Changing the filter context on iterations of CONCATENATEX

[rlannvercorp]

I have table of the following values:

Category1,Category2

A,1

A,2

A,3

A,4

B,1

B,3

B,4

C,2

C,4

I want a measure to return a string summarizing this table as such (order of values not important):

A (1, 2, 3, 4),
B (1, 3),

C (2, 4)

But all I've been able to come up with is 

Nested List of Values =

var category2list = CONCATENATEX(DISTINCT('Table'[Category2]), 'Table'[Category2], ", ")

return

CONCATENATEX( DISTINCT('Table'[Category1]),

'Table'[Category1] & " (" & category2list & ")", ", " & UNICHAR(10))

Which returns

A (1, 2, 3, 4),

B (1, 2, 3, 4),

C (1, 2, 3, 4) so the inner expression isn't being run on a table filtered for each iteration of the outer concatenatex.

I would also like to be able to use a filter on either category to return a filtered list like so:

Select Category2 = 4 returns

A (4),
C (4) 

or Category2 = 2 or 3 returns

A (2, 3),

B (3),

C (2)

[CNENFRNL]

an alternative solution,

ConcX = 
CONCATENATEX(
    DISTINCT( 'text'[Category1] ),
    'text'[Category1] & ": "
        & CALCULATE( CONCATENATEX( DISTINCT( 'text'[Category2] ), 'text'[Category2], ", " ) ),
    UNICHAR( 10 )
)

[amitchandak]

@rlannvercorp ,

Try to get more than one row like

Nested List of Values =

var category2list = CONCATENATEX(DISTINCT('Table'[Category2]), 'Table'[Category2], ", ")

return

'Table'[Category1] & " (" & category2list & ")"

or

Nested List of Values =

var category2list = CONCATENATEX('Table', 'Table'[Category2], ", ")

return

'Table'[Category1] & " (" & category2list & ")"

[amitchandak · Accepted solution]

@rlannvercorp ,

Try like

Measure = var _tab = SUMMARIZE('text' , 'text'[Category1], "_1", CONCATENATEX(DISTINCT('text'[Category2]), 'text'[Category2],",")) return CONCATENATEX( _tab,
[Category1] & " (" & [_1]& ")", ", " & UNICHAR(10))

[rlannvercorp]

@amitchandak  Now I understand.  Very elegant and simple.  Thanks for the help.

[rlannvercorp]

Thank you!  Now to figure out HOW it works.

[rlannvercorp]

DAX doesn't accept 'Table'[Category1] in the last line.  It's requiring a scalar value.