One difference I know exists from this workbook to the radial bar chart example on Interworks is that the start and end point have common dimensions across the board, while in this layout I have separate dimensions for each point (i.e. Start Provider Type vs. End Provider Type or Provider Name). Could this explain the lack of a line between each pair of points? If this is the case, are there ways to include these dimensions in calculations (i.e. CircleY and CircleX in the workbook) but not in what tells tableau to draw lines?
I am looking at your viz, and you have a Line chart that only has dots, but not the connections you would like to have. In fact, IMO, the lines are there, those dots are your lines, it's a Line chart, not a Circle chart, the lines are connecting each point to itself. IMO, the fact that you calculate dynamically the X and Y of your points on the circle in the view is nice but it may cause the lack of the lines. Here is an example using some data similar to yours, some small modifications made (in fact the second sheet uses the first 6 Dr., A to F from your data) and each Dr has his circle points X and Y calculated outside Tableau. Another way to do it maybe, have your usual input data stream (for Z doctors), have a second data stream that calculates X and Y on a circle for Z points, and join both data streams in Tableau, so that X and Y are added to your usual input data stream. Hope this helps you!
Just a quick note on how our data should be structured for Tableau to draw path maps
Most of the time our data is structured as below:
Start point Start Point X Start Point Y End Point End Point X End Point Y
However, for Tableau to draw the path between two objects the data needs to be as follows
Location X Y Path ID
Start Point Start Point X Start Point Y 1
End Point End point X End Point Y 2
When placing this in comparison with how I believe your data is structured from the following statement:
'while in this layout I have separate dimensions for each point (i.e. Start Provider Type vs. End Provider Type or Provider Name). Could this explain the lack of a line between each pair of points? '
I would suggest that this probably is the reason as to why there is a lack of a line between your two points. Hopefully the above will help illustrate how your data needs to be set.
Personally when doing these sorts of charts I do all the data preparation (getting the locations of points around a circle for example, and editing the data structure) in alteryx or Excel.
I have written a blog on how you would go about doing so in Excel which might be of help: #VizLikeAnArtist - Hub and Spoke Maps - The Data School
This may also be of help if you are handing with SQL: Tableau Tip: Create hub & spoke diagrams using the Path shelf