Help calculating simpson's diversity index

Hi vemee ，

Here some steps that I want to share, you can check them if they suitable for your requirement.

Here is my test data:

Create a calculate column

Simpson's Diversity Index = 
VAR Total_Observations = COUNTROWS('Table')
VAR Value_Occurrences = 
    CALCULATE(
        COUNTROWS('Table'),
         FILTER('Table',
          'Table'[Colors] = EARLIER('Table'[Colors])
        )
    )
RETURN
1 -  SUMX('Table',Value_Occurrences * (Value_Occurrences-1)) / (Total_Observations * (Total_Observations - 1))

Final output

Best regards,

Albert He

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