameter value.
unit	unit object or a character that can be coerced to an area unit (see unit package), or "cells" for cell width of aggregated habitat raster. Corresponds to the unit of the maximum diameter. If the input habitat raster does not use a projected coordinate system, only "cells" is available.

Details

The compactness constraint is defined according to the diameter of the smallest enclosing circle which contains the center of selected planning units for restoration (see https://w.wiki/4vfg). The unit of the diameter corresponds either to a unit available in the unit package, or to planning unit width ("cells"). Note that, as the computation occurs on aggregated cells, if max_diameter is used with a different unit than "cells", it will be rounded to the closest corresponding number of cells. For example, a diameter of 4 cells means that no more than 4 cells can be found in line in the solution. In practice, this constraint is useful to ensure the feasibility of a restoration project, and to integrate economies of scale. Compact restoration areas are usually associated with lower costs and easier management, because it ensures that restoration sites are not too far away from each other (e.g. lower travel costs between sites, less areas to monitor, etc.).

Value

An updated restoration problem (restopt_problem()) object.

See Also

Other constraints: add_available_areas_constraint(), add_components_constraint(), add_connected_constraint(), add_locked_out_constraint(), add_min_iic_constraint(), add_min_mesh_constraint(), add_nb_patches_constraint(), add_no_new_patch_constraint(), add_restorable_constraint()

Examples

## Not run: 
# load data
habitat_data <- rast(
  system.file("extdata", "habitat_hi_res.tif", package = "restoptr")
)

# create problem
p <- restopt_problem(
    existing_habitat = habitat_data,
    aggregation_factor = 16,
    habitat_threshold = 0.7
  ) %>%
  add_restorable_constraint(
    min_restore = 200,
    max_restore = 300,
  ) %>%
  add_compactness_constraint(1800, unit = "m")

# plot preprocessed data
plot(rast(list(p$data$existing_habitat, p$data$restorable_habitat)), nc = 2)

# print problem
print(p)

# Solve problem
s <- solve(p)
# plot solution
plot(s)

## End(Not run)

restoptr documentation built on Aug. 12, 2025, 1:08 a.m.