.. _secMATLABrefEntity:

Entity
======

.. mat:class:: Entity

This is the base class for all entities (:mat:class:`Variable` , :mat:class:`Constraint`, :mat:class:`Objective`,
:mat:class:`Parameter`, :mat:class:`Set`).
It can be used directly in methods such as :mat:meth:`AMPL.getEntity`, and it has the basic functionality 
shared for all Entity classes. 


get(key)
--------

.. mat:classmethod:: Entity.get(key)

**Syntax**
~~~~~~~~~~

``v = get(key)``
 
**Description**
~~~~~~~~~~~~~~~

``v = get(key)`` returns the instance corresponding to the specified key. Examples will be given for each specialized
Entity class. Note that the same effect can be achieved using MATLAB's indexing operator (round brackets).

**Input Arguments**
~~~~~~~~~~~~~~~~~~~

``key`` 
   The key of the instance to look up.

**Output Arguments**
~~~~~~~~~~~~~~~~~~~~

``v``
   The specified instance
   

getValues
---------

.. mat:classmethod:: Entity.getValues()

**Syntax**
~~~~~~~~~~

``df = c.getValues()``

``df = c.getValues(suffixes)``
 
**Description**
~~~~~~~~~~~~~~~

These functions return a dataframe with all the specified values of the entity, decoupled from the underlying AMPL. 
To gain access to the data, see :mat:class:`DataFrame`.

``c.getValues()`` gets the AMPL value (the default suffix for the current entity)

``c.getValues(suffixes)`` allows the user to specify which suffixes to get 


**Input Arguments**
~~~~~~~~~~~~~~~~~~~

``suffixes``
   Strings specifying which suffixes of the entity to get (see `AMPL built-in suffixes <http://www.ampl.com/NEW/suffbuiltin.html>`_).

**Output Arguments**
~~~~~~~~~~~~~~~~~~~~~~~~

``df``
   A dataframe containing all the specified values of the entity and its indices
   

hasIndexing
-----------

.. mat:classmethod:: Entity.hasIndexing()

**Syntax**
~~~~~~~~~~

``bool = hasIndexing``
 
**Description**
~~~~~~~~~~~~~~~

``hasIndexing`` check whether this entity has indexing or is scalar
  

**Output Arguments**
~~~~~~~~~~~~~~~~~~~~

``bool``
   1 if the entity has indexing, 0 if it is scalar
        

indexarity
----------

.. mat:classmethod:: Entity.indexarity()

**Syntax**
~~~~~~~~~~

``integer = indexarity``
 
**Description**
~~~~~~~~~~~~~~~

``indexarity`` Get the indexarity of this entity


**Output Arguments**
~~~~~~~~~~~~~~~~~~~~

``integer``
   The indexarity of this function, defined as the number of items 
   necessary to access an instance of this entity

**Example**
~~~~~~~~~~~
     
Indexarity of some functions:

.. code-block:: matlab

   ampl.eval('var x; var y{1..10}; var z{1..2, 3..4, 4..5};');
   ampl.getEntity('x').indexarity
   ampl.getEntity('y').indexarity
   ampl.getEntity('z').indexarity
   
gives::

    ans = 0
	ans = 1
	ans = 3
    


name
----

.. mat:classmethod:: Entity.name()

**Syntax**
~~~~~~~~~~

``n = name``
 
**Description**
~~~~~~~~~~~~~~~

``name`` Access the name of this entity


**Output Arguments**
~~~~~~~~~~~~~~~~~~~~

``n``
   The AMPL name (without indexing) of this entity
      

getIndices
----------

.. mat:classmethod:: Entity.getIndices()

**Syntax**
~~~~~~~~~~

``indices = getIndices`` 
 
**Description**
~~~~~~~~~~~~~~~

``getIndices`` get a cell array containing all the indices over which this entity is currently istantiated