Does this fit your need?
There's probably a number of approaches, but what I did was to split the dates into two reporting periods, up to the end of 2016 and everything thereafter. By adding this to the view, it created a pane per reporting period.
When you drag the reference line onto the view, you can select whether to add it to the whole table, each pane or each cell. Now that we have two reporting periods (panes), you can drag min and max to each pane and it is automatically calculated per pane.
Then right-click on the date axis to edit it and select Independent axis ranges to bring the two graphs closer together. There's almost certainly a more elegant method that would give you a continuous data axis, but I hope this is enough for now!
This definitely looks promising! Thanks!. Unfortunately I couldn't open your attached version because you have a different version than me. How did you go about making the different date panes? Is it a parameter or a calculated field perhaps?
I used a calculated field. What version do you have? I can save it as a previous version and upload it in the morning.
My calculated field, [Reporting Period] is:
IF YEAR(DATETRUNC('day', [Order Date]))<=2016
THEN "Up to 2016"
ELSE "Post 2016"
Note that the dividing point of end 2016 could easily be replaced by a parameter set by the user. Removing the headings for reporting period may or may not make sense, depending on the purpose of the report.
I've attached the file with version 2019.1 compatibility. Hopefully this is OK for you to open.
The version I have is 2019.2.3. I haven't had a chance to mess around in Tableau as work picked up substantially but thank you very much for your contributions.
The version I uploaded should work then!
Once you have tested it and should it suit your needs, please mark the answer as correct as this helps other users find the solution in the future.
If it's not quite there yet, please let me know!
It's been bothering me that I was not able to get a continuous timeline for the graph above. I just watched this video from Andy Kriebel:How to Convert a Reference Line into a Level of Detail Expression - YouTube
It gave me an idea, the result of which is:
It's a bit more complicated, needing LODs for the max/min lines. It also required a bit of dashboard trickery to get the labels on the max/min, but I like the result better. It still uses the reporting period calculated field
By the way, I agree that some things in Tableau seem ridiculously difficult and complicated for what they are. In my experience, this can be either (a) because it is difficult and shouldn't be - see the ideas section in the forum - or (b) not really, it just needs a different way of thinking. Tableau is not Excel! They do different jobs. Tableau also requires you to have a deep understanding of your data.
On the other hand, Tableau can also be mind-bogglingly brilliant and simple and can produce amazing results. It depends on what you're trying to do
I'd put this case somewhere in the middle. Updated example attached.
So using the calculated field to create the two different panes is something along the lines of what I'm looking for. I'm running into two problems though.
1. I need the panes to be separated by a the specific date of 3/11/2020 and not a year. For some reason I can't get tableau to recognize my date function. I must be unfamiliar with what tableau is looking for but its not recognizing 3/11/2020.
2. I need my reference max and min lines to refer to distinct constants. For example pane one max and min are 280,000,000 and 140,000,000 while pane two max and min are 1,200,000,000 and 885,000,000 respectively. Every time I create a constant reference line for each pane is puts the same reference line across both panes.
I apologize for all the asks and I appreciate all the help and correspondence. I just wish I could just draw 4 separate horizontal lines haha.