Identify shops with an inventory overlap

[MrHecht]

Dear Power BI community,

I am facing an issue where I need to compare which shops have released a specific product and compare which stores have an overlap with other products.

I would like to select a product and compare it across all stores where the product is released to find those stores where other products are also released.

Plain worded example: You are selling a very fancy coffee of a specfifc brand and compare if the same store is selling another brand of coffee 

I would like to display this information in a visual matrix, similar to the one shown below, and calculate ratios of shops that offer other products as well.

 

Disclaimer: Please ignore the conditional formatting of the cells for now!

Do you have any ideas on what measures I can use to achieve the comparison, so that I can identify the stores that only sell the specific product and those that offer more than one?

My idea of the end result should have a table like this and also to be able to calculate the 2 measures at the bottom: 

To achieve this, I have a table in long form that contains the product, the shop, and the product release date for that particular shop.

Example data set: 

 

The shop ID is linked to a shop dimension table that contains all the other information related to that particular shop. The external_id, in this particular use case, does not serve any function, and can be ignored if it is not useful in addressing the issue at hand.

Thank you so much for your time and please let me know if you need more context, 

Best, 

[lbendlin]

Sounds like you're on the right track.  What do you need help with?

[MrHecht]

Hello Ibendlin,

Thanks for answer!

I am having difficulty finding the DAX code that creates a selected product shop overview and allows me to see the overlap. I am currently stuck because my current matrix compares all products against each other, and I am unsure how to select a specific product.

It should be a dynamic function since I would like to change the selection of produts while using the report. 

[lbendlin]

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