Delta Between Rows for Multiple Column in a Matrix

[JimKingPowerBI]

Thanks in advance for any assistance you may provide.

I have a matrix in which I would like to calculate the difference (Delta) between rows in the matrix, by column.

Data

As Of Date	Error Type	Date Index
07/30/2019	Error Type 1	1
07/30/2019	Error Type 1	1
07/30/2019	Error Type 1	1
07/30/2019	Error Type 2	1
07/30/2019	Error Type 2	1
07/31/2019	Error Type 1	2
07/31/2019	Error Type 1	2
07/31/2019	Error Type 1	2
07/31/2019	Error Type 1	2
07/31/2019	Error Type 1	2
07/31/2019	Error Type 2	2
07/31/2019	Error Type 2	2
07/31/2019	Error Type 2	2
07/31/2019	Error Type 2	2
07/31/2019	Error Type 2	2
07/31/2019	Error Type 2	2
07/31/2019	Error Type 2	2
07/31/2019	Error Type 2	2
07/31/2019	Error Type 2	2
08/01/2019	Error Type 1	3
08/01/2019	Error Type 1	3
08/01/2019	Error Type 1	3
08/01/2019	Error Type 1	3
08/01/2019	Error Type 1	3
08/01/2019	Error Type 1	3
08/01/2019	Error Type 2	3
08/05/2019	Error Type 1	4
08/05/2019	Error Type 1	4
08/05/2019	Error Type 2	4
08/05/2019	Error Type 2	4
08/05/2019	Error Type 2	4
08/05/2019	Error Type 2	4
08/05/2019	Error Type 2	4
08/05/2019	Error Type 2	4

The data has several "Error Types" for each "As Of Date".

I created the Date Index column on the table for reference purposes in the Delta measure.

Date Index = RANKX('Data Errors' , 'Data Errors'[As Of Date] ,, ASC , Dense)

I created a Delta measure, but I don't know how to dynamically reference each Error Type. Note the hard refrence to "Error Type 1" (highlighted in red).

Delta = 
VAR PRIOR_COUNT = 
    VAR CURRENT_RANK = SELECTEDVALUE('Data Errors'[Date Index])
    RETURN 
        CALCULATE(COUNTROWS('Data Errors'),
            FILTER(
                FILTER(ALL('Data Errors'),'Data Errors'[Date Index]=CURRENT_RANK-1),
            'Data Errors'[Error Type]="Error Type 1"))
RETURN 
    COUNTROWS('Data Errors') - PRIOR_COUNT

Matrix (The second matrix to the right is to show the totals without a total for the Delta column.)

The Delta column is correct for only the Error Type 1 column, because that is hardcoded into the measure.

Can, and will, someone please help me dynamically reference the Error Type in my measure so I can have a delta column for each Error Type in my table?

[MFelix · Accepted solution]

Hi @JimKingPowerBI ,

To what I can understand from you question you want to have the result of the difference from one day to the other, believe that you don't need to have a rankx columns, try the following code:

Delta without RANK = 
VAR PRIOR_COUNT =
    CALCULATE (
        COUNTROWS ( 'Data Errors' );
        FILTER (
            ALL ( 'Data Errors'[As Of Date] );
            'Data Errors'[As Of Date]
                = MAXX (
                    FILTER (
                        ALL ( 'Data Errors'[As Of Date] );
                        'Data Errors'[As Of Date] < MAX ( 'Data Errors'[As Of Date] )
                    );
                    'Data Errors'[As Of Date]
                )
        )
    )
RETURN
    COUNTROWS ( 'Data Errors' ) - PRIOR_COUNT

When you add the error type on the columns this will give context to your measure.

Using the measure you have you need to redo it to:

Delta = 
VAR PRIOR_COUNT = 
    VAR CURRENT_RANK = SELECTEDVALUE('Data Errors'[Date Index])
    RETURN 
        CALCULATE(COUNTROWS('Data Errors');
            FILTER(
                FILTER(ALL('Data Errors');'Data Errors'[Date Index]  = CURRENT_RANK-1);
            'Data Errors'[Error Type]=SELECTEDVALUE('Data Errors'[Error Type])))
RETURN 
    COUNTROWS('Data Errors') - PRIOR_COUNT

The highleted part is the one that you had hardcoded.

As you can see both results are the same.

Regards,

MFelix

[JimKingPowerBI]

Hi @MFelix ,

Thanks so much. You're brilliant!! It worked perfectly... once I replaced your semicolons with commas.