Hey Shin, thanks for that solution. I've made an edit to the question to show why I cannot Pivot and perform the Table Calc. I was surprised to see Pivoting as a need for the "Percent From" calc to work because I thought Tableau would perform the table calc on top of the values in the actual view. So I am struggling to understand why the data needs to be long instead of wide for this to work.
It sounds like that's not Tableau's task to create calculated filed, if you struggle to create such many calculated field??.
Anyway, generally speaking, having many measure value is not a good idea.
Tableau like dimensions, or in other words, without dimensions, Tableau does not show power of Viz creation.
Measure Names / Measure Values can not be referenced in calcs.
One can not use them in Table Calculations (in any Calculations, in fact).
So the brute force method remains, namely,
using a Parameter to chose the 'Baseline' Measure,
and writing a bunch of (simple) aggregations
to compare other Measures to the Baseline.
Please find the attached.
%ofFirstValue_v10.5_YF.twbx 40.8 KB