.. java:import:: java.util Iterator

Parameter
=========

.. java:package:: com.ampl
   :noindex:

.. java:type:: public class Parameter extends BasicEntity<Object>

   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 :java:ref:`set`, :java:ref:`setValues` directly from objects of this class or using :java:ref:`AMPL.setData` and a :java:ref:`DataFrame` object.

Constructors
------------
Parameter
^^^^^^^^^

.. java:constructor:: public Parameter(Entity entity)
   :outertype: Parameter

   Constructor

Parameter
^^^^^^^^^

.. java:constructor:: protected Parameter(ParameterBase impl)
   :outertype: Parameter

Methods
-------
get
^^^

.. java:method:: public Object get()
   :outertype: Parameter

   Get the value of a scalar parameter.

   :throws IllegalStateException: if the entity has been deleted in the underlying AMPL
   :throws UnsupportedOperationException: if this parameter is not scalar.

get
^^^

.. java:method:: public Object get(Object... key)
   :outertype: Parameter

   Get the value corresponding to key. The value will be a string or a double if the parameter is symbolic, a double otherwise. See :ref:`secAccessInstancesAndValues` for further information on how the key can be specified.

   :param key: The key to be found
   :throws IllegalStateException: if the entity has been deleted in the underlying AMPL interpreter
   :throws IllegalArgumentException: if trying to access an instance with the wrong number of keys (see :java:ref:`Entity.indexarity`)
   :return: The value of the parameter for the corresponding key (String or double) or ``null`` if the specified key is not found

get
^^^

.. java:method:: public Object get(Tuple key)
   :outertype: Parameter

   Get the value corresponding to key (passed as a Tuple). The value will be a string or a double if the parameter is symbolic, a double otherwise. See :ref:`secAccessInstancesAndValues` for further information on how the key can be specified.

   :param key: The key (as a tuple) to be found
   :throws IllegalStateException: if the entity has been deleted in the underlying AMPL interpreter
   :throws IllegalArgumentException: if trying to access an instance with the wrong number of keys (see :java:ref:`Entity.indexarity`)
   :return: The value of the parameter for the corresponding key (String or double) or ``null`` if the specified key is not found

hasDefault
^^^^^^^^^^

.. java:method:: public boolean hasDefault()
   :outertype: Parameter

   Check if the parameter has a default initial value. In case of the following AMPL code:

   .. parsed-literal::

      param a;
      param b default a;

   the function will return true for parameter \ ``b``\ .

   :return: 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.

impl
^^^^

.. java:method::  ParameterBase impl()
   :outertype: Parameter

isSymbolic
^^^^^^^^^^

.. java:method:: public boolean isSymbolic()
   :outertype: Parameter

   Check if the parameter is symbolic (aka can store strings)

   :return: True if the parameter is symbolic

iterator
^^^^^^^^

.. java:method:: @Override public Iterator<Object> iterator()
   :outertype: Parameter

set
^^^

.. java:method:: public void set(double index, double value)
   :outertype: Parameter

   Assign a value to the parameter at the specified index, equivalent to the AMPL code

   .. parsed-literal::

      let par[index] := value;

   :param index: Index (key) of instance to be set, can be a :java:ref:`Tuple` or an array for multidimensional parameters.
   :param value: Value to set.
   :throws UnsupportedOperationException: If called on a scalar parameter

set
^^^

.. java:method:: public void set(String index, double value)
   :outertype: Parameter

set
^^^

.. java:method:: public void set(Tuple index, double value)
   :outertype: Parameter

set
^^^

.. java:method:: public void set(double index, String value)
   :outertype: Parameter

   Assign a string to the parameter at the specified index, equivalent to the AMPL code:

   .. parsed-literal::

      let par[index] := value;

   :param index: Index (key) of instance to be set, can be a :java:ref:`Tuple` or an array for multidimensional parameters.
   :param value: Value to set.
   :throws UnsupportedOperationException: If called on a scalar parameter

set
^^^

.. java:method:: public void set(String index, String value)
   :outertype: Parameter

set
^^^

.. java:method:: public void set(Tuple index, String value)
   :outertype: Parameter

set
^^^

.. java:method:: public void set(double value)
   :outertype: Parameter

   Set the value of a scalar parameter.

