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","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","1..1","The type of command"
   "SourceInformation",":doc:`/composite-types/SourceInformation/index`","0..n","Information about the source of the command."
   "MessageText","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
~~~~~~~~~~~~~


.. container:: image

   |stub|

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

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

========= SPSS EXAMPLE ================

LOOP IF (Y GT 10). 
COMPUTE X=X+1.
END LOOP IF (X EQ 5). 


```
{"Command": "LoopWhile",
      "sourceInformation": {
         "originalSourceText": "LOOP IF (Y GT 10). 
								COMPUTE X=X+1.
								END LOOP IF (X EQ 5). "
							},
"Condition": 
				{"$type":"FunctionCallExpression",
				"Function": "gt",
				"IsSDTLName":"True",
				"Arguments": [
					{"ArgumentName": "EXP1",
					"ArgumentValue": 
						{"$type": "VariableSymbolExpression",  "VariableName": "Y"}
					},
					{"ArgumentName": "EXP2",
					"ArgumentValue": 
						{"$type": "NumericConstantExpression",  "Value": "10"}
					}
				]
				},
"EndCondition":
				{"$type":"FunctionCallExpression",
				"Function": "eq",
				"IsSDTLName":"True",
				"Arguments": [
					{"ArgumentName": "EXP1",
					"ArgumentValue": 
						{"$type": "VariableSymbolExpression",  "VariableName": "X"}
					},
					{"ArgumentName": "EXP2",
					"ArgumentValue": 
						{"$type": "NumericConstantExpression",  "IteratorSymbolName": "5"}
					}
				]
				},
"IteratorCommands:" [
	   {"Command": "compute",
        "VariableName": 
			{"$type": "VariableSymbolExpression",  "VariableName": "X"},
        "Expression": 
		{"$type":"FunctionCallExpression",
		   "Function": "Addition",
		   "IsSDTLName":"True",
		   "Arguments": [
		   {"ArgumentName": "EXP1",
		   "ArgumentValue": 
				{"$type": "VariableSymbolExpression",  "VariableName": "X"},
				},
		   {"ArgumentName": "EXP2",
		   "ArgumentValue": 
				{"$type": "NumericConstantExpression",  "IteratorSymbolName": "1"}
			}
			]
		}
		}
    ]

}

```






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

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

}

```