
1. Re: Can we apply lookup and table calculations between two data sources in Tableau Prep?
Rory Wallis Oct 10, 2018 4:48 AM (in response to Kristi Boesen)Hi Kristi,
Is this what you're after?
Rory

Joining Solution.tflx 15.6 KB


2. Re: Can we apply lookup and table calculations between two data sources in Tableau Prep?
Jim Dehner Oct 10, 2018 4:57 AM (in response to Kristi Boesen)Good morning Kristi
I don't think you will be able to use a table calculation in Prep  table calculations operating on the underlying table for each view in Tableau proper 
In prep you are reshaping and cleaning data that you can then load into Tableau for further analysis 
Jim
If this posts assists in resolving the question, please mark it helpful or as the 'correct answer' if it resolves the question. This will help other users find the same answer/resolution. Thank you.

3. Re: Can we apply lookup and table calculations between two data sources in Tableau Prep?
Rory Wallis Oct 10, 2018 5:01 AM (in response to Jim Dehner)Agreed. I was only able to come to a solution if the percentages are already known. If the table calculation data is already included in the data set then you can do it. If not then there isn't enough there.
Rory

4. Re: Can we apply lookup and table calculations between two data sources in Tableau Prep?
Kristi Boesen Oct 10, 2018 5:22 AM (in response to Rory Wallis)Thanks Rory & Jim for taking time to consider this!
Yes, the challenge is about 1) calculating the % total impressions distribution for a set of creative_id rows within a placement_Id, and then 2) referring to another source to get the total # views value that would be distributed across the creative_id rows according to those % calculations. Unfortunately, the distribution is not known because it can vary by placement and therefore must be uniquely calculated for each placement_id and the creative_ids within.
In the past, I have accomplished this kind of clean up manually using nested vlookup and sumif formulas in Excel. I'm hoping to avoid that and build the cleanup into the Tableau Prep flow. To your point "if the table calculation data is already included in the data set then you can do it..."  perhaps I can create a field for the % impressions distribution calculation in the initial data source; and if I do that, I'm still wondering how to lookup that total # views value from another data source in the Tableau Prep flow to use for my final calculation across the creative_ids. Is there such a thing as lookup logic across data sources in Tableau Prep, or would I need to join the sources to do that?
Thanks again for your help!
Kristi 
5. Re: Can we apply lookup and table calculations between two data sources in Tableau Prep?
Rory Wallis Oct 10, 2018 5:27 AM (in response to Kristi Boesen)Hi Kristi,
If you work of the idea that the % dist is already included in the data source then the flow I posted should cover everything else. Follow the steps there and it should hopefully give you what you need. In effect, you just need to join the two data sources together.
Rory 
6. Re: Can we apply lookup and table calculations between two data sources in Tableau Prep?
Jim Dehner Oct 10, 2018 5:42 AM (in response to Kristi Boesen)Kristi
Joining 2 tables is the equivalent of an excel lookup  when you join the tables the join variable is equivalent to the "lookup variable' in excel  the remaining dimensions (columns in excel) are equivalent to adding additional columns to your excel table 
does that make sense?
Jim
If this posts assists in resolving the question, please mark it helpful or as the 'correct answer' if it resolves the question. This will help other users find the same answer/resolution. Thank you.