LoopWhile
---------

LoopWhile iterates over a set of commands under the control of one or more logical expressions.  Since the logical conditions typically depend upon values in the data, commands executed in a LoopWhile cannot be anticipated and expanded in SDTL.

Properties
~~~~~~~~~~

.. csv-table::
   :header: "Name","Type","","Description"
   :widths: 15,10,5,100

   "Condition",":doc:`/composite-types/ExpressionBase/index`","0..1","Describes a condition required for the next iteration to begin.  "
   "EndCondition",":doc:`/composite-types/ExpressionBase/index`","0..1","Describes a condition that ends interation.  "
   "Commands",":doc:`/composite-types/CommandBase/index`","1..n","Commands within the loop."
   "Updated","`boolean <https://cogsdata.org/docs/modeler-guide/primitive-types/#boolean>`_","0..1","When TRUE, the loop has been expanded into separate commands."

Properties Inherited from TransformBase
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. csv-table::
   :header: "Name","Type","","Description"
   :widths: 15,10,5,100

   "ProducesDataframe",":doc:`/composite-types/DataframeDescription/index`","0..n","Signify the dataframe which this transform produces."
   "ConsumesDataframe",":doc:`/composite-types/DataframeDescription/index`","0..n","Signify the dataframe which this transform acts upon."

Properties Inherited from CommandBase
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. csv-table::
   :header: "Name","Type","","Description"
   :widths: 15,10,5,100

   "Command","`string <https://cogsdata.org/docs/modeler-guide/primitive-types/#string>`_","1..1","The type of command"
   "SourceInformation",":doc:`/composite-types/SourceInformation/index`","0..n","Information about the source of the command."
   "MessageText","`string <https://cogsdata.org/docs/modeler-guide/primitive-types/#string>`_","0..n","Adds a message that can be displayed with the command."


Item Type Hierarchy
~~~~~~~~~~~~~~~~~~~

* :doc:`/composite-types/CommandBase/index`
    * :doc:`/composite-types/TransformBase/index`
        * **LoopWhile**


Relationships
~~~~~~~~~~~~~
The following identified item types reference this type.

.. container:: image

   |stub|

.. |stub| image:: ../../images/LoopWhile.svg

SPSS_example_LoopWhile
~~~~~~~~~~~~~~~~~~~~~~

.. raw:: html

   <p>========= SPSS EXAMPLE ================</p>
   <p>LOOP IF (Y GT 10).
   COMPUTE X=X+1.
   END LOOP IF (X EQ 5).</p>
   <pre><code>{&quot;Command&quot;: &quot;LoopWhile&quot;,
         &quot;sourceInformation&quot;: {
            &quot;originalSourceText&quot;: &quot;LOOP IF (Y GT 10). 
   								COMPUTE X=X+1.
   								END LOOP IF (X EQ 5). &quot;
   							},
   &quot;Condition&quot;: 
   				{&quot;$type&quot;:&quot;FunctionCallExpression&quot;,
   				&quot;Function&quot;: &quot;gt&quot;,
   				&quot;IsSDTLName&quot;:&quot;True&quot;,
   				&quot;Arguments&quot;: [
   					{&quot;ArgumentName&quot;: &quot;EXP1&quot;,
   					&quot;ArgumentValue&quot;: 
   						{&quot;$type&quot;: &quot;VariableSymbolExpression&quot;,  &quot;VariableName&quot;: &quot;Y&quot;}
   					},
   					{&quot;ArgumentName&quot;: &quot;EXP2&quot;,
   					&quot;ArgumentValue&quot;: 
   						{&quot;$type&quot;: &quot;NumericConstantExpression&quot;,  &quot;Value&quot;: &quot;10&quot;}
   					}
   				]
   				},
   &quot;EndCondition&quot;:
   				{&quot;$type&quot;:&quot;FunctionCallExpression&quot;,
   				&quot;Function&quot;: &quot;eq&quot;,
   				&quot;IsSDTLName&quot;:&quot;True&quot;,
   				&quot;Arguments&quot;: [
   					{&quot;ArgumentName&quot;: &quot;EXP1&quot;,
   					&quot;ArgumentValue&quot;: 
   						{&quot;$type&quot;: &quot;VariableSymbolExpression&quot;,  &quot;VariableName&quot;: &quot;X&quot;}
   					},
   					{&quot;ArgumentName&quot;: &quot;EXP2&quot;,
   					&quot;ArgumentValue&quot;: 
   						{&quot;$type&quot;: &quot;NumericConstantExpression&quot;,  &quot;IteratorSymbolName&quot;: &quot;5&quot;}
   					}
   				]
   				},
   &quot;IteratorCommands:&quot; [
   	   {&quot;Command&quot;: &quot;compute&quot;,
           &quot;VariableName&quot;: 
   			{&quot;$type&quot;: &quot;VariableSymbolExpression&quot;,  &quot;VariableName&quot;: &quot;X&quot;},
           &quot;Expression&quot;: 
   		{&quot;$type&quot;:&quot;FunctionCallExpression&quot;,
   		   &quot;Function&quot;: &quot;Addition&quot;,
   		   &quot;IsSDTLName&quot;:&quot;True&quot;,
   		   &quot;Arguments&quot;: [
   		   {&quot;ArgumentName&quot;: &quot;EXP1&quot;,
   		   &quot;ArgumentValue&quot;: 
   				{&quot;$type&quot;: &quot;VariableSymbolExpression&quot;,  &quot;VariableName&quot;: &quot;X&quot;},
   				},
   		   {&quot;ArgumentName&quot;: &quot;EXP2&quot;,
   		   &quot;ArgumentValue&quot;: 
   				{&quot;$type&quot;: &quot;NumericConstantExpression&quot;,  &quot;IteratorSymbolName&quot;: &quot;1&quot;}
   			}
   			]
   		}
   		}
       ]
   
