How to tweak Col Rank() to give consecutive numbers when using byCol

[#1]

I use Col Rank() to count runs:

Col Rank( :DateTime, :WaferID, <<Tie( "minimum" ) )

Each run may have multiple rows, which I can only separate by DateTime, so instead of writing long if statements, I used this formula.

The only thing that I don't like is the following. Let's say I have three rows generated per run, then my RunID column would look like:

1
1
1
4
4
4
7
7
7

and so on. I get where it comes from.

My question is - what would be the cleanest way to convert that to effectively 1, 1, 1, 2, 2, 2, 3, 3, 3?

[#2]

This formula appears to do what you want.  Others may have slicker ways

As Constant( Summarize( bygroup = by( :waferID ) ) );
Contains( bygroup, Char( :waferID) );

[#3 · Accepted solution]

I usually use Col Cumulative Sum (or other "tricks" for this)

Col Cumulative Sum(If(Row() == Col Min(Row(), :Column 1), 1,0))

Wish list:Add dense ranking to Ranking Tie and Col Rank functions 

[#4]

Dense ranking - We need it soo often.

I guess there are some JMP users who don't need dense ranking. For users who need it , it always feels like setting up a Turing machine.

Just imagine how cool it will feel if Dense ranking is available via new formula column.
Unfortunately, it's not possible to add such functions manually - JMP developers have to do it. They have to get aware there are users who need the function. Via Kudos ...

Please folks, take the 5 seconds, follow Jarmos link to the wish list and vote there!

[#5]

And if you have 5 more seconds, please also vote for:
https://community.jmp.com/t5/JMP-Wish-List/Col-N-Categories/idc-p/782236#M6115

[#6]

Thanks a lot for the idea!

My specific case is a little but more complicated, I have one or more categorical columns (i.e. different wafers running etc.)

So the formula ended up being this:

Col Cumulative Sum( If( Row() == Col Min( Row(), :Rank, :WaferID ), 1, 0 ), :WaferID )

..and you have to keep it as two separate columns, but it works!
Thanks!

[#7]

Table has to be sorted by your ranking variable, otherwise, if you have rank 2 before rank 1 - in the RunID they will be 1 and 2, respectively (because Col Cumulative Sum, that's why).

Not critical, but RunID order might be important.