Parameter¶
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class ampl::Parameter : public ampl::BasicEntity<VariantRef>¶
Represents an AMPL parameter.
The values can be Double or String (in case of symbolic parameters).
Data can be assigned to the parameter using the methods Parameter::set() and Parameter::setValues directly from objects of this class or using AMPL::setData and a DataFrame object.
Instance access
Methods to access the instances which are part of this Entity
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inline VariantRef 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.
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inline VariantRef get(TupleRef index) const¶
Get the instance with the specified index.
- Parameters
index – The tuple specifying the index
- Throws
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
- Returns
The corresponding instance
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inline VariantRef get(VariantRef v1) const¶
Get the instance with the specified index.
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inline VariantRef get(VariantRef v1, VariantRef v2) const¶
Get the instance with the specified index.
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inline VariantRef get(VariantRef v1, VariantRef v2, VariantRef v3) const¶
Get the instance with the specified index.
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inline VariantRef get(VariantRef v1, VariantRef v2, VariantRef v3, VariantRef v4) const¶
Get the instance with the specified index.
- 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
- Throws
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
- Returns
The corresponding instance
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inline VariantRef operator[](TupleRef index) const¶
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inline VariantRef operator[](VariantRef v1) const¶
Public Types
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typedef internal::CountedIterator<internal::EntityWrapper<VariantRef>> iterator¶
Iterator for entities, represented by an iterator pointing to elements of type std::pair<TupleRef, InstanceClass>
Public Functions
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inline bool isSymbolic() const¶
Returns true if the parameter is declared as symbolic (can store both numerical and string values)
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inline bool hasDefault() const¶
Check if the parameter has a default initial value. In case of the following AMPL code:
param a; param b default a;
the function will return true for parameter
b
.- Returns
True if the parameter has a default initial value. Please note that if the parameter has a default expression which refers to another parameter which value is not defined, this will return true.
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inline void setValues(const Tuple indices[], internal::Args values, std::size_t nvalues)¶
Assign the values (string or double) to the parameter instances with the specified indices, equivalent to the AMPL code:
let {i in indices} par[i] := values[i];
- Parameters
indices – an array of indices of the instances to be set
values – values to set
nvalues – length of the values array
- Throws
logic_error – If called on a scalar parameter
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inline void setValues(std::size_t num_rows, internal::Args row_indices, std::size_t num_cols, internal::Args col_indices, const double *data, bool transpose)¶
Assign the specified values to a 2-d parameter, using the two dimensions as two indices.
For example, the \(m \times n\) matrix:
\[\begin{split}`A = \left( \begin{array}{cccc} a_{11} & a_{12} & ... & a_{1n} \\ a_{21} & a_{22} & ... & a_{2n} \\ ... & ... & ... & ... \\ a_{ m1} & a_{m2} & ... & a_{mn} \end{array} \right)`\end{split}\]can be assigned to the AMPL parameter:
param A {1..m, 1..n};
with the statementsetValues(A, false)
.As an example, to assign the matrix:
\[\begin{split}`A = \left( \begin{array}{cccc} 11 & 12 \\ 21 & 22 \\ 31 & 32 \end{array} \right)`\end{split}\]to the AMPL paramater:
param A{1..3, 1..2};
we can use the following code:ampl.eval("param a{1..3, 1..2};"); Parameter a = ampl.getParameter("a"); double values[6]; double rows[3]; double cols[2]; for (int i = 0; i < 3; i++) { rows[i] = i + 1; for (int j = 0; j < 2; j++) values[i * 2 + j] = (i + 1) * 10 + (j + 1); } for (int i = 0; i < 2; i++) cols[i] = i + 1; a.setValues(3, rows, 2, cols, values, false);
- Parameters
num_rows – Number of rows
row_indices – Indices of the rows
num_cols – Number of rows
col_indices – Indices of the rows
data – Values to be assigned
transpose – True to transpose the values in the matrix
- Throws
logic_error – If the method is called on a parameter which is not two-dimensional
invalid_argument – If the size of ‘values’ do not correspond to the sizes of the underlying indices
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inline void setValues(internal::Args values, std::size_t n)¶
Assign the specified n values to this parameter, assigning them to the parameter in the same order as the indices in the entity.
The number of values in the array must be equal to the specified size.
- Parameters
values – Values to be assigned.
n – Number of values to be assigned (must be equal to the number of instances in this parameter)
- Throws
invalid_argument – If trying to assign a string to a non symbolic parameter
logic_error – If the number of arguments is not equal to the number of instances in this parameter
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inline void set(VariantRef value)¶
Set the value of a scalar parameter.
- Throws
runtime_error – if the entity has been deleted in the underlying AMPL
logic_error – if this parameter is not scalar.
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inline void set(VariantRef index, VariantRef value)¶
Set the value of a single instance of this parameter.
- Throws
runtime_error – if the entity has been deleted in the underlying AMPL
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inline void set(TupleRef index, VariantRef value)¶
Set the value of a single instance of this parameter.
- Throws
runtime_error – if the entity has been deleted in the underlying AMPL
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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
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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
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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
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inline iterator find(TupleRef t) const¶
Searches the current entity for an instance with the specified index.
- Returns
an iterator to the wanted entity if found, otherwise an iterator to BasicEntity::end.
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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
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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
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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)
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inline std::string name() const¶
Get the name of this entity.
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inline std::size_t numInstances() const¶
Get the number of instances in this entity.
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inline std::string toString() const¶
Returns a string representation of this entity (its declaration)
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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.
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inline VariantRef get() const¶