Get the distinct count of applications used by users who used application A in Tableau - tableau-api

Question

I have a data set of users and the applications they used. For each application, I want to compute the total number of users who used only this application, who used this application + another application, +2 other applications,... At the end I need to get a treemap with where each square represents the total number of users who used only the application, the application + 1 application, + 2 applications,......and also compute the overlap percentage, that is how many users used only this application vs how many users used this application with another application. I could compute these metrics if I don't add the application constraint, that is compute the number of users who used one application, 2 applications, 3 applications, ..... and the overlap percentage was the percentage of users who used more than one application.
To do so,
I created a calculated field to count the total number of applications per user
Then I used this field to create bins, which gave me the total number of users who used 1 app, 2 apps, ..... N apps
I then ended up creating a treemap with those bins where the size of each square is the countD(users).
How to do the same but instead of only having (All) applications, be able to do it with only one application and their companion applications. I need an application selector, where each time I change the application, the treemap changes.

Answer 1

As you have not given sample data, I am proposing a solution assuming -
No rows are duplicate i.e. every user is associated with any unique application not more than once.
application types may not vary more than 15-20 (in that situation the solution may not work given the calculation range of tableau)
I have taken a sample data as follows-
Step-1 Create calculated field (CF) named as CF as -
// map every application with a number
CASE [Apl id]
WHEN 'apl1' THEN 1
WHEN 'apl2' THEN 2
WHEN 'apl3' THEN 3
WHEN 'apl4' THEN 4
WHEN 'apl5' THEN 5
END
You may add as many values as you have (all unique values of apl)
Step-2 add another CF CF1 as
// binary representation of each application used
{FIXED [User id]: sum(10^([CF]-1))}
Step-3 Create a parameter as
Step-4 add another CF CF2 as
// checking which user uses selected application mandatorily
If
LEFT(RIGHT(RIGHT('00000'+STR([CF1]),5), [Parameter 1]),1) = '1'
then 'Y' else 'N' end
Now you may build your view as shown below
Selecting parameter value will filter out those records where user is at least associated with selected value. Distinct count value will give you count of total applications used by these users. Now you can proceed to build your treemap. Please tell if any other help/explanation in the solution is required.
Note-1. This solution is proposed on binary logic (and hence the restriction). If you will see sum(CF1) values will give you a binary representation of applications used by that user where rightmost placeholder denotes that user is using apl1 yes (1) or not (0); and similarly onwards right to left.
Note-2: While calculating CF2 I have padded the CF1 values with leading zeros at most 5. This you have to change according to total count of your applications.