Re: st: Days between

[David Kantor <kantor.d@att.net>]

At 09:20 AM 1/9/2013, Damian wrote:

> I have two date formats which I have imported from Excel.  The first
> is a in dd/mm/yyyy hh:mm format (e.g. 22/04/2011 12:08).  The second
> is dd/mm/yy (e.g. 22/08/2012). Both dates are currently stored as
> float and formatted in %tc.
>
> I would like to calculate the days between these two dates.  I was
> able to when both dates were in dd/mm/yy.  However, with the inclusion
> of hh:mm I am no longer able to.
>
> How would I calculate the days between?

Presumably, the variable in what you described as dd/mm/yyyy hh:mm 
format actually
has a %tc format. It does not make sense that the other is %tc. Is it 
really %td ??

You need to generate a new variable that has a %td format and which 
ignores the hh:mm part of the original values. Use the dofc function.

gen long newvar = dofc(origvar)
format newvar %td

Now you can compare newvar to the other date variable -- that is, 
take the difference.

(You could do this as a -replace- if you don't mind losing information.
You could also skip the replace or generate:
 gen int datediff = date1 - dofc(date2)
-- assuming that date2 is %tc and date1 is %td, or...
 gen int datediff = dofc(date1) - dofc(date2)
if they are both %tc.
)

HTH
--David

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