Add constraints to a conservation planning problem to ensure
that specific planning units are selected (or allocated
to a specific zone) in the solution. For example, it may be desirable to
lock in planning units that are inside existing protected areas so that the
solution fills in the gaps in the existing reserve network. If specific
planning units should be locked out of a solution, use
add_locked_out_constraints()
. For problems with non-binary
planning unit allocations (e.g., proportions), the
add_manual_locked_constraints()
function can be used to lock
planning unit allocations to a specific value.
Usage
add_locked_in_constraints(x, locked_in)
# S4 method for ConservationProblem,numeric
add_locked_in_constraints(x, locked_in)
# S4 method for ConservationProblem,logical
add_locked_in_constraints(x, locked_in)
# S4 method for ConservationProblem,matrix
add_locked_in_constraints(x, locked_in)
# S4 method for ConservationProblem,character
add_locked_in_constraints(x, locked_in)
# S4 method for ConservationProblem,Spatial
add_locked_in_constraints(x, locked_in)
# S4 method for ConservationProblem,sf
add_locked_in_constraints(x, locked_in)
# S4 method for ConservationProblem,Raster
add_locked_in_constraints(x, locked_in)
# S4 method for ConservationProblem,SpatRaster
add_locked_in_constraints(x, locked_in)
Arguments
- x
problem()
object.- locked_in
Object that determines which planning units should be locked in. See the Data format section for more information.
Value
An updated problem()
object with the constraints added to it.
Data format
The following formats can be used to lock in planning units.
locked_in
as anumeric
vectorcontaining
numeric
values that indicate which planning units should be locked for the solution. Ifx
hasdata.frame
planning units, then these values must refer to values in theid
column of the planning unit data. Alternatively, ifx
hassf::st_sf()
ormatrix
planning units, then these values must refer to the row numbers of the planning unit data. Additionally, ifx
hasnumeric
vector planning units, then these values must refer to the element indices of the planning unit data. Finally, ifx
hasterra::rast()
planning units, then these values must refer to cell indices. Note that this format is available for problems that contain a single zone.locked_in
as alogical
vectorcontaining
TRUE
and/orFALSE
values that indicate each if planning units should be locked in the solution. Note that the vector should have aTRUE
orFALSE
value for each and every planning unit in the argument tox
. This argument is only compatible with problems that contain a single zone.locked_in
as amatrix
objectcontaining
logical
(i.e.,TRUE
orFALSE
) values that indicate if certain planning units should be locked to a specific zone in the solution. Each row corresponds to a planning unit, each column corresponds to a zone, and each cell indicates if the planning unit should be locked to a given zone.locked_in
as acharacter
vectorcontaining column name(s) for the planning unit data in
x
that indicate if planning units should be locked for the solution. This format is only compatible if the argument tox
hassf::st_sf()
ordata.frame
planning units. The columns must havelogical
(i.e.,TRUE
orFALSE
) values indicating if planning units should be locked for the solution. For problems that contain a single zone, the argument todata
must contain a single column name. Otherwise, for problems that contain multiple zones, the argument todata
must contain a column name for each zone.locked_in
as asf::sf()
objectcontaining geometries that will be used to lock planning units for the solution. Specifically, planning units in
x
that spatially intersect withy
will be locked (perintersecting_units()
). Note that this option is only available for problems that contain a single management zone.locked_in
as aterra::rast()
objectcontaining cells used to lock planning units for the solution. Specifically, planning units in
x
that intersect with cells that have non-zero and non-NA
values are locked. For problems that contain multiple zones, thedata
object must contain a layer for each zone. Note that for multi-band arguments, each cell must only contain a non-zero value in a single band. Additionally, if the cost data inx
is aterra::rast()
object, we recommend standardizingNA
values in this dataset with the cost data. In other words, the cells inx
that haveNA
values should also haveNA
values in the locked data.
See also
See constraints for an overview of all functions for adding constraints.
