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st: wrong datetime results with clock() -- sometimes


From   Rebecca Pope <rebecca.a.pope@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: wrong datetime results with clock() -- sometimes
Date   Fri, 5 Jul 2013 14:05:41 -0500

Hello,
I am trying to convert a variable with datetime observations currently
stored as string to a numeric format. Here is a sample of my data
after issuing these command:

gen datetime = clock(timestr,"MDYhms")
format datetime %tc

. list timestr datetime in 1/10, noobs clean
                 timestr             datetime
     2/8/2011 9:50:51 PM   08feb2011 21:50:37
    2/12/2011 4:15:40 PM   12feb2011 16:14:48
    2/11/2011 3:26:12 PM   11feb2011 15:27:08
    5/15/2011 9:46:41 AM   15may2011 09:46:59
    5/20/2011 8:32:28 PM   20may2011 20:31:39
     2/7/2011 2:15:40 PM   07feb2011 14:16:37
    5/25/2011 7:07:57 PM   25may2011 19:08:51
     5/9/2011 3:00:42 PM   09may2011 15:01:44
    5/22/2011 3:24:57 PM   22may2011 15:25:01
     5/9/2011 7:09:46 PM   09may2011 19:10:46

As you can see, the converted values are a few seconds off from the
time stored in the string variable.

I don't think that this is a Stata problem per se because if I convert
a single observation, the correct time is displayed:
. di %tc clock("2/8/2011 9:50:51 PM", "MDYhms")
08feb2011 21:50:51

That said, I'm not the first person to encounter this
(http://www.stata.com/statalist/archive/2011-10/msg00687.html).
However, I don't see that a solution/reason was ever provided.

My best guess in the face of this was a hidden character in the
variable. I checked for this with the following:
replace timestr = subinstr(" "+timestr+" "," ","-",.) in 1/10
                   timestr
     -2/8/2011-9:50:51-PM-
    -2/12/2011-4:15:40-PM-
    -2/11/2011-3:26:12-PM-
    -5/15/2011-9:46:41-AM-
    -5/20/2011-8:32:28-PM-
     -2/7/2011-2:15:40-PM-
    -5/25/2011-7:07:57-PM-
     -5/9/2011-3:00:42-PM-
    -5/22/2011-3:24:57-PM-
     -5/9/2011-7:09:46-PM-

As you can see, the hyphens are right next to the text, so I don't
think there is anything lurking at the beginning or end of the text
that isn't displaying.

Does anyone have other suggestions?

Thanks,
Rebecca
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