Hello and a greeting to everyone, I am new to the forum and I do not know if this goes in the right section. For the last few months I've been researching how Power Bi works and getting a little bit into DAX.
On a website where there is a powerbi course, I find this expression that I have applied to a table for the calculation of the kilometers made the previous week:
Kms. Anterio week ? calculate([kmmeters],filter('Main table'),countrows(filter('Main table',earlier('Main table'[DATE])-dateadd(calendar[Date],-7,DAY)))))
The fact is that the expression works (as long as there are kilometers made daily), but I do not understand the following, no matter how many laps I give it:
- I know how the earlier expression works and what it returns, in this case it would return the rows a week before to the updated row.
- Countrows returns the number of rows that meet that condition, so as far as my knowledge reaches, it returns a scalar.
- Now it arrives, the part I don't have,
filter(all('Tabla principal'),countrows(filter('T.......................
Here I guess that in the filter, I select the entire table without any filter applied to it, but the second argument of filter is the countrows that returns a scalar ( a number ) and in theory the second argument of filter is a condition, a Boolean expression. if I do a direct filter and in the second argument I place a number, power bi gives me error, but if I do it with filter(all( 'Main table'), countrows...........) if I support it.
Would anyone know where I commit the failure to analyze it?
Thank you in advance and a greeting.