Other constraints:
add_contiguity_constraints()
,
add_feature_contiguity_constraints()
,
add_linear_constraints()
,
add_locked_out_constraints()
,
add_mandatory_allocation_constraints()
,
add_manual_bounded_constraints()
,
add_manual_locked_constraints()
,
add_neighbor_constraints()
Examples
# \dontrun{
# set seed for reproducibility
set.seed(500)
# load data
sim_pu_polygons <- get_sim_pu_polygons()
sim_features <- get_sim_features()
sim_locked_in_raster <- get_sim_locked_in_raster()
sim_zones_pu_raster <- get_sim_zones_pu_raster()
sim_zones_pu_polygons <- get_sim_zones_pu_polygons()
sim_zones_features <- get_sim_zones_features()
# create minimal problem
p1 <-
problem(sim_pu_polygons, sim_features, "cost") %>%
add_min_set_objective() %>%
add_relative_targets(0.2) %>%
add_binary_decisions() %>%
add_default_solver(verbose = FALSE)
# create problem with added locked in constraints using integers
p2 <- p1 %>% add_locked_in_constraints(which(sim_pu_polygons$locked_in))
# create problem with added locked in constraints using a column name
p3 <- p1 %>% add_locked_in_constraints("locked_in")
# create problem with added locked in constraints using raster data
p4 <- p1 %>% add_locked_in_constraints(sim_locked_in_raster)
# create problem with added locked in constraints using spatial polygon data
locked_in <- sim_pu_polygons[sim_pu_polygons$locked_in == 1, ]
p5 <- p1 %>% add_locked_in_constraints(locked_in)
# solve problems
s1 <- solve(p1)
s2 <- solve(p2)
s3 <- solve(p3)
s4 <- solve(p4)
s5 <- solve(p5)
# create single object with all solutions
s6 <- sf::st_sf(
tibble::tibble(
s1 = s1$solution_1,
s2 = s2$solution_1,
s3 = s3$solution_1,
s4 = s4$solution_1,
s5 = s5$solution_1
),
geometry = sf::st_geometry(s1)
)
# plot solutions
plot(
s6,
main = c(
"none locked in", "locked in (integer input)",
"locked in (character input)", "locked in (raster input)",
"locked in (polygon input)"
)
)
# create minimal multi-zone problem with spatial data
p7 <-
problem(
sim_zones_pu_polygons, sim_zones_features,
cost_column = c("cost_1", "cost_2", "cost_3")
) %>%
add_min_set_objective() %>%
add_absolute_targets(matrix(rpois(15, 1), nrow = 5, ncol = 3)) %>%
add_binary_decisions() %>%
add_default_solver(verbose = FALSE)
# create multi-zone problem with locked in constraints using matrix data
locked_matrix <- as.matrix(sf::st_drop_geometry(
sim_zones_pu_polygons[, c("locked_1", "locked_2", "locked_3")]
))
p8 <- p7 %>% add_locked_in_constraints(locked_matrix)
# solve problem
s8 <- solve(p8)
# create new column representing the zone id that each planning unit
# was allocated to in the solution
s8$solution <- category_vector(sf::st_drop_geometry(
s8[, c("solution_1_zone_1", "solution_1_zone_2", "solution_1_zone_3")]
))
s8$solution <- factor(s8$solution)
# plot solution
plot(s8[ "solution"], axes = FALSE)
# create multi-zone problem with locked in constraints using column names
p9 <- p7 %>% add_locked_in_constraints(c("locked_1", "locked_2", "locked_3"))
# solve problem
s9 <- solve(p9)
# create new column representing the zone id that each planning unit
# was allocated to in the solution
s9$solution <- category_vector(sf::st_drop_geometry(
s9[, c("solution_1_zone_1", "solution_1_zone_2", "solution_1_zone_3")]
))
s9$solution[s9$solution == 1 & s9$solution_1_zone_1 == 0] <- 0
s9$solution <- factor(s9$solution)
# plot solution
plot(s9[, "solution"], axes = FALSE)
# create multi-zone problem with raster planning units
p10 <-
problem(sim_zones_pu_raster, sim_zones_features) %>%
add_min_set_objective() %>%
add_absolute_targets(matrix(rpois(15, 1), nrow = 5, ncol = 3)) %>%
add_binary_decisions() %>%
add_default_solver(verbose = FALSE)
# create multi-layer raster with locked in units
locked_in_raster <- sim_zones_pu_raster[[1]]
locked_in_raster[!is.na(locked_in_raster)] <- 0
locked_in_raster <- locked_in_raster[[c(1, 1, 1)]]
names(locked_in_raster) <- c("zone_1", "zone_2", "zone_3")
locked_in_raster[[1]][1] <- 1
locked_in_raster[[2]][2] <- 1
locked_in_raster[[3]][3] <- 1
# plot locked in raster
plot(locked_in_raster)
# add locked in raster units to problem
p10 <- p10 %>% add_locked_in_constraints(locked_in_raster)
# solve problem
s10 <- solve(p10)
# plot solution
plot(category_layer(s10), main = "solution", axes = FALSE)
# }