I have a table with variables 'Date', 'ID', Price', 'Volumn', all with daily value. The 'Date' repeats itself. Now I want to first group the table based on 'Date', and within each group (namely each date), I want to sort the table according to 'Price', from high to low. I know varfun can help me gruop the table and do the sorting, but the output will not contain 'ID' and 'Volumn'. I still want to researve the other variables. What shall I do?