You could use this:  {FIXED [Id No]:MIN([Code])}

Hi Daniel!

Good to see out and about in the community again!

I have a feeling that {FIXED [Id No]:MIN([Code])} will result in a MIN(code) alphabetically and not literally the 1st occurence. So if LS corresponds to month 4 and OP corresponds to month 1 then your formula would still yield LS not OP. I don't have access to Tableau right now so I can't really test anything. But just by looking at it,  feel like this wouldn't work.

Thank you for keeping me honest Pooja...and good to be back

I was trying to do round hole/square peg and make LoD work.  May need to play with it but this will work assuming you don't find something else I missed or can write it more eloquently than I.

You will need to write the following table calc's:

WINDOW_MIN(IF NOT ISNULL(ATTR([Code])) THEN INDEX() END)  -- This one will give us the first instance of a non null

LOOKUP(ATTR([Code]),[c.calc2]-INDEX()) -- This will lookup up the code from the above calc

You'll need to edit the last calc when you put it on the text shelf:

You'll need to go into advanced for both calc's then set addressing to id, month, code and finally restarting at id:

Check out this to see if it works for you

https://public.tableau.com/views/FirstValueasMonthlyValue/Sheet1?:embed=y&:display_count=yes&:showTabs=y

Use Tableau Public to open it.

Created two calc fields, both compute using Month:

[Min Month]

WINDOW_MIN( if Not ISNULL( ATTR( [Code] )  )then ATTR( [Month] ) END)

[Month_Code]

WINDOW_MAX(if [Min Month] =ATTR([Month]) then ATTR( [Code] )END)

haha that explanation turned out to be longer than expected

How about this?

IF [Month] = IF NOT isnull([Code]) then { fixed [ID_no] : min([Month]) } END then [Code] end

I tried something like that (several flavors) but couldn't get it to work with LoD.  I was hoping yours worked but it got the same null result as I was getting.

Still wondering if LoD is possible or even worth it over doing a table calc in this scenario.

Put 2 solutions into this viz

https://public.tableau.com/views/FirstValueasMonthlyValue/Sheet1?:embed=y&:display_count=yes&:showTabs=y

One with LOD, the other without.

hmm thanks for testing that. I feel like table calc is such an overkill for a simple ask. Maybe something like this?

IF [Month] = {FIXED [ID no] : MIN(IF NOT ISNULL([Code]) then [Month] END) } THEN [Code] END

If not, I will fiddle with it tomorrow. But I do feel like, LOD would be the way to go!

Looks like table calc is unavoidable as Alexander Mou was able to do it using both LoD/table calc. 

I don't see a benefit of one over the other so it's really dealers choice IMHO.

Cynthia (and all involved)... I have an LOD solution that works for your use case. Just a little tricky because it involves nesting LOD calcs, To keep myself sane, I created the calculations in two steps.

EDIT: Hadn't seen Alexander's solution, which uses LOD/table calculation hybrid - also a viable solution

Step 1

Create an LOD calculation [First Month] that returns the First Month with a non-NULL Code for any ID. The formula is:

{ FIXED [ID no] : MIN(IF NOT ISNULL([Code]) THEN [Month] END) }

Step 2

Create a 2nd LOD calculation [First Code] that returns the Code of the First Month. The formula:

{ FIXED [ID no] : MIN(IIF([Month] = [First Month], [Code], NULL)) }

Note that MIN could also be MAX, assuming there is only one non-NULL Code for any given ID no and Month. It is just returning the Code for the month of the first LOD calculation [First Month].

Step 3

Verify the results.

Workbook attached,

-Steve

Steve,

Good trick of using LOD to replace the window function in the second step!

It does the same thing.

Table calc filters work fine.

Depends on what you want to.

On Thursday, February 11, 2016, Cynthia Wang <tableaucommunity@tableau.com>