Consecutively numbered Column

Question

Hello everybody,

for better understanding I attached an image showing my problem.

I do have a "column 1" in Excel or JMP showing numbers starting from 1. The numbers can repeat several times.

What I want to do now, is to insert a "column 2" which shows automatically consecutive numbers which refer to the numbers in column 1. For example I do have four times "1" in column 1, column 2 should show consecutive numbers (from 1 to 4) and so on. See see attached Image for better understanding.

I hope somebody is able to help me...the file consists of several hundred to thousand numbers.

Thanks in Advance.

Example.png

txnelson · Accepted Answer

Here is one way to write the formula for what you want

If( Row() == 1,
	counter = 0,
	If( Lag( :Column 1 ) == :Column 1,
		counter++,
		counter = 1
	)
);
counter;