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Compare Previous Two Rows with a Current Row using DAX
Hi Everyone, I have to create a new column and am trying to compare rows in a single column when a particular value exists in any of the rows. For e.g. If Table[category] = "Site Down", then ...
There are newer DAX functions that are similar to SQL's LAG. For example, OFFSET:
IsSiteDown = VAR Summary = SUMMARIZE ( Table2, Table2[sitename], Table2[category], Table2[firstoccurrence] ) VAR Prev1Cat = MAXX ( OFFSET ( -1, Summary, ORDERBY ( Table2[firstoccurrence] ), PARTITIONBY ( Table2[sitename] ) ), Table2[category] ) VAR Prev2Cat = MAXX ( OFFSET ( -2, Summary, ORDERBY ( Table2[firstoccurrence] ), PARTITIONBY ( Table2[sitename] ) ), Table2[category] ) VAR Result = IF ( Table2[category] = "Site Down" && Prev1Cat = "Low Voltage" && Prev2Cat = "AC Mains Failure", "Yes", "No" ) RETURN Result
hi ahsan005
you would need to
1) add an index column in Power Query
https://learn.microsoft.com/en-us/power-query/add-index-column
2) add a new column with DAX like this:
Tag =
VAR _site = [sitename]
VAR _index = [index]
VAR _table =
FILTER(data, [sitename]= _site)
VAR _lastcategory =
MINX(
FILTER( _table, [Index] =_index -1
),
[category]
)
VAR _llastcategory =
MINX(
FILTER( _table, [Index] =_index -2
),
[category]
)
RETURN
IF(
[category]="Site Down"
&&_lastcategory="Low Voltage"
&&_llastcategory="AC Mains Failure",
"Yes", "No"
)
i tried and it worked like this:
Two additional comments:
1) Power BI is efficient handling columns but not that good handling rows.
2) EARLIER is to get the row context in the earlier set of iteration, not the context of the earlier row or the earlier iteration scanning in the current set of iteration.
