Line chart with Legend and additional measure

RafalMonka not sure about the custom visual but you are on right track, maybe not to add a virtual user in your main user table but create a disconnect user table, add a virtual user in that one and then use that in the visuals, ofcourse it will require to write a new measure to use the disconnected user table.

aj1973, in that case, he has to create measure for every single assigned to user name and not sure it is a scalable solution. Just my 2 cents.

parry2k's suggestion should work. Create a new table to use for the legend

Legend = UNION ( VALUES ( Table1[User] ), { "Average" } )

Then define a measure to use in the line chart. (Edited to include KEEPFILTERS.)

ChartValue = 
IF (
    SELECTEDVALUE ( Legend[User] ) = "Average",
    AVERAGEX ( VALUES ( Table1[User] ), CALCULATE ( SUM ( Table1[Value] ) ) ),
    CALCULATE (
        SUM ( Table1[Value] ),
        KEEPFILTERS ( TREATAS ( VALUES ( Legend[User] ), Table1[User] ) )
    )
)

Result:

See attached .pbix.

You may want to vote for this Idea:
Line Chart with multiple values fields and legends

Hi RafalMonka 

Have you tried adding an Average line here

Yes, we have. But we have only obtained straight line (average for the whole period).

Average line is based on the measure used in Values field.

We need average per certain months, as we have shown on the previous screen.

Hi Alexis,

many thanks for code, but take into account that Legend table should have relationship with Table1.

The reason is that we have multiple filters on dashboard, for instance to limit list of users to certain projects, teams.

So we cannot display all the users from Legend table on a chart.

RafalMonka Don't you have another filter directly filter the table1, if those are then the solution provided by AlexisOlson should work, let's say you have a table1 filter on a project and only two users are associated with that project, in the solution, it will show only two users, not other users. Seems like you need to tweak your data model if this is not working as expected but the solution provided AlexisOlson is the way to go.

RafalMonka I see, change the measure to this:

ChartValue = 
VAR __users = INTERSECT ( VALUES ( Legend[User] ), VALUES ( Table1[User] ) )
RETURN
IF (
    SELECTEDVALUE ( Legend[User] ) = "Average",
    AVERAGEX ( VALUES ( Table1[User] ), CALCULATE ( SUM ( Table1[Value] ) ) ),
    CALCULATE (
        SUM ( Table1[Value] ),
        TREATAS ( __users, Table1[User] )
        // TREATAS ( VALUES ( Legend[User] ), Table1[User] )
    )
)

AlexisOlson Unfortunately that will not work, FYI