Need measure to calculate if last year's week number equals this year's week number

[jdwalker5]

Hello,

Just learning how to use custom DAX code to create measures in Power BI.  I'm trying to create a simple table visual using measures that calcualte and compare this year's results to last year's where the week numbers match.  My data already has a week number column that corresponds with my company's fiscal year so I do not need to use a date column.  Creating the measures for this year were easy because the data is limited to the current week.  In other words, the data source doesn't contain any data for dates beyond the current week that we're in now.  So for 2020 data, I created a measure for max week and called it current week.  Now I need to create a measure to pull last year's data for that same week number so that I can compare results year over year.  I cannot use max for last year's data because it has all 53 weeks.

This is basically how I would like to present the data:

YoY Comparision	Week 40 This Year	Week 40 Last Year
Products Sold	100	85

Again, my data has a week number column.  I just need to find a way to get last year's data for the same week as this year's current week.  Any help is very much appreciated!

[jdwalker5]

This worked perfectly!  Thanks for the solution.  I actually used this for a separate measure to pull the week prior to max.  What was odd is I had to use MAX (data[Week]) - 10 to accomplish that.  Logically I would expect to be able to use MAX(data[week]) -1 but it continued to show data from the max week.  My week column is data time whole number so I couldn't figure out why -10 worked but I'll take what I can get.  Thanks again for your help!

[Nathaniel_C]

Hi @jdwalker5 ,
You are very welcome!

Thank you,

Nathaniel

[Nathaniel_C · Accepted solution]

Hi @jdwalker5 ,
If this solves your issue, please mark it so others can find it more easily!

Thank you,

Nathaniel

[Nathaniel_C]

Hi @jdwalker5 ,

So does your data have a year column?

Here is a quick table to show proof of concept.

The measure 

Last Year Product Same Week =
VAR PastYear =
    MAX ( Data[Year] ) - 1
VAR CurrentWeek =
    MAX ( Data[Week] )
VAR _calc =
    CALCULATE (
        MAX ( Data[ProductSold] ),
        Data[Year] = PastYear,
        Data[Week] = CurrentWeek
    )
RETURN
    _calc

The result

Let me know if you have any questions.

If this solves your issues, please mark it as the solution, so that others can find it easily. Kudos 👍are nice too.
Nathaniel