Entity Class
============






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 :dn:method:`ampl.Entities.Entity.GetValues()`.
The algebraic entities which currenty have an equivalent class in the API are:

Variables (see :dn:class:`ampl.Entities.Variable`)

Constraints (see :dn:class:`ampl.Entities.Constraint`)

Objectives (see :dn:class:`ampl.Entities.Objective`)

Sets (see :dn:class:`ampl.Entities.Set`)

Parameters (see :dn:class:`ampl.Entities.Parameter`)


Namespace
    :dn:ns:`ampl.Entities`
Assemblies
    * AMPL

----

.. contents::
   :local:



Inheritance Hierarchy
---------------------


* :dn:cls:`System.Object`
* :dn:cls:`ampl.Entities.Entity`








Syntax
------

.. code-block:: csharp

    public class Entity : IEnumerable








.. dn:class:: ampl.Entities.Entity
    :hidden:

.. dn:class:: ampl.Entities.Entity

Methods
-------

.. dn:class:: ampl.Entities.Entity
    :noindex:
    :hidden:

    
    .. dn:method:: ampl.Entities.Entity.GetEnumerator()

        
        :rtype: System.Collections.IEnumerator

        
        .. code-block:: csharp

            public virtual IEnumerator GetEnumerator()
    
    .. dn:method:: ampl.Entities.Entity.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 members of the set, Note that it does not apply to indexed sets. See :dn:method:`ampl.SetInstance.GetValues`


        
        :rtype: ampl.DataFrame
        :return: A DataFrame containing the values for all instances

        
        .. code-block:: csharp

            public virtual DataFrame GetValues()
    
    .. dn:method:: ampl.Entities.Entity.GetValues(System.String[])

        

        
        Get the specified suffixes value for all instances in a DataFrame


        

        
        :param suffixes: Suffixes to get
        
        :type suffixes: System.String<System.String>[]
        :rtype: ampl.DataFrame
        :return: A DataFrame containing the specified values

        
        .. code-block:: csharp

            public DataFrame GetValues(params string[] suffixes)
    
    .. dn:method:: ampl.Entities.Entity.SetValues(ampl.DataFrame)

        

        
        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];`


        

        
        :param data: The data to set the entity to
        
        :type data: ampl.DataFrame

        
        .. code-block:: csharp

            public void SetValues(DataFrame data)
    
    .. dn:method:: ampl.Entities.Entity.ToString()

        

        
        Returns a textual representation of this entity


        
        :rtype: System.String

        
        .. code-block:: csharp

            public override string ToString()
    

Properties
----------

.. dn:class:: ampl.Entities.Entity
    :noindex:
    :hidden:

    
    .. dn:property:: ampl.Entities.Entity.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
        :dn:method:`ampl.Entities.Entity.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

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


        
        :rtype: System.Int32

        
        .. code-block:: csharp

            public int Indexarity { get; }
    
    .. dn:property:: ampl.Entities.Entity.IndexingSets

        

        
        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.
        Is equal to the string representation of the indexing sets for this entity or
        an empty array if the entity is scalar


        
        :rtype: System.String<System.String>[]

        
        .. code-block:: csharp

            public string[] IndexingSets { get; }
    
    .. dn:property:: ampl.Entities.Entity.IsScalar

        

        
        Check whether this entity is scalar. Equivalent to testing whether
        indexarity is equal to zero, is true if the entity is scalar 
        (not indexed over any set)


        
        :rtype: System.Boolean

        
        .. code-block:: csharp

            public bool IsScalar { get; }
    
    .. dn:property:: ampl.Entities.Entity.Name

        

        
        Get the name of this entity


        
        :rtype: System.String

        
        .. code-block:: csharp

            public string Name { get; }
    
    .. dn:property:: ampl.Entities.Entity.NumInstances

        

        
        Get the number of instances in this entity


        
        :rtype: System.Int32

        
        .. code-block:: csharp

            public int NumInstances { get; }