Change a row value for a single visual using DAX

[P0werBIn00b]

I am trying the use a column as legend in donut chart. The column value has nulls too.
I want to change the "nulls" to "Not Specified" just for the donut chart instead of transforming it in the dataset. Is that possible using DAX or something?

Please Help.
Thank you in advance, Sir.

[eliasayyy · Accepted solution]

hello just add a new calculated column to your tble 

New Column = 
SWITCH(
   TRUE(),
    'Table'[Category] = BLANK(),"Not Specified",
    'Table'[Category]
)

using measures isnt possible for now