reshape.sas

data bank_mod (drop = i month Expense) ;
    set bank ;
    by CardID ;
    if _n_ = 1 then do ;
        array Expensex(3) Expense1 - Expense3 ;
    end ;
    retain Expense1 - Expense3 ;
    if first.CardID then do ;
        do i = 1 to 3 ;
            Expensex(i) = . ;
        end ;
    end ;
    Expensex(month) = Expense ;
    if last.CardID then output ;
run ;