DAX YTD Different end dates per channel - data dates consistency problem

MarkCBB

Yes, your assumption is correct. Within the PYTD DAX formula, the variable ChannelLastDateGlobal is the last date which appears in FACT for a given Channel, so may not be a month-end date.

You might want to use more sophisticated logic to handle cases where a particular month has passed but the last transaction date in that month was not the last day of the month. For example, for Channel TOPS, if the last transaction date were 29 May, PYTD would be cut-off at 29 May, whereas 31 May would make sense given we know May has completely passed. One way of doing this might be to 'round up' ChannelLastDateGlobal to the end of the month if any Channel has dates from later months.

nickchobotar

Yes, ALLEXCEPT can be used with an entire related table as the 2nd argument, instead of a column of a the expanded table from the 1st argument.

In this case, ALLEXCEPT ( 'FACT', 'CHANNEL' ) clears all filters on any columns of 'CHANNEL' from the expanded 'FACT' table (i.e. 'FACT' left-outer-join all related tables in this model). You could use ALLEXCEPT ( 'FACT', CHANNEL[CHANNEL] ) in this case since we were only filtering on the CHANNEL column anyway. The intention here is to get the global max date for a Channel by clearing all filters on the 'FACT' table except Channel.

I don't think ALLEXCEPT ( CHANNEL, CHANNEL[CHANNEL] ) would have the desired effect, since we want to ensure we get a global max date for a given Channel, so we want to clear any non-Channel filters that would filter 'FACT' (such as 'CALENDAR' ). Clearing filters on CHANNEL is not sufficient.

Cheers,

Owen :)

Thank you OwenAuger

This looks great - very clever. (I am really keen to see how you would have used TREATAS when the bug is fixed, I have never heard of that function before. I read the pop-up and seems like a very helpful function to know)

I am doing some manual checks and I found something that does not make sense to me, but this could just be my understanding:

If I manually sum the totals for each channel for the same consistency months for the previous year as the current year I get a different value.

Below I get 958,523, However, if I drop the PYTD Measure into a card visual I get 944,797).

Could you explain this to me? (My only assumption is that the table below for the items in yellow are the SUM for all the dates within the Month whereas the current year's Month might not end on the end date, of the month thus pushing back the PYTD to that specific date within the corresponding month - If this assumption is correct then this is exactly what I am looking for, if not could you explain to me how it is working?

Hi OwenAuger

I noticed in your gobal date variable, you use just the tables as arguments for ALLEXCEPT (   ALLEXPECT (<table>, <column> [, <column>[,…]])

 

ALLEXCEPT ( 'FACT', 'CHANNEL' )

I did not even know it was possible. That's pretty cool!  Any specific reason behind that?

I am only asking because using CHANNEL tbl and column probably it will also work.
ALLEXCEPT (CHANNEL, CHANNEL[CHANNEL] ) 

nickchobotar I got an error on that piece I had to update it to this:

ALLEXCEPT (CHANNEL, CHANNEL[CHANNEL] ) 

Thank you for the feedback OwenAuger - That is what I was hoping it would do.

You are correct, I had to change the ALLEXCEPT ( CHANNEL, CHANNEL[CHANNEL] )  back to the way you had it.

With regards to the advice you gave 

"You might want to use more sophisticated logic to handle cases where a particular month has passed but the last transaction date in that month was not the last day of the month. For example, for Channel TOPS, if the last transaction date were 29 May, PYTD would be cut-off at 29 May, whereas 31 May would make sense given we know May has completely passed. One way of doing this might be to 'round up' ChannelLastDateGlobal to the end of the month if any Channel has dates from later months."

Thankfully this will not happen within this dataset as there is more than likely more sales that occur on the last date of the month. but out of interest how would you do this? I am a newbie so enjoying and appreciating the teachings you are providing. 

Based on the Function you provide I have created the following which after some manual checks all seems to be working.

