--  RANKX computes the ranking of an expression over a table
--  The expression is evaluated during the iteration over the
--  table and then in the evaluation context of RANKX.
--  The result is the position of the outer evaluation in the 
--  lookup table built during the iteration
DEFINE
    VAR BrandsAndSales =
        ADDCOLUMNS (
            VALUES ( 'Product'[Brand] ),
            "@Amt", [Sales Amount]
        )
EVALUATE
ADDCOLUMNS (
    BrandsAndSales,
    "Rank",
        RANKX (
            BrandsAndSales,
            [@Amt]
        )
)
ORDER BY [@Amt] DESC

--  The third argument of RANKX is useful when the outer 
--  evaluation requires a different expression than the
--  inner one. For example, when ranking an expression over
--  a pre-built lookup table
DEFINE
    VAR SalesLevels =
        SELECTCOLUMNS ( { 6000000, 3000000, 1500000, 750000, 0 }, "@Limit", [Value] )

EVALUATE
ADDCOLUMNS (
    VALUES ( Product[Brand] ),
    "Sales Amount", [Sales Amount],
    "Level", RANKX ( SalesLevels, [@Limit], [Sales Amount] )
)
ORDER BY [Level] ASC

--  The fourth argument of RANKX specifies the order of ranking
--  it can be DESC (default) or ASC
DEFINE
    VAR BrandsAndSales =
        ADDCOLUMNS ( VALUES ( 'Product'[Brand] ), "@Amt", [Sales Amount] )
EVALUATE
ADDCOLUMNS (
    BrandsAndSales,
    "Rank ASC",  RANKX ( BrandsAndSales, [@Amt], [@Amt], ASC ),
    "Rank DESC", RANKX ( BrandsAndSales, [@Amt], [@Amt], DESC ),
    "Rank (default)", RANKX ( BrandsAndSales, [@Amt], [@Amt] )
)
ORDER BY [@Amt] DESC

--  The fifth argument of RANKX specifies the behavior in
--  case of ties. SKIP (default) skips positions, whereas
--  DENSE guarantees a 1-step increment in the ranking
DEFINE
    VAR BrandsAndSales =
        ADDCOLUMNS (
            VALUES ( 'Product'[Brand] ),
            "@Amt", MROUND ( [Sales Amount], 1E6 )
        )
EVALUATE
ADDCOLUMNS (
    BrandsAndSales,
    "Rank SKIP",  RANKX ( BrandsAndSales, [@Amt], [@Amt], DESC, SKIP ),
    "Rank DENSE", RANKX ( BrandsAndSales, [@Amt], [@Amt], DESC, DENSE )
)
ORDER BY [@Amt] DESC