Filtering data already filtered using DAX

Question

Hi there
I am using DAX to calculate the count of instances in a filtered table
e.g.
=CALCULATE( COUNT(Table[Tariff] ,
FILTER( Table , Table[Tariff] > 0 )
This part of the code works fine. My trouble arises when I am trying to filter the table that I have already filtered:
=CALCULATE( COUNT(Table[Tariff] ,
FILTER ( FILTER( Table , Table[Tariff] > 0 ) , Table[Tariff] = MIN(Table[Tariff]) )
In the above calculation, I want to 
1. Filter out the tariffs that are greater than zero [this bit works fine]; and then
2. Take that table filtered from 1. above and further filter that by extracting only those tariffs that are equal to the minimum in that data table [this part isn't working].
Instead of doing what I need it to, this formula is treating the outer FILTER in the same manner that it would be treated if I had only one filter. Thus, as zero is the minimum in the unfiltered data set it is only returning all the zero tariffs - even through
I filtered these out already.
If anyone can please assist, it would be much appreciated.
Cheers
Andrew

Answer 1

Hi Andrew,
Something along these line may work...
=CALCULATE(
SUM(TariffData[Tariff])/COUNT(TariffData[Tariff]),
FILTER(
FILTER(
TariffData,
TariffData[BEGIN_DATE_INDEX] <= [Date_Count]
&& TariffData[END_DATE_INDEX] >= [Date_Count]
TariffData[Tariff_Duration] = CALCULATE(
MIN(TariffData[Tariff_Duration]),
FILTER(
TariffData,
TariffData[BEGIN_DATE_INDEX] <= [Date_Count]
&& TariffData[END_DATE_INDEX] >= [Date_Count]
...But it's likely that you'll need to adjust the inner most CALCULATE to get the right behaviour due to the filter context transition. If you're able to provide some test data and details of how the data has been modelled, we should be able to arrive at
a solution that definitely works.
Regards,
Michael Amadi
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