Send to port by percentage is not going be the percentages I entered

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Carolina C8 asked Dec 17, '20 Joerg Vogel commented Dec 17, '20

Send to port by percentage is not going be the percentages I entered

Hello,

I have been struggling to figure out why Flexsim won't follow the percentages I am entering so please help me! I made a small model to test how I will deal with rejects in my real model that I have attached. I have a table that outlines what percentage of items should go to queue 1 and what percentage should go to queue 2, and my source creates 100 items, but the model never distributes the items with the exact percentages.

I am using the send to port by percentage to try and get this to happen, and giving the items a label of "ProdType" that also corresponds to the column of the table. This is what I enter in the "percent" part:

Table("Percentages")[1][getlabel(item, "ProdType")]

I have played around with changing the "Use Random Stream" value, but none of the numbers I have tried split up the items the right way. I think the stream value is what is causing my issue but I am unsure how to fix that.

Here is the file: Yield Model.fsm

I would appreciate any help, thank you!

Software Version:

FlexSim 20.2.2

flexsim 20.2.2 send to port random stream percentage stream

1608167361058.png (7.8 KiB)

yield-model.fsm (36.6 KiB)

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Attachments: Up to 12 attachments (including images) can be used with a maximum of 23.8 MiB each and 47.7 MiB total.

Answer 1 · 2020-12-17T02:36:43Z

Matthew Gillespie answered Dec 17, '20 Joerg Vogel commented Dec 17, '20

The By Percentage options don't guarantee that exactly a certain percent will go to each port. Instead it gives each item a certain probability of going to that port. So when you say 80% go to port 1, then each item before it leaves is evaluated and has an 80% chance of going to port 1. But you could still get 10 items in a row that all go to port 2.

If you want to force a strict 80 out of every 100 items goes to port 1, then you need to use some other method that keeps track of how many items have gone to each port.

See this other thread for more discussion: https://answers.flexsim.com/questions/86660/decide-by-percentage-inaccuracy.html

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Carolina C8 commented · Dec 17, 2020 at 03:13 PM

Hello, thank you for replying!

I am still wondering how to send an exact proportion of product to each port. When I run my real model it won't always be in batches of 100, so I would like to be able to set it so exactly 80% of whatever the batch size goes to one queue, and 20% goes to the other. Is there a way to do that?

Also, how does changing the stream value affect it? When I put the stream value at 1 it got the closest to the values that I wanted.

Thank you!

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Joerg Vogel Carolina C8 commented · Dec 17, 2020 at 05:21 PM

The linked answer has some more comments and those describe other methods to accomplish a none even result.

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