Find previous date for given value

Hey tlong 

use this DAX statement to create a calculated column:

Column = 
var _group = 'Table'[Value]
var _date = 'Table'[Date]
return
CALCULATE(
    MAX('Table'[Date])
    , FILTER(
        ALL('Table')  
        , 'Table'[Date] < _date && 'Table'[Value] = _group
    )
)

The result will look like this:

Please be aware that depending of number of rows in your dataset can become incredibly slow, this is simply because the formula and storage engine do not support windowing operations like this.

Hopefully this is what you are looking for.

Regards,

Tom