Lookup value based on group max value in PowerBI - powerbi

Question

I would like to first state that I am a beginner with DAX and this is one of my attempts (which seemed to be the closest to the solution I need). I come from a SQL heavy background so my "thinking" is somehow fixed in that way.
I have tried to solve this by implementing something that would match the following SQL logic:
CASE WHEN MAX(column) OVER (PARTITION BY group) = column2 THEN column3 ELSE "" END
However, this doesn't seem to work directly like in SQL, so I would like to ask for some help.
I have the current set of data, which is imported from a simple text file.
ID GroupID Amount
1 2 8502
2 2 8502
3 2 8502
4 2 8502
1 6 80
2 6 80
And I would like to find a way to get the following result:
ID GroupID Amount LatestGroupAmount
1 2 8502
2 2 8502
3 2 8502
4 2 8502 8502
1 6 80
2 6 80 80
And then have a Total under LatestGroupAmount, totaling to 8582.
So far, I have created 2 new measures in my table, MaxID and MaxIDbyGroup.
MaxID = MAX(data[ID])
and
MaxIDbyGroup = CALCULATE([MaxID], ALLEXCEPT(data, data[GroupID]))
This gives me:
ID GroupID Amount MaxID MaxIDbyGroup
1 2 8502 1 4
2 2 8502 2 4
3 2 8502 3 4
4 2 8502 4 4
1 6 80 1 2
2 6 80 2 2
Now, I would like to create a new measure that just does a lookup of the Amount, based on the equality between ID and MaxIDbyGroup.
I have tried to create a new measure with the following definition:
LatestGroupAmount = LOOKUPVALUE(data[Amount], data[GroupId], data[MaxIDbyGroup])
But this gives me the following output:
ID GroupID Amount LatestGroupAmount
1 2 8502
2 2 8502
3 2 8502
4 2 8502
1 6 80 8502
2 6 80 8502
Edit:
I have created another measure:
MaxGrid = MAX(data[GroupID])
And I have tried using CALCULATE with the following definition for LatestGroupAmount:
LatestGroupAmount = CALCULATE(
SUM( data[Amount] ),
FILTER( data, data[ID] = data[MAXID_by_author]), FILTER(data, data[GroupID] = data[MaxGrid]) )
And it seems to show what I want, however, it filters the 6 rows I have to only 2 rows (although I think it does an aggregation).
ID GroupID Amount LatestGroupAmount
4 2 8502 8502
2 6 80 80
The reason I say I think it's an aggregation, is because I add the MaxID to the widget, the output shows the correct number of rows. Essentially, the image below is the output that I want, except for the MaxID column.
If I remove the MaxID column, the widget automatically summarizes to two rows, but I want to show all of the 6 rows.

Answer 1

You can use this measure to achieve your result:
LatestGroupAmount =
VAR TT01 = ADDCOLUMNS(
SUMMARIZE(Data,Data[ID],Data[GroupID]),
"MaxID",CALCULATE(MAX(Data[ID]),ALLEXCEPT(Data,Data[GroupID]))
)
RETURN
CALCULATE(MAX(Data[Amount]),
FILTER(TT01,
Data[ID] =[MaxID]))
Then define your visual table by putting [ID], [GroupID],[Amount] on rows, and above measure into values, Then:
Please Make sure that For [ID] and [GroupID Columns], show items with no data is ticked or checked, like in the picture below.

Answer 2

Your current definition for LatestGroupAmount is searching in the GroupId column, though I believe that should be the ID column, i.e.:
LOOKUPVALUE( data[Amount], data[ID], data[MaxIDbyGroup] )
In any case, this will fail since that column contains duplicate entries. As such, you should use something like:
LatestGroupAmount :=
CALCULATE(
MAX( data[Amount] ),
FILTER( data, data[Id] = data[MaxIDbyGroup] )
)