An AMPL entity such as a parameter or a variable.
An entity can either represent a single instance of an AMPL algebraic entity or, if the corresponding declaration has an indexing expression, a mapping from keys to instances. In the derived classes, it has methods to access instance-level properties which can be used in case the represented entity is scalar.
To gain access to all the values in an entity (for all instances and all suffixes for that entities), use the function Entity::getValues().
The algebraic entities which currenty have an equivalent class in the API are:
Public Functions
-
inline std::string name() const
Get the name of this entity.
-
inline std::string type() const
Get the type of this entity.
-
inline 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
-
inline 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)
-
inline std::size_t numInstances() const
Get the number of instances in this entity.
-
inline 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
-
inline 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.
-
inline 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
-
inline 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
-
inline 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
-
inline std::string toString() const
Returns a string representation of this entity (its declaration)
-
template<class I>
inline Entity(BasicEntity<I> other)
Constructor to allow implicit conversion.
-
inline Entity &operator=(const Entity &rhs)
Assignment operator.
-
inline Entity()
Constructor to allow the construction of arrays of entities.
Friends
-
friend class AMPL
-
friend class DataFrame
-
friend class EntityArgs
-
friend class Instance