show growth over time

[nick9one1]

I have a log table that contains an action, user id and date/time. 

I would like to produce a line chart that shows continual user growth over time. 

the Title column would need to only show the first login for each user. So that would be the first instance of 'launched app'.

How can I achieve this? Thank you 

[nick9one1 · Accepted solution]

I think I've figured this out. 

I created a column that has a 1 for the first appearance of each user email;

First Login = 
VAR _class =
    CALCULATE(
        MIN('Log'[Date]),
        ALLEXCEPT('Log', 'Log'[email])
    )
RETURN
    IF('Log'[Date] = _class, 1, BLANK())

 Next I created a measure to count the logins cumulatively (dark blue line)

running sum = CALCULATE( 
 SUM('Log'[First Login]), 
 FILTER(ALLSELECTED('Log'), 
 'Log'[Date] >= DATE(YEAR(MAX('Log'[Date])),1,1) &&
 'Log'[Date] <= MAX('Log'[date])
 ))

[mickey64]

How about use a measure below?

    UserNum = DISTINCTCOUNT(Log Table[UserID])

    X-axis:Date

    Y-axis:UserNum