number_of_zones(x)

## S4 method for signature 'ConservationProblem'
number_of_zones(x)

## S4 method for signature 'OptimizationProblem'
number_of_zones(x)

## S4 method for signature 'ZonesRaster'
number_of_zones(x)

## S4 method for signature 'ZonesCharacter'
number_of_zones(x)

# load data
data(sim_pu_zones_stack, sim_features_zones)

# print number of zones in a Zones object
print(number_of_zones(sim_features_zones))
# create problem with multiple zones
p <- problem(sim_pu_zones_stack, sim_features_zones) %>%
     add_min_set_objective() %>%
     add_relative_targets(matrix(0.2, ncol = 3, nrow = 5)) %>%
     add_binary_decisions()

# print number of zones in the problem
print(number_of_zones(p))