EditingDecideModules < OpsRes

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---+ Editing Decide Modules

_Decide_ modules can be added to the flowchart view via dragging and dropping (see [[EditingCreateModules][Editing Create Modules]] for a demonstration) and edited by double clicking on the module. There are 4 types of _Decide_ modules.

---++ 2-way by Chance

This type of _Decide_ module will route entities one of two ways according to a given percentage. The percentage is specifed by the user and relates to the proprotion of entities that are routed to the _True_ exit point.

---++ 2-way by Condition

This type of _Decide_ module will route entities one of two ways depending on the condition. There are multiple types of conditions.

---+++ Variable

Arena evaluates a variable-based expression and routes to the _True_ exit point if the expression is true or the _False_ exit point otherwise.
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Attribute
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Arena evaluates an attribute-based expression and routes to the _True_ exit point if the expression is true or the _False_ exit point otherwise.

Consider the example of simulating queuing at a supermarket. If the entity attribute _QueueNumber_ is equal to 2 then that entity will be routed to the _True_ exit point which leads to processing at _Counter 2_.

<img width="539" alt="decide_module_model.JPG" src="%ATTACHURL%/decide_module_model.JPG" height="189" />

<img width="448" alt="Decide_module_by_Attribute.png" src="%ATTACHURL%/Decide_module_by_Attribute.png" height="257" />
---+++ Entity Type

Arena will route all of entites of the specifed entity type to the _True_ exit point and all other entity types to the _False_ exit point.

Consider the example of simluating an egg sorting factory. Suppose an egg can be a size 6 egg or a size 7 egg depending on its weight. If an egg has the _Entity Type_ defined as 'size 6 egg' then that entity will be routed to the _True_ exit point which leads to the _Collection of Size 6 Eggs_ while all other eggs are routed to the _False_ exit point which leads to the _Collection of Size 7 Eggs_.

<img width="586" alt="Decide_module_by_entity_type_example.PNG" src="%ATTACHURL%/Decide_module_by_entity_type_example.PNG" height="195" />

<img width="450" alt="Decide_Module_by_Entity_Type.PNG" src="%ATTACHURL%/Decide_Module_by_Entity_Type.PNG" height="257" />
---+++ Expression

Arena evaluates the expression and routes to the _True_ exit point if the expression is true or the _False_ exit point otherwise.

Consider the example of simulating the operations within an egg sorting factory over several weeks. Employees are rostered to work Monday to Friday however employees do not work on the weekend. The simluation must determine that it is not the weekend in order to simulate employees arriving for work. Using the built-in Arena variable =TNOW= (the current time) and the built-in Arena function =CalDayOfWeek(= ... =)= we can determine if the day is Sunday = 1, Monday = 2, etc (up to Saturday Day 7) the following _Decide_ module could be used to determine if the factory should open for business.

<img width="589" alt="Decide_module_by_expression_example.PNG" src="%ATTACHURL%/Decide_module_by_expression_example.PNG" height="198" />

<img width="458" alt="Decide_module_by_expression.PNG" src="%ATTACHURL%/Decide_module_by_expression.PNG" height="255" />

*NB*: In plain English the above expression says: If the current day of the week is less than 1 (which means it is a Sunday) or is greater than 7 (which means it is a Saturday) route to the _True_ exit point. 
---++ N-way by Chance

This type of _Decide_ module is an extension of the 2-way by Chance _Decide_ module. This type of _Decide_ module will route entities any number of ways specified by the user and according to a given percentage. The percentage is specifed by the user and relates to the proprotion of entities that are routed to that particular exit point.

---++ N-way by Condition

This type of _Decide_ module is an extension of the 2-way by Condition _Decide_ module.This type of _Decide_ module will route entities any number of ways specified by the user and according to a given condition. There are multiple types of conditions (as discussed above) and these are specifed by the user. Any entities that do not meet specified conditions are routed to the _False_ exit point.

-- Main.MichaelOSullivan - 25 Aug 2009
Topic revision: r18 - 2010-03-13 - MichaelOSullivan