I have your workbook open. I'm not clear what you need to do.
Are you saying you need to identify which members are new from one month to the next (within a given office)?
One concern I have here is this: You said, " ... Tableau can add that flag for me. "
Tableau doesn't write data. It can calculate values based on the data in the table, and you can display values on a sheet, but you can't update your data source with calculated values. If that's what you are looking to do, tableau is not your tool.
Thank you for boiling down my rambling - you've got it right - I need to identify which members are new from one month to the next within a given office.
I do understand that Tableau can't change my source data, but I hope there is some way to highlight the members in one month who are not present in the month I'm comparing to, whether that be a calculated field that returns "true" if the member was present and "false" if the member was not present or some other process.
In the attached I approached this in a way that is rather specific to your data.
I changed the sheet to put a measure on TEXT instead of the [Member Code] dimension.
Next I made a table calc ( in this case, RUNNING_SUM) that touches all the marks.
If you just did running_count(sum([Number of Records])) and put that on text, you would see the first row show 1, 1, 1. (It hits 1 on the first month because there is actual data there, and then remains at 1 because no more months have data.) You would see the next row display 1, 2, 3 because all three months have data.
My calc says:
if running_count(sum([Number of Records])) = 1 then "NEW" END
When I put that on COLORS, I get the first in any series displaying in orange, and the rest in blue. We don't see anything orange in the second and third months of the first row because no data is there to be colored (even though the value of running_count(sum([Number of Records])) is still 1 in the second and third months.)
The key here is using a table calc of some sort. Table calcs let us "see" other stuff in the table. Running_sum (of a value that is 1, such as number of records in this case) results in an incrementing count. We could also use RUNNING_COUNT to do the same thing. I could have used LOOKUP to look forward or backward in the table. Any of these can tell us what came before the cell we're currently sitting on.
Date Compare Test_v10.5.twbx 37.7 KB