   }
   
   </code></pre>

Stata_example_LoopWhile
~~~~~~~~~~~~~~~~~~~~~~~

.. raw:: html

   <p>======== Stata EXAMPLE ===============</p>
   <pre><code>while `i'&lt;40 {
   	gen newvar`i' = runiform()
   	local i=`i'+1
   	}
   </code></pre>
   <pre><code>{&quot;Command&quot;: &quot;LoopWhile&quot;,
         &quot;sourceInformation&quot;: {
            &quot;originalSourceText&quot;: &quot;while `i'&lt;40 {
   								gen newvar`i' = runiform()
   								local i=`i'+1
   								}&quot;
   							},
   &quot;Condition&quot;: 
   				{&quot;$type&quot;:&quot;FunctionCallExpression&quot;,
   				&quot;Function&quot;: &quot;lt&quot;,
   				&quot;IsSDTLName&quot;:&quot;True&quot;,
   				&quot;Arguments&quot;: [
   					{&quot;ArgumentName&quot;: &quot;EXP1&quot;,
   					&quot;ArgumentValue&quot;: 
   						{&quot;$type&quot;: &quot;IteratorSymbolExpression&quot;,  &quot;IteratorSymbolName&quot;: &quot;i&quot;}
   					},
   					{&quot;ArgumentName&quot;: &quot;EXP2&quot;,
   					&quot;ArgumentValue&quot;: 
   						{&quot;$type&quot;: &quot;NumericConstantExpression&quot;,  &quot;Value&quot;: &quot;40&quot;}
   					}
   				]
   				},
   &quot;IteratorCommands:&quot; [
   	   {&quot;Command&quot;: &quot;compute&quot;,
           &quot;VariableName&quot;: 
   			{&quot;CompositeVariableName&quot;: 
   				{&quot;Stub&quot;: &quot;newvar&quot;,
   				 &quot;Postfix&quot;: 
   					{&quot;$type&quot;: &quot;IteratorSymbolExpression&quot;,  &quot;IteratorSymbolName&quot;: &quot;i&quot;}
   					}
   				},
   		&quot;Expression&quot;: 
   		{&quot;$type&quot;:&quot;FunctionCallExpression&quot;,
   		   &quot;Function&quot;: &quot;random_variable_uniform&quot;,
   		   &quot;IsSDTLName&quot;:&quot;True&quot;,
   		   &quot;Arguments&quot;: [
   		   {&quot;ArgumentName&quot;: &quot;EXP1&quot;,
   		   &quot;ArgumentValue&quot;: 
   				{&quot;$type&quot;: &quot;NumericConstantExpression&quot;,  &quot;Value&quot;: &quot;0&quot;},
   				},
   		   {&quot;ArgumentName&quot;: &quot;EXP2&quot;,
   		   &quot;ArgumentValue&quot;: 
   				{&quot;$type&quot;: &quot;NumericConstantExpression&quot;,  &quot;Value&quot;: &quot;1&quot;}
   			}
   			]
   		}
   		}
       ]
   
   }
   
   </code></pre>