3 Replies Latest reply on Nov 29, 2016 3:01 AM by Simon Runc

    Bottom N values

    Daniel Higgins



      I have a dataset:


      Organisation Name on the Rows shelf (100 Organisations)

      Final Score as the Measure.

      Month as the Filter (filtered on September)


      I have sorted this dataset descending and filtered for the Bottom 10 results.


      However the Bottom 10 is being applied to the data as a whole and not looking at the month I have chosen.


      I have tried a few different things, searching for answers online, but for something that should be so simple (bizarre that the above doesn't work) I am really struggling to get this working.


      Thanks for your help!



        • 1. Re: Bottom N values
          Simon Runc

          hi Daniel,


          So this is caused by the Order of Filtering Operations within Tableau. Top/Bottom N, Sets and FIXED LoDs are all calculated before any "regular" dimension filters are applied (so the bottom N is calculated before your filters). You can, however, bump a filter up the pipeline by making it "in context"...this means that it gets applied before any Sets, Top N, or FIXED LoDs are calculated.



          Hope that helps

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          • 2. Re: Bottom N values
            Daniel Higgins

            Hi Simon,


            That is exactly what I wanted, thanks for the swift response.


            I've honestly searched loads online for an answer before coming here and I didn't come across that option once. You would think it should be the other way around and that option should have been applied automatically. One of Tableau's many idiosyncrasies.


            Thanks again,


            • 3. Re: Bottom N values
              Simon Runc

              No problem...yes this, data densification, and nested Table Calcs are the 3 areas where I think Tableau could do a better job communicating the features (although I think some are actually emergent features!) and how they work. Luckily there are lots of dedicated (and smart) users who have done the research...below is the "latest thinking" from Joshua Milligan on the entire filter/calculation pipeline (Top/Bottom N, and sets are where the FIXED LoDs are).


              Order-of-Operations - JM.png


              I find that it is actually useful to have this order as we can exploit it to do some cool things (eg. notice the final thing are Table Calc filters...this means by using a Table Calc as a filter we get the effect of filtering the view, but not the underlying data. So we can do things like YoY calcs, but only show the last year)...There was a talk on this at TC16 (available to view), but yes Tableau could do a better job documenting and communicating these (more obscure) workings!

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