Get objective values from a solution set

Extract objective values from the runs stored in a solutionset-class object.

Usage

get_objectives(x, format = c("wide", "long"))

Arguments

x

A solutionset-class object returned by solve.

format

Character. Output representation, either "long" or "wide". Defaults to "wide".

Value

If format = "long", a data.frame with columns solution_id, objective, and value.

If format = "wide", a data.frame with integer solution_id and one column per objective.

Details

Objective values are read from run-table columns named value_<objective>, where <objective> is the registered objective alias.

Runs without a stored solution may contain missing objective values. Filter the SolutionSet beforehand with solution_filter when only solved runs should be included.

Public objective tables are keyed by integer solution_id. Use get_runs when the relationship between attempted run_ids and stored solutions is required. In long format, every solution-objective combination occupies one row. In wide format, every stored solution occupies one row and every objective occupies one column.

See also

get_runs, frontier_extremes, frontier_distances

Examples

# Load a complete simulated planning problem.
example_data <- load_sim_multiaction()

problem <- create_problem(
  pu = example_data$planning_units,
  features = example_data$features,
  dist_features = example_data$dist_features,
  cost = "cost"
) |>
  add_actions(
    example_data$actions,
    cost = example_data$action_costs
  ) |>
  add_effects(
    example_data$effects,
    effect_type = "delta"
  ) |>
  add_constraint_targets_relative(0.05) |>
  add_objective_min_cost(alias = "cost", include_pu_cost = FALSE) |>
  add_objective_max_benefit(alias = "benefit") |>
  set_method_weighted_sum(
    aliases = c("cost", "benefit"),
    runs = set_runs_grid(n = 3),
    normalize_weights = TRUE
  )

if (requireNamespace("rcbc", quietly = TRUE)) {
  problem <- set_solver_cbc(
    problem,
    verbose = FALSE
  )

  solutions <- solve(problem)

  # Long format
  get_objectives(
    solutions,
    format = "long"
  )

  # Wide format
  get_objectives(
    solutions,
    format = "wide"
  )

  # Objective values from usable runs only
  usable_solutions <- solution_filter(
    solutions,
    feasible_only = TRUE
  )
  get_objectives(usable_solutions)
}
#>   solution_id   cost    benefit
#> 1           1   2.10  0.7616224
#> 2           2   2.73  2.2973781
#> 3           3 101.28 29.7962175