Comparing dates problem

[kyos...@gmail.com]

Hi,

I am writing a reminder program for our Zimbra email client. One of
the requirements I was given was to automatically increment or
decrement the display to show something like the following:

5 minutes until appointment

or

10 minutes past your appointment

Either way, as each minute goes by, I need to increment it or
decrement it. I am having trouble finding a coherent way to take the
same date and compare just the number of minutes between them to find
the difference. Like if I have an appointment at 9:30 a.m. and the app
is loaded at 8 a.m., I need to know the number of minutes or hours and
minutes until the appointment.

I have looked at the dateutils module and it has many comparison
methods, but they seem to only return the number of days or seconds.

Any ideas would be great!

Mike

[John Machin]

Ermmm ... what's wrong with

minutes = seconds / 60.0
hours = minutes / 60.0

?

[Tim Golden]

kyos...@gmail.com wrote:
> I am writing a reminder program for our Zimbra email client. One of
> the requirements I was given was to automatically increment or
> decrement the display to show something like the following:
>
> 5 minutes until appointment
>
> or
>
> 10 minutes past your appointment
>
>
> Either way, as each minute goes by, I need to increment it or
> decrement it. I am having trouble finding a coherent way to take the
> same date and compare just the number of minutes between them to find
> the difference. Like if I have an appointment at 9:30 a.m. and the app
> is loaded at 8 a.m., I need to know the number of minutes or hours and
> minutes until the appointment.

Not the most elegant piece of code on earth,
but this piece of code works for me (cut-and-pasted
directly from a working project, so doesn't
*exactly* match your requirement).

<code>
def deltastamp (now, then):

def pluralise (base, n):
if n > 1:
return "%d %ss" % (n, base)
else:
return "%d %s" % (n, base)

if now > then:
output_format = "%s ago"
delta = now - then
else:
output_format = "in %s"
delta = then - now

days = delta.days
if days <> 0:
wks, days = divmod (days, 7)
if wks > 0:
output = pluralise ("wk", wks)
else:
output = pluralise ("day", days)
else:
mins, secs = divmod (delta.seconds, 60)
hrs, mins = divmod (mins, 60)
if hrs > 0:
output = pluralise ("hr", hrs)
elif mins > 0:
output = pluralise ("min", mins)
else:
output = pluralise ("sec", secs)

return output_format % output

</code>

TJG

[kyos...@gmail.com]

I'm sure there is a hack for doing something like what you suggest,
but it would be messy. The problem is that I get a datetime object
returned and division really isn't something you can do to one of
those objects. Besides, if I had seconds returned, I would want to
multiply by 60, not divide.

Maybe I misunderstand you.

Mike

[kyos...@gmail.com]

On May 10, 2:37 am, Tim Golden <m...@timgolden.me.uk> wrote:

Thanks for the advice. I think this will work for me with some minor
tweaking. If not, I will post again.

Mike

[Carsten Haese]

On Thu, 2007-05-10 at 11:52 -0700, kyos...@gmail.com wrote:
> I'm sure there is a hack for doing something like what you suggest,
> but it would be messy. The problem is that I get a datetime object
> returned and division really isn't something you can do to one of
> those objects. Besides, if I had seconds returned, I would want to
> multiply by 60, not divide.

If you subtract that datetime object from the current datetime, you'll
get a timedelta object that gives you the number of days and seconds
(and microseconds, if you care) between the two datetimes:

>>> import datetime
>>> dt1 = datetime.datetime(2007,5,1,12,0,0)
>>> dt2 = datetime.datetime.now()
>>> delta = dt2 - dt1
>>> delta.days
9
>>> delta.seconds
11219

Now, if 60 seconds are one minute, 11219 seconds are how many minutes?
(Answer left as an exercise for the reader.)

Hope this helps,

--
Carsten Haese
http://informixdb.sourceforge.net

[kyos...@gmail.com]

Of course, after posting this, I felt very stupid...

[John Machin]

Maybe it's mutual -- hack? messy? multiply? Where I come from, 180
seconds is (180 / 60 = 3) minutes. 180 seconds * 60 is 10800 sixtieths-
of-a-second, which appears to be travelling away from a solution to
your problem.

You have *TWO* datetime objects, (say) appt_dt and now_dt.

delta =appt_dt - now_dt # delta is a timedelta object.
# calculate difference in minutes
mins = delta.days * 24 * 60 + delta.seconds // 60

Have you not read Tim Golden's response?

[kyos...@gmail.com]

Yeah. I said I felt stupid. I'm sorry. I was looking at the problem
from the wrong direction.

Mike