   :throws IllegalStateException: if the entity has been deleted in the underlying AMPL
   :throws UnsupportedOperationException: if this parameter is not scalar.

set
^^^

.. java:method:: public void set(String value)
   :outertype: Parameter

   Set the value of a scalar parameter.

   :throws IllegalStateException: if the entity has been deleted in the underlying AMPL
   :throws UnsupportedOperationException: if the entity is not scalar.

setValues
^^^^^^^^^

.. java:method:: public void setValues(Tuple[] indices, double[] values)
   :outertype: Parameter

   Assign the (double) values to the parameter instances with the specified indices, equivalent to the AMPL code:

   .. parsed-literal::

      let {i in indices} par[i] := values[i];

   :param indices: Index (key) of instance to be set. Each item in the array can be a :java:ref:`Tuple` or an array of objects, in case of multidimensional array.
   :param values: Values to set.
   :throws UnsupportedOperationException: If called on a scalar parameter
   :throws IllegalArgumentException: if the dimension of some of the indices does not match the dimension of the indices of the parameter

setValues
^^^^^^^^^

.. java:method:: public void setValues(Tuple[] indices, String[] values)
   :outertype: Parameter

   Assign the values (string or double) to the parameter instances with the specified indices, equivalent to the AMPL code:

   .. parsed-literal::

      let {i in indices} par[i] := values[i];

   :param indices: Index (key) of instance to be set. Each item in the array can be a :java:ref:`Tuple` or an array of objects, in case of multidimensional array.
   :param values: Values to set.
   :throws UnsupportedOperationException: If called on a scalar parameter
   :throws IllegalArgumentException: If called with some string values on a non symbolic parameter or if the dimension of some of the indices does not match the dimension of the indices of the parameter

setValues
^^^^^^^^^

.. java:method:: public void setValues(double[] rowindices, double[] colindices, double[][] values, boolean transpose)
   :outertype: Parameter

   Assign the specified values to a 2-d parameter, using the two dimensions as two indices.

   For example, the :math:`m \times n` matrix: :math:`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)`

   can be assigned to the AMPL parameter: \ ``param A {1..m, 1..n};``\  with the statement \ ``setValues(A, false)``\ .

   As an example, to assign the matrix: :math:`A = \left( \begin{array}{cccc} 11 & 12 \\ 21 & 22 \\ 31 & 32 \end{array} \right)`

   to the AMPL paramater: \ ``param A{1..3, 1..2};``\  we can use the following code.

   .. parsed-literal::

      ampl.eval("param a{1..3, 1..2};");
      Parameter a = ampl.getParameter("a");
      double[][] values = new double[3][2];
      for (int i = 0; i < 3; i++)
        for (int j = 0; j < 2; j++)
          values[i][j] = (i + 1) * 10 + (j + 1);
      a.setValues(new double[] { 1, 2, 3 }, new double[] { 1, 2 }, values, false);

   :param values: Values to be assigned
   :param transpose: True to transpose the values in the matrix
   :throws UnsupportedOperationException: If the method is called on a parameter which is not two-dimensional
   :throws IllegalArgumentException: If the passed array of values is not rectangular or if the sizes of 'values' do not correspond to the sizes of the underlying indices

setValues
^^^^^^^^^

.. java:method:: public void setValues(String[] rowindices, String[] colindices, double[][] values, boolean transpose)
   :outertype: Parameter

setValues
^^^^^^^^^

.. java:method:: public void setValues(String... values)
   :outertype: Parameter

   Assign the specified 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 of the same size of the parameter, as this function will try to assign all values.

   :param values: Values to be assigned.
   :throws IllegalArgumentException: If multiple values are assigned to a scalar parameter, if the size of the ``values`` array is not equal to the size (number of instances) of the parameter or if trying to assign a string to a non symbolic parameter

setValues
^^^^^^^^^

.. java:method:: public void setValues(double... values)
   :outertype: Parameter

toString
^^^^^^^^

.. java:method:: @Override public String toString()
   :outertype: Parameter

   Returns a string representation of this parameter. Equivalent to the AMPL statement:

   .. parsed-literal::

      show parameterName;