Add constraint to limit the number of patches (habitat + restoration)

Add constraint to a restoration problem (restopt_problem()) object to specify the number of patches (habitat + restoration) that can be present within a solution.

Usage

add_nb_patches_constraint(problem, min_nb_patches, max_nb_patches)

Arguments

problem

restopt_problem() Restoration problem object.

min_nb_patches

integer Minimum number of patches.

max_nb_patches

integer Maximum number of patches.

Value

An updated restoration problem (restopt_problem()) object.

Details

A patch is a spatially continuous set of habitat and restoration planning units. This constraints applies on the union of the set of planning units that are selected for restoration and the initial habitat patches, and allows to specify a minimum and maximum number of patches. In practice, this constraint is useful to set simple targets for structural connectivity.

See also

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

Examples

if (FALSE) { # \dontrun{
# 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 = 10,
    max_restore = 100,
  ) %>%
  add_nb_patches_constraint(1, 1)

# 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)
} # }