uk.ac.ucl.cs.uml.jmi.BehavioralElements.Actions.CollectionActions
Interface ReduceAction
- All Superinterfaces:
- Action, CollectionAction, Element, ExtObject, ModelElement, javax.jmi.reflect.RefBaseObject, javax.jmi.reflect.RefFeatured, javax.jmi.reflect.RefObject
- All Known Implementing Classes:
- ReduceAction_Impl
public interface ReduceAction
- extends CollectionAction
The reduce action applies an associative binary subaction
repeatedly to adjacent pairs of slices from the input
collections, until the (intermediate working) collection is
reduced to a single slice of scalar values, which together
constitute the output values of the reduce action. The order in
which the subaction is applied to pairs of values is
indeterminate, and does not affect the ultimate result if the
action is associative, unless the subactions are not isolated
from each other, in which case the result is unpredictable.
As an example, consider a collection comprising four integers
in order: 2, 7, 5 and -3. The result of applying the reduce
action to this collection with the binary associative subaction
Addition is the scalar 9. This can be computed by any of the
following orderings: ( ( (2+7) + 5) + -3) = 11; (2 + (7 + (5 +
-3))) = 11; ((2 + 7) + (5 + -3)) = 11. When the subaction is
symmetric, as with addition, the order of the elements in the
collection is not important. However, some associative
operations are not symmetric, such as matrix multiplication, so
A × B is not the same as B × A. In these cases, the concept of
adjacency of the elements and the order in which they appear is
critical. The reduce action requires a subaction, which must be
a binary associative operator. Each of the two inputs to the
subaction is a slice from the input collections to the reduce
action. For example, to sum all the balances for a customer’s
account, the reduce action has a single input collection of
account balances, and a single scalar output, the sum of those
balances, which must necessarily be of the same type. Each of
the two inputs to the subaction, Addition, takes "a slice from
the input collections to the reduce action", which in this case
is a single account balance on each input. The output is a tuple
ith the same structure: a balance. When the reduce action has
several input collections, then one slice across all collections
will be one input to the subaction and another slice will
constitute the other input.
The reduce action executes the subaction one fewer time than the
size of the input collections., because it operates on adjacent
pairs of slices from the input collections. The output of the
subaction conceptually replaces the two input slices in the
collection of tuples, so the subaction can be applied repeatedly
to pairs of slices until a single slice remains. Its value is
place on the result output pins of the overall reduce action as
scalars. In other words, the reduce action serves to reduce a
collection of values to a single value by repeated application
of a binary function.
If the subaction accesses values from outside the reduce action,
uch values will be the same for all the concurrent subaction
executions during a single execution of the reduce action. No
output pins of the subaction may be connected outside the reduce
action.
The isUnordered attribute states that the reduction can be
applied to the slices in any order, even though the ordering of
elements in each collection is still used to match corresponding
elements into slices. This will be mathematically valid if the
subaction is symmetric and the actions are isolated.
| Methods inherited from interface uk.ac.ucl.cs.uml.jmi.BehavioralElements.Actions.ActionFoundation.Action |
getAntecedent, getAvailableInput, getAvailableOutput, getConsequent, getGroup, getInputPin, getIsReadOnly, getJumpHandler, getOutputPin, setGroup, setIsReadOnly |
| Methods inherited from interface uk.ac.ucl.cs.uml.jmi.Foundation.Core.ModelElement |
getAsArgument, getBehavior, getClientDependency, getComment, getConstraint, getContainer, getDefaultElement, getIsSpecification, getName, getNamespace, getPackage, getPresentation, getReferenceTag, getSourceFlow, getStereotype, getSupplierDependency, getTaggedValue, getTargetFlow, getTemplate, getTemplateArgument, getTemplateParameter, getVisibility, setDefaultElement, setIsSpecification, setName, setNamespace, setTemplate, setVisibility |
| Methods inherited from interface javax.jmi.reflect.RefObject |
refClass, refDelete, refImmediateComposite, refIsInstanceOf, refOutermostComposite |
| Methods inherited from interface javax.jmi.reflect.RefFeatured |
refGetValue, refGetValue, refInvokeOperation, refInvokeOperation, refSetValue, refSetValue |
| Methods inherited from interface javax.jmi.reflect.RefBaseObject |
equals, hashCode, refImmediatePackage, refMetaObject, refMofId, refOutermostPackage, refVerifyConstraints |
getIsUnordered
boolean getIsUnordered()
throws javax.jmi.reflect.JmiException
- Throws:
javax.jmi.reflect.JmiException
setIsUnordered
void setIsUnordered(boolean isUnordered)
throws javax.jmi.reflect.JmiException
- Setter for atomic property isUnordered)
- Throws:
javax.jmi.reflect.JmiException
getSuboutput
List getSuboutput()
throws javax.jmi.reflect.JmiException
- Throws:
javax.jmi.reflect.JmiException
getArgument
List getArgument()
throws javax.jmi.reflect.JmiException
- Throws:
javax.jmi.reflect.JmiException
getLeftSubinput
List getLeftSubinput()
throws javax.jmi.reflect.JmiException
- Throws:
javax.jmi.reflect.JmiException
getRightSubinput
List getRightSubinput()
throws javax.jmi.reflect.JmiException
- Throws:
javax.jmi.reflect.JmiException