Logic - Average value for a particular Customer + Period

Question

Hello Experts,
Please help me in the Logic to find out Average for the below scenario:
This is the Output:
Customer
Period
Payment Timeliness
Cust-001
01/97
-4
Cust-001
01/97
2
Cust-001
01/97
3
Cust-001
04/97
3
Cust-001
04/97
5
Cust-001
06/97
-4
Cust-001
07/97
2
Cust-001
08/97
3
Cust-002
09/97
5
Cust-002
09/97
4
Cust-002
10/97
6
Cust-002
10/97
-2
Cust-002
12/97
-4
Requirement is:
Customer
Period
Payment Timeliness
Cust-001
01/97
0.333
Cust-001
04/97
4
Cust-001
06/97
-4
Cust-001
07/97
2
Cust-001
08/97
3
Cust-002
09/97
4.5
Cust-002
10/97
2
Cust-002
12/97
-4
Display the Average of all the Payment Timeliness for a particular Month as shown above.
My Code is:
*&      Form  fetch_data
FORM fetch_data .
  SELECT bukrs
         belnr
         gjahr
         blart
         bldat
         budat
         monat
   FROM  bkpf
   INTO  TABLE g_t_bkpf
   WHERE bukrs EQ '0470'
   AND   gjahr EQ p_year
   AND ( blart EQ 'EZ'
   OR    blart EQ 'DZ' )
   AND   monat IN s_month.
  IF sy-subrc EQ 0.
    SELECT bukrs
           belnr
           gjahr
           augdt
           buzei
           shkzg
           kunnr
           zfbdt
           zbd1t
           zbd2t
           zbd3t
           rebzg
     FROM  bseg
     INTO  TABLE g_t_bseg
     FOR ALL ENTRIES IN g_t_bkpf
     WHERE bukrs EQ g_t_bkpf-bukrs
     AND   belnr EQ g_t_bkpf-belnr
     AND   gjahr EQ g_t_bkpf-gjahr
     AND   kunnr IN s_kunnr.
    IF sy-subrc EQ 0.
    ELSE.
      WRITE:/'No Data Found'.
    ENDIF.
  ENDIF.
ENDFORM.                    " fetch_data
FORM display_paystats .
  DATA: l_due_date     TYPE faedt_fpos,
        l_timeliness   TYPE p,
        l_kunnr        type kunnr,
        l_counter      type i,
        l_period       type char5,
        l_tot_timeli   type p.
  IF g_t_bseg IS NOT INITIAL.
    WRITE: /10 'Customer ', 24 'Period ', 35 'Payment Timeliness'.
    WRITE: /10 sy-uline(44).
    LOOP AT g_t_bseg INTO g_wa_bseg.
      CLEAR l_due_date.
      CALL FUNCTION 'NET_DUE_DATE_GET'
        EXPORTING
          i_zfbdt       = g_wa_bseg-zfbdt
          i_zbd1t       = g_wa_bseg-zbd1t
          i_zbd2t       = g_wa_bseg-zbd2t
          i_zbd3t       = g_wa_bseg-zbd3t
          i_shkzg       = g_wa_bseg-shkzg
          i_rebzg       = g_wa_bseg-rebzg
       IMPORTING
         e_faedt       = l_due_date.
      READ TABLE g_t_bkpf INTO g_wa_bkpf WITH KEY
                                          bukrs = g_wa_bseg-bukrs
                                          belnr = g_wa_bseg-belnr
                                          gjahr = g_wa_bseg-gjahr.
      IF sy-subrc EQ 0.
        l_timeliness = g_wa_bkpf-budat - l_due_date.
      ENDIF.
      CLEAR g_wa_paystat.
      g_wa_paystat-kunnr = g_wa_bseg-kunnr.
      CONCATENATE g_wa_bseg-augdt+4(2) '/' g_wa_bseg-augdt+2(2) INTO g_wa_paystat-period.
      g_wa_paystat-timeli = l_timeliness.
      APPEND g_wa_paystat TO g_t_paystat.
      CLEAR : g_wa_bseg, g_wa_paystat.
    ENDLOOP.
    SORT g_t_paystat BY period.
    LOOP AT g_t_paystat INTO g_wa_paystat.
      WRITE:/10 g_wa_paystat-kunnr, 24 g_wa_paystat-period, 35 g_wa_paystat-timeli.
    ENDLOOP.
  ENDIF.
ENDFORM.                    " display_paystats
Where should I check the condition?
I thought of assigning the Period / KUNNR in a Variable; then compare from the second record.
But then how can I skip the check for 1st time inside a Loop?
Since this is BSEG/BKPF entries; it is slow. So, please suggest some logic that doesn't affect the performance.
Is it possible to write this logic within BSEG LOOP?
Appreciate your help.
Thank you!
Thanks & Regards,
Sowmya

Answer 1

Found out by myself
Closing the thread.
SORT g_t_paystat BY kunnr period.
    LOOP AT g_t_paystat INTO g_wa_paystat.
      l_kunnr = g_wa_paystat-kunnr.
      l_period = g_wa_paystat-period.
      l_tot_timeli = g_wa_paystat-timeli.
      IF sy-tabix NE 1.
        READ TABLE g_t_paystat INTO g_wa_paystat1 WITH KEY kunnr  = l_kunnr
                                                           period = l_period.
        IF sy-subrc EQ 0.
          l_counter = l_counter + 1.
          l_tot_timeli = l_tot_timeli + 1.
        ELSE.
          g_wa_paystat-timeli = l_tot_timeli / l_counter.
          MODIFY g_t_paystat FROM g_wa_paystat TRANSPORTING timeli WHERE kunnr  = l_kunnr
                                                                   AND   period = l_period.
          CLEAR:
            l_counter,
            l_tot_timeli.
        ENDIF.
      ENDIF.
    ENDLOOP.
    DELETE ADJACENT DUPLICATES FROM g_t_paystat COMPARING kunnr period.
    LOOP AT g_t_paystat INTO g_wa_paystat.
      WRITE:/10 g_wa_paystat-kunnr, 24 g_wa_paystat-period, 35 g_wa_paystat-timeli.
    ENDLOOP.