• TYTM - This Year This Month
• TYPM - This Year Previous Month
• PYTM - Previous Year This Month
• TYTQ - This Year This Quater
• TYPQ - This Year Previous Quater
• PYTQ - Previous Year this Quater

Below are the functions:

TYTM UNITS = 
SUMX (
	VALUES ( MASTER_SITE[CHANNEL] ),
	VAR CalendarLastDateSelected = 
		MAX ( 'CALENDAR'[DATE] )
	VAR ChannelLastDateGlobal =
		CALCULATE (	MAX ( 'FACT'[DATE] ), ALLEXCEPT ( 'FACT', MASTER_SITE[CHANNEL] ) )
	VAR ChannelLastDateApplied =
		MIN ( CalendarLastDateSelected, ChannelLastDateGlobal )
	RETURN 
		CALCULATE ( 
			CALCULATE([TOTAL UNITS],DATESMTD('CALENDAR'[DATE])),
			DATESMTD('CALENDAR'[DATE] = ChannelLastDateApplied)
		)
)

TYPM UNITS = 
SUMX (
	VALUES ( MASTER_SITE[CHANNEL] ),
	VAR CalendarLastDateSelected = 
		MAX ( 'CALENDAR'[DATE] )
	VAR ChannelLastDateGlobal =
		CALCULATE (	MAX ( 'FACT'[DATE] ), ALLEXCEPT ( 'FACT', MASTER_SITE[CHANNEL] ,'CALENDAR'[Month Year]) )
	VAR ChannelLastDateApplied =
		MIN ( CalendarLastDateSelected, ChannelLastDateGlobal ) 
	RETURN 
		CALCULATE ( 
			CALCULATE([TOTAL UNITS],DATESMTD('CALENDAR'[DATE])) ,
			PREVIOUSMONTH('CALENDAR'[DATE].[Date] = ChannelLastDateApplied)
		)
)

PYTM UNITS = 
SUMX (
	VALUES ( MASTER_SITE[CHANNEL] ),
	VAR CalendarLastDateSelected = 
		MAX ( 'CALENDAR'[DATE] )
	VAR ChannelLastDateGlobal =
		CALCULATE (	MAX ( 'FACT'[DATE] ), ALLEXCEPT ( 'FACT', MASTER_SITE[CHANNEL] ) )
	VAR ChannelLastDateApplied =
		MIN ( CalendarLastDateSelected, ChannelLastDateGlobal ) 
	RETURN 
		CALCULATE ( 
			CALCULATE([TOTAL UNITS],DATESMTD(DATEADD('CALENDAR'[DATE],-1,YEAR))),
			DATESMTD('CALENDAR'[DATE] = ChannelLastDateApplied)
		)
)

TYTQ UNITS = 
SUMX (
	VALUES ( MASTER_SITE[CHANNEL] ),
	VAR CalendarLastDateSelected = 
		MAX ( 'CALENDAR'[DATE] )
	VAR ChannelLastDateGlobal =
		CALCULATE (	MAX ( 'FACT'[DATE] ), ALLEXCEPT ( 'FACT', MASTER_SITE[CHANNEL] ) )
	VAR ChannelLastDateApplied =
		MIN ( CalendarLastDateSelected, ChannelLastDateGlobal ) 
	RETURN 
		CALCULATE ( 
			CALCULATE([TOTAL UNITS],DATESQTD('CALENDAR'[DATE])),
			DATESQTD('CALENDAR'[DATE] = ChannelLastDateApplied)
		)
)

TYPQ UNITS = 
SUMX (
	VALUES ( MASTER_SITE[CHANNEL] ),
	VAR CalendarLastDateSelected = 
		MAX ( 'CALENDAR'[DATE] )
	VAR ChannelLastDateGlobal =
		CALCULATE (	MAX ( 'FACT'[DATE] ), ALLEXCEPT ( 'FACT', MASTER_SITE[CHANNEL]))
	VAR ChannelLastDateApplied =
		MIN ( CalendarLastDateSelected, ChannelLastDateGlobal )
	RETURN 
		CALCULATE ( 
			CALCULATE([TOTAL UNITS],DATESQTD('CALENDAR'[DATE])) ,
			PREVIOUSQUARTER('CALENDAR'[DATE].[Date] = ChannelLastDateApplied)
		)
)

