calculating active users over the months

[Anonymous]

I have a dataset like below:

Activities
User	Date
A	1/1/2021
B	1/3/2021
C	1/5/2021
D	1/8/2021
E	2/3/2021

Contacts
User	Date
A	1/1/2021
B	1/4/2021
C	1/5/2021
E	1/18/2021
F	2/1/2021
A	2/9/2021

Calendar

Dates

1/1/2021

1/2/2021

1/3/2021

1/4/2021

1/5/2021

1/6/2021

1/7/2021

1/8/2021

Users
User	Category
A	ABC
B	ABC
C	SDF
D	ERT
E	ERT
F	QWE

Data relations:

• Users 1 to many Activities
• Users 1 to many Contats
• Calendar 1 to many Activities
• Calendar 1 to many Contats

Active user: is a user who performed at least one activity (Activities or Contacts) during the month. And with that he should receive the 1 that month

Inactive User: is a user who has not performed any activity. And with that he should receive the 0 that month

This is the example of the results table I want:

Active User x Months	Jan	Fer
A	1	1
B	1	0
C	1	0
D	1	0
E	0	1
F	0	1

#Activities_Users = CALCULATE(DISTINCTCOUNT('Activities'[User]),USERELATIONSHIP('Activities'[Date],'Calendar'[Date]))

I already tried to create a measure to count the active users of one of the tables, however I don't know how to do to evaluate the 2 tables

[daxer-almighty · Accepted solution]

// The Calendar table should be
// connected to both Contacts and
// Activities. No INACTIVE relationships
// should be present. Make sure that
// users are always selected from the
// Users dimension and time from Calendar.
// The fact tables should be hidden like
// Best Practices dictate. If you don't
// follow these, the formulas will not
// be working correctly.

[# Selected Users] = COUNTROWS( Users[User] )

[# Active Users] =
// An active user is one who
// in the selected period of
// time from Calendar has at
// least 1 entry in Activities or
// in Contacts.
COUNTROWS(
    DISTINCT(
        UNION(
            DISTINCT( Activities[User] ),
            DISTINCT( Contacts[User] )
        )
    )
)

[# Inactive Users] =
// In inactive user is one
// who has not been an active
// user in the selected period
// of time. In other words, subtract
// the active users from all the
// visible users in the current context.
[# Selected Users] - [# Active Users]