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One method to show flow between products might be a Sankey Plot:
explained here: More options for your Tableau Sankey Diagram — DataBlick
Here are other links that might give ideas:
So a few ways of doing this:
- As Swaroop suggested, a Sankey plot would show this though you would have to limit the depth of the purchase in practice (so only look at the 1st, 2nd, and 3rd purchase for example). Now, historically these can be tricky to build, but the show me more extension in 2018.2 makes them incredibly easy
- Another way, might be a jitter plot and would probably my choice. For this we'd put the products on the x axis and the volume on the y as a measure. I'd then remove the aggregate measures and plot each purchase. To show the migration you could colour each mark based on the product and size if it is the customers first, second, etc purchase.
- A third way might be to look at this by tenure of the customer. Then you could plot tenure on the X axis and strength on the y, with product on colour (and coded appropriately). This would then show what the customer journey looks like since acquisition and you could add product to filter to give the result you are after.
Unfortunately you have a lot of options, instead the first thing I'd look at is why do want to look at initial purchase and then the migration? What questions is it that you are trying to answer? What will you do with that info once you have it? Once you understand those drivers, then it might well be that you are better off plotting two or three graphs to answer these specific queries in a dashboard, rather than a single graph to try and show everything.
Hopefully that gives you some ideas.