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

ConservationProblem-class 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 %).

Value

ConservationProblem-class object with the decisions added to it.

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. If multiple decisions are added to a problem object, then the last one to be added will be used.

Examples

Run this code

# NOT RUN {
# 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)
# }
# NOT RUN {
# solve problem
s1 <- solve(p1)

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