PYTQ UNITS = 
SUMX (
	VALUES ( MASTER_SITE[CHANNEL] ),
	VAR CalendarLastDateSelected = 
		MAX ( 'CALENDAR'[DATE] )
	VAR ChannelLastDateGlobal =
		CALCULATE (	MAX ( 'FACT'[DATE] ), ALLEXCEPT ( 'FACT', MASTER_SITE[CHANNEL] ) )
	VAR ChannelLastDateApplied =
		MIN ( CalendarLastDateSelected, ChannelLastDateGlobal )
	RETURN 
		CALCULATE ( 
			CALCULATE([TOTAL UNITS],DATESQTD(DATEADD('CALENDAR'[DATE],-1,YEAR))),
			DATESQTD('CALENDAR'[DATE] = ChannelLastDateApplied)
		)
)

Out of interest, I have noticed that If I add a Column Chart Visual with Year-Month as the axis and Total Units as the value, and I select a previous Month, some of the above measures show as (Blank), I assume that this is due to the context of the dates changing the measure? If I wanted to update the function so that if I clicked on one of the Previous months, the function then thinks that that month is the latest month in the data so the user could in effect roll back the report up until that month. So If the latest month of all the data was July and the user clicked on the June Month column in that chart, the functions would update as if there was no July data yet. Could the above functions be edited in such a way to achieve this?

Looking forward to your response. 

Regards,

Mark B

CLIP

above is a clip of how it is interacting (Note the values will be different as the data is the full dataset)

in the clip, you will see what happens when One month is selected, and near the end of the clip, you will see how I would like it to work (When I select all months up until the 2nd last month.

so Instead of filtering to the month, it should filter up-until the month. Hope that makes sense?

MarkCBB

Apologies for late reply.

On your first question about handling cases where the last transaction wasn't on an end-of-month date, I was thinking of something like this:

1. Find the last date in the FACT table across all Channels (with all filters removed), and call this date OverallLastDateGlobal
2. Increase ChannelLastDateGlobal up to OverallLastDateGlobal, but don't go beyond the end of the month. Call this date ChannelLastDateGlobalModified.

This would mean, for example:

• If  Channel A had transactions up to 28 May, but Channel B had transactions up to 31 July, Channel A's last date would be treated as 31 May. Channel B's transactions indicate that May must be complete, and Channel A just happened to have no transactions from 29 May to 31 May.
• If Channel A had transactions up to 14 May, but Channel B had transactions up to 28 May, Channel A's last date would be treated as 28 May. Channel B's transactions indicate that time has passed up to 28 May, and Channel A just happened to have no transactions after 14 May.

The code would look like:

PYTD UNITS = 
SUMX (
    VALUES ( CHANNEL[CHANNEL] ),
    // Iterate over  CHANNELs
    VAR CalendarLastDateSelected = 
        MAX ( 'CALENDAR'[DATE] )
        // Last date selected on CALENDAR table
    VAR ChannelLastDateGlobal =
        CALCULATE ( MAX ( 'FACT'[DATE] ), ALLEXCEPT ( 'FACT', 'CHANNEL' ) )
        // Last date that exists in FACT for the current CHANNEL (ignoring any filters other than CHANNEL)
    VAR OverallLastDateGlobal =
        CALCULATE ( MAX ( 'FACT'[DATE] ), ALL ( 'FACT' ) )
    VAR ChannelLastDateGlobalModified =
        MAX ( ChannelLastDateGlobal, MIN ( OverallLastDateGlobal, EOMONTH ( ChannelLastDateGlobal, 0 ) ) )
    VAR ChannelLastDateApplied =
        MIN ( CalendarLastDateSelected, ChannelLastDateGlobalModified )
        // The earlier of these is the date to apply for PYTD calculation  
    RETURN 
        CALCULATE ( 
            [TYTD UNITS],
            SAMEPERIODLASTYEAR( 'CALENDAR'[DATE] = ChannelLastDateApplied )
        )
)

I will have to get back to you on your "previous month" query, unless someone else tackles it in the mean time :)

Cheers,

Owen