Hello statalist members,
with reference to my last post on https://www.statalist.org/forums/for...gression/page3
i want to use weekly data, for that very purpose i need date format based on year and week, and i also need the total number of weeks in a year,i also want to take leads and lags of my variable of interest, and for that, i have to tsset or xtset my data.to avoid the problem of
repeated time values within panel
i have created a new variable dategroup

Code:
egen dategroup=group( year week)
so that i can tsset my data on the base of this variable and firm-ID (code) for further work as a week variable.But i need to use a proper way as compare to dategroup variable to deal with it.
could you please guide me how can i format my date variable trdwnt , so that i can use it for my further work, and also to calculate the total number of trading weeks in a year.
In below example week 2002-07 and 2002-08 are missings, so i want to deal with such like missing values as well.


My dataset example is

----------------------- copy starting from the next line -----------------------
Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input long code str7 trdwnt str10 opndt float wopnprc str10 clsdt float wclsprc int year byte week float dategroup
2 "2002-01" "2002-01-04" 13.01 "2002-01-04" 12.99 2002  1   1
2 "2002-02" "2002-01-07"  12.9 "2002-01-11" 12.31 2002  2   2
2 "2002-03" "2002-01-14"  12.2 "2002-01-18" 11.28 2002  3   3
2 "2002-04" "2002-01-21" 11.27 "2002-01-25"    12 2002  4   4
2 "2002-05" "2002-01-28" 11.76 "2002-02-01" 12.49 2002  5   5
2 "2002-06" "2002-02-04" 12.45 "2002-02-08"  12.5 2002  6   6
2 "2002-09" "2002-02-25" 12.91 "2002-03-01" 12.47 2002  9   7
2 "2002-10" "2002-03-04" 12.45 "2002-03-08"  13.4 2002 10   8
2 "2002-11" "2002-03-11" 13.39 "2002-03-15" 13.01 2002 11   9
2 "2002-12" "2002-03-18"  13.4 "2002-03-22" 13.12 2002 12  10
2 "2002-13" "2002-03-25"  13.1 "2002-03-29" 12.68 2002 13  11
2 "2002-14" "2002-04-01"  12.6 "2002-04-05" 12.66 2002 14  12
2 "2002-15" "2002-04-08" 12.61 "2002-04-12" 12.72 2002 15  13
2 "2002-16" "2002-04-15" 12.72 "2002-04-19" 12.47 2002 16  14
2 "2002-17" "2002-04-22" 12.35 "2002-04-26" 12.33 2002 17  15
2 "2002-18" "2002-04-29" 12.33 "2002-04-30" 12.42 2002 18  16
2 "2002-19" "2002-05-08"  12.4 "2002-05-10" 12.14 2002 19  17
2 "2002-20" "2002-05-13" 12.06 "2002-05-17" 11.48 2002 20  18
2 "2002-21" "2002-05-20" 11.51 "2002-05-24" 11.82 2002 21  19
2 "2002-22" "2002-05-27" 11.94 "2002-05-31"  11.3 2002 22  20
2 "2002-23" "2002-06-03"  11.2 "2002-06-07" 11.42 2002 23  21
2 "2002-24" "2002-06-10" 11.42 "2002-06-11" 11.43 2002 24  22
