Power BI: Calculating average of a column's current row divided by the first

Question

Please see the file I have shared in the following link:

https://drive.google.com/file/d/1q7FE85qHoB_OhAm4hlmFidh6WP3m-UnK/view?usp=sharing

I have a dataset with the value of various items on different dates. I first need to calculate ratio by dividing the value of an item on a particular date with the earliest value in the chosen date filters. I then need to show the per day ratio of all items (columns I & J) as the desired output.

I am able to get the "first value" in the filtered table by using the following formula:

first_cr = 
VAR item = MAX('Table 1'[item])
VAR min_updated = CALCULATE(
    MIN('Table 1'[last_updated]),
    'Table 1'[item] = item,
    ALLSELECTED('Table 1')
)
RETURN
CALCULATE(
    AVERAGE('Table 1'[cr]),
    'Table 1'[last_updated] = min_updated,
    'Table 1'[item] = item,
    ALLSELECTED('Table 1'[fk])
)

However, I am unable to figure out how to calculate the average of all the individual item ratios at just the date level. I guess I need to use AVERAGEX somehow, but not sure how. Perhaps my first_cr formula could use more refinement.

I'd appreciate any help or guidance in the right direction. Thanks for your time.

Shahid Thaika Shahid Thaika · Accepted Answer · 2019-11-05T13:07:05

I was able to get the answer using the following formula. If anyone can refine it better, please do so, else I'll accept my answer after a few days.

ret = 
var lastUpdated = MAX(Sheet1[Date])
var tbl = ALLSELECTED(Sheet1)
RETURN 
CALCULATE(
    AVERAGEX(
        Sheet1,
        var i = Sheet1[Item]
        var minUpdated = CALCULATE(
            MIN(Sheet1[Date]),
            Sheet1[Item] = i,
            tbl
        )
        var first_cr = CALCULATE(
            AVERAGE(Sheet1[Return]),
            Sheet1[Date] = minUpdated,
            Sheet1[Item] = i,
            tbl
        )

        RETURN Sheet1[Return] / first_cr
    ),
    Sheet1[Date] = lastUpdated,
    tbl
)

Power BI: Calculating average of a column's current row divided by the first

1 Answers