Objective

class Objective : public ampl::BasicEntity<ObjectiveInstance>

Represents an AMPL objective.

Note that, in case of a scalar objective, all the properties (corresponding to AMPL suffixes) of the objective instance can be accessed through methods like Objective::value(). The methods have the same name of the corresponding AMPL suffixes. See http://www.ampl.com/NEW/suffbuiltin.html for a list of the available suffixes.

All these methods throw an std::logic_error if called for a non scalar objective and an std::runtime_error if called on an entity which has been deleted in the underlying intepreter.

The instances, represented by the class ObjectiveInstance can be accessed via the operator Objective::operator[](), via the methods Objective::get() or via the iterators provided.

To gain access to all the values in an entity (for all instances and all suffixes for that entities), see Entity::getValues() and the DataFrame class.

Instance access

Methods to access the instances which are part of this Entity

ObjectiveInstance get() const

Get the instance corresponding to a scalar entity.

Return
The corresponding instance.
Exceptions
  • runtime_error: if the entity has been deleted in the underlying AMPL interpreter
  • logic_error: if the entity is not scalar

ObjectiveInstance get(TupleRef index) const

Get the instance with the specified index.

Return
The corresponding instance
Parameters
  • index: The tuple specifying the index
Exceptions
  • out_of_range: if an instance with the specified index does not exist
  • out_of_range: if the entity has been deleted in the underlying AMPL interpreter
  • ampl::UnsupportedOperationException: if the entity is scalar

ObjectiveInstance get(VariantRef v1) const

Get the instance with the specified index.

ObjectiveInstance get(VariantRef v1, VariantRef v2) const

Get the instance with the specified index.

ObjectiveInstance get(VariantRef v1, VariantRef v2, VariantRef v3) const

Get the instance with the specified index.

ObjectiveInstance get(VariantRef v1, VariantRef v2, VariantRef v3, VariantRef v4) const

Get the instance with the specified index.

Return
The corresponding instance
Parameters
  • v1: The VariantRef specifying the first element of the indexing tuple
  • v2: The VariantRef specifying the second element of the indexing tuple
  • v3: The VariantRef specifying the third element of the indexing tuple
  • v4: The VariantRef specifying the fourth element of the indexing tuple
Exceptions
  • out_of_range: if an instance with the specified index does not exist
  • runtime_error: if the entity has been deleted in the underlying AMPL interpreter
  • ampl::UnsupportedOperationException: if the entity is scalar

ObjectiveInstance operator[](TupleRef index) const
ObjectiveInstance operator[](VariantRef v1) const

Public Types

typedef internal::CountedIterator<internal::EntityWrapper<ObjectiveInstance>> iterator

Iterator for entities, represented by an iterator pointing to elements of type std::pair<TupleRef, InstanceClass>

Public Functions

double value() const

Get the value of the objective instance.

std::string astatus() const

Return the AMPL status.

std::string sstatus() const

Return the solver status.

int exitcode() const

Exit code returned by solver after most recent solve with this objective.

std::string message() const

Result message returned by solver after most recent solve with this objective.

std::string result() const

Result string returned by solver after most recent solve with this objective.

void drop()

Drop this objective.

void restore()

Restore this objective (if it had been dropped, no effect otherwise)

bool minimization() const

Get the sense of this objective.

Return
true if minimize, false if maximize

iterator begin()

Get an iterator pointing to the first instance in this entity.

iterator end()

Get an iterator pointing after the last instance in this entity.

iterator find(TupleRef t) const

Searches the current entity for an instance with the specified index.

Return
an iterator to the wanted entity if found, otherwise an iterator to BasicEntity::end.

DataFrame getValues()

Get the principal values of this entity as a DataFrame. The specific returned value depends on the type of entity (see list below).

For:
  • Variables and Objectives it returns the suffix val
  • Parameters it returns their values
  • Constraints it returns the suffix dual
  • Sets it returns all the of the set. Note that it does not
  • apply to indexed sets. See SetInstance::getValues
Return
A DataFrame containing the values for all instances

DataFrame getValues(StringArgs suffixes)

Get the specified suffixes value for all instances in a DataFrame.

Return
A DataFrame containing the specified values
Parameters
  • suffixes: Suffixes to get

void setValues(DataFrame data)

Set the values of this entiy to the correponding values of a DataFrame indexed over the same sets (or a subset). This function assigns the values in the first data column of the passed dataframe to the entity the function is called from. In particular, the statement:

x.setValues(y.getValues());

is semantically equivalent to the AMPL statement:

let {s in S} x[s] := y[s];
Parameters
  • data: The data to set the entity to

StringArray getIndexingSets()

Get the AMPL string representation of the sets on which this entity is indexed.

The obtained vector can be modified without any effect to the entity.

Return
The string representation of the indexing sets for this entity or an empty array if the entity is scalar

std::string name()

Get the name of this entity.

std::size_t indexarity()

Get the indexarity of this entity (sum of the dimensions of the indexing sets).

This value indicates the arity of the Tuple to be passed to the method BasicEntity::get() in order to access an instance of this entity. See the following AMPL examples 

var x;               # indexarity = 0
var y {1..2};        # indexarity = 1
var z {1..2,3..4};   # indexarity = 2
var zz {{(1, 2)}};   # indexarity = 2
Return
The sum of the dimensions of the indexing sets or 0 if the entity is not indexed

bool isScalar()

Check whether this entity is scalar.

Equivalent to testing whether indexarity() is equal to zero.

Return
True if the entity is scalar (not indexed over any set)

std::string toString()

Returns a string representation of this entity (its declaration)

std::size_t numInstances()

Get the number of instances in this entity.