I have 4 columns in the mock data set (File attached below). The column "Companys" is grouped by column "Month-Year" and "State". Each "Companys" column value is associated to a value in column "Sectcor". I want find what values are missing in each group of Month-Year and State Column for example Sector "DK" has Companys "C" and "D" Associated to it but for group Jan-2021, CA we have 2 rows associated to it with Companys "C" and "D" for Sector "DK" but in group Feb-2021, CA there is only one row associated to it with Companys "D" for Setcor "DK". I want to insert the missing row for Companys "C" like Feb-2021, CA, "C" and 0 for the count column.
I want the row in red. Please help with this problem!