2 "2002-25" "2002-06-18"  11.5 "2002-06-21"  11.9 2002 25  23
2 "2002-26" "2002-06-24" 13.09 "2002-06-28" 13.21 2002 26  24
2 "2002-27" "2002-07-01" 13.27 "2002-07-05" 12.83 2002 27  25
2 "2002-28" "2002-07-08" 12.85 "2002-07-12" 12.59 2002 28  26
2 "2002-29" "2002-07-15" 12.55 "2002-07-19" 12.52 2002 29  27
2 "2002-30" "2002-07-22" 12.51 "2002-07-26" 12.01 2002 30  28
2 "2002-31" "2002-07-29" 12.05 "2002-08-02" 12.13 2002 31  29
2 "2002-32" "2002-08-05" 12.18 "2002-08-09"  11.9 2002 32  30
2 "2002-33" "2002-08-12" 11.87 "2002-08-16" 11.79 2002 33  31
2 "2002-34" "2002-08-19" 11.78 "2002-08-23" 12.14 2002 34  32
2 "2002-35" "2002-08-26"  12.1 "2002-08-30" 11.87 2002 35  33
2 "2002-36" "2002-09-02" 11.87 "2002-09-06" 11.72 2002 36  34
2 "2002-37" "2002-09-09"  11.7 "2002-09-13" 11.58 2002 37  35
2 "2002-38" "2002-09-16" 11.57 "2002-09-20" 11.55 2002 38  36
2 "2002-39" "2002-09-23" 11.53 "2002-09-27" 11.43 2002 39  37
2 "2002-41" "2002-10-08" 11.38 "2002-10-11"  11.1 2002 41  38
2 "2002-42" "2002-10-14" 11.19 "2002-10-18"  11.1 2002 42  39
2 "2002-43" "2002-10-21"  11.1 "2002-10-25"  11.1 2002 43  40
2 "2002-44" "2002-10-28"    11 "2002-11-01" 11.05 2002 44  41
2 "2002-45" "2002-11-04" 11.05 "2002-11-08" 11.24 2002 45  42
2 "2002-46" "2002-11-11"  11.2 "2002-11-15" 10.09 2002 46  43
2 "2002-47" "2002-11-18" 10.09 "2002-11-22" 10.22 2002 47  44
2 "2002-48" "2002-11-25" 10.21 "2002-11-29" 10.13 2002 48  45
2 "2002-49" "2002-12-02" 10.13 "2002-12-06"  9.86 2002 49  46
2 "2002-50" "2002-12-09"   9.8 "2002-12-13"  9.77 2002 50  47
2 "2002-51" "2002-12-16"  9.78 "2002-12-20"  9.94 2002 51  48
2 "2002-52" "2002-12-23"  9.91 "2002-12-27"  9.79 2002 52  49
2 "2002-53" "2002-12-30"   9.7 "2002-12-31"  9.65 2002 53  50
2 "2003-01" "2003-01-02"  9.48 "2003-01-03"  9.09 2003  1  51
2 "2003-02" "2003-01-06"  9.08 "2003-01-10"  9.54 2003  2  52
2 "2003-03" "2003-01-13"   9.5 "2003-01-17" 10.16 2003  3  53
2 "2003-04" "2003-01-20" 10.16 "2003-01-24"  9.96 2003  4  54
2 "2003-05" "2003-01-27"  9.96 "2003-01-29" 10.07 2003  5  55
2 "2003-07" "2003-02-10"  10.1 "2003-02-14" 10.26 2003  7  56
2 "2003-08" "2003-02-17" 10.25 "2003-02-21"  9.94 2003  8  57
2 "2003-09" "2003-02-24"  9.94 "2003-02-28" 10.33 2003  9  58
2 "2003-10" "2003-03-03" 10.35 "2003-03-07"  10.9 2003 10  59
2 "2003-11" "2003-03-10"  10.9 "2003-03-14" 11.31 2003 11  60
2 "2003-12" "2003-03-17" 11.32 "2003-03-21" 11.42 2003 12  61
2 "2003-13" "2003-03-24" 11.46 "2003-03-28" 11.55 2003 13  62
2 "2003-14" "2003-03-31" 11.58 "2003-04-04" 11.98 2003 14  63
2 "2003-15" "2003-04-07"    12 "2003-04-11" 12.76 2003 15  64
2 "2003-16" "2003-04-14" 12.78 "2003-04-18" 13.89 2003 16  65
