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

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

Methods to access the instances which are part of this Entity

inline ObjectiveInstance get() const#

Get the instance corresponding to a scalar entity.

Throws:

  • runtime_error – if the entity has been deleted in the underlying AMPL interpreter

  • logic_error – if the entity is not scalar

Returns:

The corresponding instance.

inline ObjectiveInstance operator[](Tuple index) const#
inline iterator begin() const#
inline iterator end() const#
inline iterator find(Tuple index) const#
inline std::enable_if<is_parameter_instance<T>::value, void>::type setInstances() const#
inline void setSuffix(std::string suffix, double value)#

Public Functions

inline double getDoubleSuffix(std::string suffix)#
inline std::string getStringSuffix(std::string suffix)#
inline double value() const#

Get the value of the objective instance.

inline std::string astatus() const#

Return the AMPL status.

inline std::string sstatus() const#

Return the solver status.

inline int exitcode() const#

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

inline std::string message() const#

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

inline std::string result() const#

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

inline void drop()#

Drop this objective.

inline void restore()#

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

inline bool minimization() const#

Get the sense of this objective.

Returns:

true if minimize, false if maximize

StringArray getIndexingSets() const#

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.

Returns:

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

DataFrame getValues() const#

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

Returns:

A DataFrame containing the values for all instances

DataFrame getValues(StringArgs suffixes) const#

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

Parameters:

suffixes – Suffixes to get

Returns:

A DataFrame containing the specified values

std::size_t indexarity() const#

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

Returns:

The sum of the dimensions of the indexing sets or 0 if the entity is not indexed

bool isScalar() const#

Check whether this entity is scalar.

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

Returns:

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

std::string name() const#

Get the name of this entity.

std::size_t numInstances() const#

Get the number of instances in this entity.

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

std::string toString() const#

Returns a string representation of this entity (its declaration).

StringArray xref() const#

Get the names of all entities which depend on this one.

Returns:

An array with the names of all entities which depend on this one.

void setSuffixes(DataFrame data)#