RANKX Returns the ranking of a number in a list of numbers for each row in the table argument.
Syntax
RANKX(table, expression[, value[, order[, ties]]])
Parameters
table – Any DAX expression that returns a table of data over which the expression is evaluated.
expression – Any DAX expression that returns a single scalar value. The expression is evaluated for each row of table, to generate all possible values for ranking. See the remarks section to understand the function behavior when expression evaluates to BLANK.
value – (Optional) Any DAX expression that returns a single scalar value whose rank is to be found. See the remarks section to understand the function’s behavior when value is not found in the expression.
When the value parameter is omitted, the value of expression at the current row is used instead.
order (Optional) A value that specifies how to rank value, low to high or high to low:
0 FALSE – Ranks in descending order of values of expression. If value is equal to the highest number in expression then RANKX returns 1.
This is the default value when order parameter is omitted.
1 TRUE – Ranks in ascending order of expression. If value is equal to the lowest number in expression then RANKX returns 1.
ties
(Optional) An enumeration that defines how to determine ranking when there are ties.
Skip – The next rank value, after a tie, is the rank value of the tie plus the count of tied values. For example if five (5) values are tied with a rank of 11 then the next value will receive a rank of 16 (11 + 5).
This is the default value when ties parameter is omitted.
Dense – The next rank value, after a tie, is the next rank value. For example if five (5) values are tied with a rank of 11 then the next value will receive a rank of 12.
Return Value
The rank number of value among all possible values of expression evaluated for all rows of table numbers.
Reference Data
https://docs.microsoft.com/en-us/dax/dax-function-reference