2 "2003-17" "2003-04-21" 13.79 "2003-04-25" 12.21 2003 17  66
2 "2003-18" "2003-04-28" 12.01 "2003-04-30" 12.84 2003 18  67
2 "2003-20" "2003-05-12" 12.92 "2003-05-16" 13.88 2003 20  68
2 "2003-21" "2003-05-19" 13.93 "2003-05-23"  6.79 2003 21  69
2 "2003-22" "2003-05-26"  6.79 "2003-05-30"  7.13 2003 22  70
2 "2003-23" "2003-06-02"   7.1 "2003-06-06"  6.78 2003 23  71
2 "2003-24" "2003-06-09"  6.78 "2003-06-13"  6.82 2003 24  72
2 "2003-25" "2003-06-16"  6.79 "2003-06-20"  6.41 2003 25  73
2 "2003-26" "2003-06-23"   6.4 "2003-06-27"  5.83 2003 26  74
2 "2003-27" "2003-06-30"   5.7 "2003-07-04"     6 2003 27  75
2 "2003-28" "2003-07-07"     6 "2003-07-11"  6.21 2003 28  76
2 "2003-29" "2003-07-14"  6.21 "2003-07-18"  6.25 2003 29  77
2 "2003-30" "2003-07-21"   6.2 "2003-07-25"  6.16 2003 30  78
2 "2003-31" "2003-07-28"  6.16 "2003-08-01"  6.39 2003 31  79
2 "2003-32" "2003-08-04"  6.38 "2003-08-08"  6.49 2003 32  80
2 "2003-33" "2003-08-11"  6.48 "2003-08-15"   6.5 2003 33  81
2 "2003-34" "2003-08-18"  6.52 "2003-08-22"  6.64 2003 34  82
2 "2003-35" "2003-08-25"   6.6 "2003-08-29"  6.46 2003 35  83
2 "2003-36" "2003-09-01"  6.45 "2003-09-05"  6.34 2003 36  84
2 "2003-37" "2003-09-08"  6.34 "2003-09-12"  6.04 2003 37  85
2 "2003-38" "2003-09-15"  6.02 "2003-09-19"  5.81 2003 38  86
2 "2003-39" "2003-09-22"  5.83 "2003-09-26"  5.91 2003 39  87
2 "2003-40" "2003-09-29"   5.9 "2003-09-30"  5.86 2003 40  88
2 "2003-41" "2003-10-08"  5.88 "2003-10-10"  6.05 2003 41  89
2 "2003-42" "2003-10-13"  6.09 "2003-10-17"   5.9 2003 42  90
2 "2003-43" "2003-10-20"  5.88 "2003-10-24"  6.06 2003 43  91
2 "2003-44" "2003-10-28"  6.02 "2003-10-31"  5.94 2003 44  92
2 "2003-45" "2003-11-03"  5.89 "2003-11-07"  5.95 2003 45  93
2 "2003-46" "2003-11-10"  5.95 "2003-11-14"  5.81 2003 46  94
2 "2003-47" "2003-11-17"  5.81 "2003-11-21"  5.87 2003 47  95
2 "2003-48" "2003-11-24"  5.87 "2003-11-28"  5.91 2003 48  96
2 "2003-49" "2003-12-01"  5.91 "2003-12-05"  6.02 2003 49  97
2 "2003-50" "2003-12-08"  6.01 "2003-12-12"  6.11 2003 50  98
2 "2003-51" "2003-12-15"  6.12 "2003-12-19"     6 2003 51  99
2 "2003-52" "2003-12-22"     6 "2003-12-26"  6.53 2003 52 100
end
label var code "Stkcd" 
label var trdwnt "Trading Week '" 
label var opndt "Weekly Opening Date '" 
label var wopnprc "Weekly Opening Price '" 
label var clsdt "Weekly Closing Date '" 
label var wclsprc "Weekly Closing Price '" 
label var dategroup "group(year week)"
------------------ copy up to and including the previous line ------------------

Listed 100 out of 1755974 observations
Use the count() option to list more


Best regards,