If you look at the points that are marked, they are only the open air elements from the line - thus the problem is with the tunnel data in the equation (or at least that you can't get it in) because this then affects the pathing. This is going to be difficult unless your reshape your data as Tableau will need separate path information for line drawing - i.e. on the Northern Line, it needs to know to stop drawing the line at Hampstead (the end of the open air line), and start drawing a line at Golders Green (the start of the tunnel line) The overlap space is the line between these two points - you can't really have a gap in the line.
I took a different approach - instead of colouring the line, why not colour the stations on the dual axis ?
HTH 18.3 attached
Tube Map Forum.twbx 124.0 KB
Hi Peter, thanks for your help! Does that mean I'd have to start a new line, indicated by a new shape ID, every time the tube line goes from tunnel to open air and vice versa? As long as the gaps are really small, you wouldn't see them in a zoomed out map.
I'd really like to keep the information for all tunnels, not just the stations so don't mind reshaping the data.
Edit 1: I also noticed that if I take [Colour] off the marks shelf for "Map normal" (which doesn't contain sets and work perfectly fine) and add it back again, it breaks the map in tunnel view. Why is that? Can you replicate that error? As long as I've got that error, I can't even start building set actions because I don't understand what's wrong with my [Colour] field.
Edit 2: I got it to work! I had to set my [Set Action Colour] Field to MIN.
I got it to work for the tunnel view. When I hover over a line, it changes to the actual colour. Now I'd like to set this up for the normal view so I can see the tunnels for a specific line.
How do I set up my calculated field to consider the parameter? I tried
IF [Tube View Parameter]="Tunnel" AND [Line Set] AND [Line]="Central" THEN "Red"
ELSE [Open Air or Tunnel]
but that will break my set action and not return any colour at all. Any ideas, please?
Edit 1: Fixed it1
Tube Map Forum.twbx 147.4 KB