prioritizr: add_semicontinuous_decisions – R documentation

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add_semicontinuous_decisions

Add semi-continuous decisions

Description

Add a semi-continuous decision to a conservation planning problem(). This is a relaxed decision where a part of a planning unit can be prioritized, as opposed to the entire planning unit, which is the default function (see add_binary_decisions()). This decision is similar to the add_proportion_decisions() function except that it has an upper bound parameter. By default, the decision can range from prioritizing none (0%) to all (100%) of a planning unit. However, an upper bound can be specified to ensure that at most only a fraction (e.g. 80%) of a planning unit can be preserved. This type of decision may be useful when it is not practical to conserve entire planning units.

Usage

add_semicontinuous_decisions(x, upper_limit)

Arguments

`x`	`problem()` (i.e. `ConservationProblem`) object.
`upper_limit`	`numeric` value specifying the maximum proportion of a planning unit that can be reserved (e.g. set to 0.8 for 80%).

Details

Conservation planning problems involve making decisions on planning units. These decisions are then associated with actions (e.g. turning a planning unit into a protected area). If no decision is explicitly added to a problem, then the binary decision class will be used by default. Only a single decision should be added to a ConservationProblem object. Note that if multiple decisions are added to a problem object, then the last one to be added will be used.

Value

Object (i.e. ConservationProblem) with the decisions added to it.

Examples

# set seed for reproducibility
set.seed(500)

# load data
data(sim_pu_raster, sim_features, sim_pu_zones_stack, sim_features_zones)

# create minimal problem with semi-continuous decisions
p1 <- problem(sim_pu_raster, sim_features) %>%
      add_min_set_objective() %>%
      add_relative_targets(0.1) %>%
      add_semicontinuous_decisions(0.5) %>%
      add_default_solver(verbose = FALSE)
## Not run: 
# solve problem
s1 <- solve(p1)

# plot solutions
plot(s1, main = "solution")

## End(Not run)
# build multi-zone conservation problem with semi-continuous decisions
p2 <- problem(sim_pu_zones_stack, sim_features_zones) %>%
      add_min_set_objective() %>%
      add_relative_targets(matrix(runif(15, 0.1, 0.2), nrow = 5,
                                  ncol = 3)) %>%
      add_semicontinuous_decisions(0.5) %>%
      add_default_solver(verbose = FALSE)
## Not run: 
# solve the problem
s2 <- solve(p2)

# print solution
print(s2)

# plot solution
# panels show the proportion of each planning unit allocated to each zone
plot(s2, axes = FALSE, box = FALSE)

## End(Not run)

prioritizr

Systematic Conservation Prioritization in R

v7.0.1

GPL-3

Authors

Jeffrey O Hanson [aut] (<https://orcid.org/0000-0002-4716-6134>), Richard Schuster [aut, cre] (<https://orcid.org/0000-0003-3191-7869>), Nina Morrell [aut], Matthew Strimas-Mackey [aut] (<https://orcid.org/0000-0001-8929-7776>), Matthew E Watts [aut], Peter Arcese [aut] (<https://orcid.org/0000-0002-8097-482X>), Joseph Bennett [aut] (<https://orcid.org/0000-0002-3901-9513>), Hugh P Possingham [aut] (<https://orcid.org/0000-0001-7755-996X>)

Initial release