Keep values in between a range (dates and times)

[Tim Fattouh]

Hello everyone,
I am quite new to stata so I would really appreciate your help.
I have date-time variables which I converted from string and they are in this form:
09jan2013 13:43:18 (together in one cell).
I would like to keep variables from the same day but in a specific time range e.g. all the variables on 09jan2013 in the range of 19:00:00 to 19:30:00.
Thank you in advance,
Tim

[Wouter Wakker]

Maybe this example will point you in the right direction.

. clear

. input str20 datetime_str

             datetime_str
  1. "09jan2013 13:43:18" 
  2. "09jan2013 19:23:18"
  3. "09jan2013 19:30:00"
  4. "09jan2013 19:30:01"
  5. "10jan2013 13:43:18" 
  6. "10jan2013 19:23:18"
  7. "10jan2013 19:30:00"
  8. "10jan2013 19:30:01"
  9. end

. 
. gen double datetime_num = clock(datetime_str, "DMY hms")

. gen date = dofc(datetime_num)

. gen time = hh(datetime_num) + mm(datetime_num) / 60 + ss(datetime_num) / 3600

. 
. format datetime_num %tc

. format date %td

. list, sepby(date)

     +----------------------------------------------------------------+
     |       datetime_str         datetime_num        date       time |
     |----------------------------------------------------------------|
  1. | 09jan2013 13:43:18   09jan2013 13:43:18   09jan2013   13.72167 |
  2. | 09jan2013 19:23:18   09jan2013 19:23:18   09jan2013   19.38833 |
  3. | 09jan2013 19:30:00   09jan2013 19:30:00   09jan2013       19.5 |
  4. | 09jan2013 19:30:01   09jan2013 19:30:01   09jan2013   19.50028 |
     |----------------------------------------------------------------|
  5. | 10jan2013 13:43:18   10jan2013 13:43:18   10jan2013   13.72167 |
  6. | 10jan2013 19:23:18   10jan2013 19:23:18   10jan2013   19.38833 |
  7. | 10jan2013 19:30:00   10jan2013 19:30:00   10jan2013       19.5 |
  8. | 10jan2013 19:30:01   10jan2013 19:30:01   10jan2013   19.50028 |
     +----------------------------------------------------------------+

. 
. keep if inrange(time, 19, 19.5) & inlist(date, td(09jan2013))
(6 observations deleted)

. list

     +----------------------------------------------------------------+
     |       datetime_str         datetime_num        date       time |
     |----------------------------------------------------------------|
  1. | 09jan2013 19:23:18   09jan2013 19:23:18   09jan2013   19.38833 |
  2. | 09jan2013 19:30:00   09jan2013 19:30:00   09jan2013       19.5 |
     +----------------------------------------------------------------+

[Tim Fattouh]

It worked perfectly !! thank you very much Mr Wakker

[William Lisowski]

Building on the technique given by Wouter Wakker in post #2, the following example makes it easier to specify "complicated" times. I present this not as an improvement for the current problem, but rather an extension to the general technique, should someone with a complicated time range find this post at a later date.

. gen double datetime_num = clock(datetime_str, "DMY hms")

. gen date = dofc(datetime_num)

. gen double time = datetime_num-dhms(date,0,0,0)

. format datetime_num %tcHH:MM:SS.sss

. format date %td

. format time %tcHH:MM:SS.sss

. generate keepthis = inrange(time, hms(18,59,59.5), hms(19,30,0.5)) & inlist(date, td(09jan2013))

. list, sepby(date) noobs

  +---------------------------------------------------------------------------+
  |         datetime_str   datetime_num        date           time   keepthis |
  |---------------------------------------------------------------------------|
  |   09jan2013 13:43:18   13:43:18.000   09jan2013   13:43:18.000          0 |
  |   09jan2013 18:59:59   18:59:59.000   09jan2013   18:59:59.000          0 |
  | 09jan2013 18:59:59.7   18:59:59.700   09jan2013   18:59:59.700          1 |
  |   09jan2013 19:23:18   19:23:18.000   09jan2013   19:23:18.000          1 |
  |   09jan2013 19:30:00   19:30:00.000   09jan2013   19:30:00.000          1 |
  | 09jan2013 19:30:00.5   19:30:00.500   09jan2013   19:30:00.500          1 |
  |   09jan2013 19:30:01   19:30:01.000   09jan2013   19:30:01.000          0 |
  |---------------------------------------------------------------------------|
  |   10jan2013 13:43:18   13:43:18.000   10jan2013   13:43:18.000          0 |
  |   10jan2013 19:23:18   19:23:18.000   10jan2013   19:23:18.000          0 |
  |   10jan2013 19:30:00   19:30:00.000   10jan2013   19:30:00.000          0 |
  |   10jan2013 19:30:01   19:30:01.000   10jan2013   19:30:01.000          0 |
  +---------------------------------------------------------------------------+