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Re: Daylight savings time in DatePlus.


Thank you Hans,
Very nice.

However, it seems that this can't be generalized without direct input of 
the daylight savings time shifts for each region where the data is 
taken.

I suppose there may be case for curated data in this case. Although I 
don't imagine that it would have a large audience.  Astronomical data 
comes to mind as one possible place where curated data and methods would 
be useful---there is a current debate about adding a leap second.

In any case, many thanks for your time and effort, Craig


W Craig Carter
Professor of Materials Science, MIT



On Jan 20, 2012, at Fri, Jan 20, 12 ---11:03 PM, Hans Michel wrote:

> Craig:
>
> Working with just your example, using time zones
>
> Map[Function[
>  DateString[ #1, If[Last[#1] < 2, TimeZone -> -6, TimeZone -> -5]]],
> Map[Function[DatePlus[{2010, 1, 1, 1}, {#1, "Hour"}]],
>  Range[1728, 1738]]]
>
> {Sun 14 Mar 2010 01:00:00,Sun 14 Mar 2010 03:00:00,Sun 14 Mar 2010
> 04:00:00,Sun 14 Mar 2010 05:00:00,Sun 14 Mar 2010 06:00:00,Sun 14 Mar 2010
> 07:00:00,Sun 14 Mar 2010 08:00:00,Sun 14 Mar 2010 09:00:00,Sun 14 Mar 2010
> 10:00:00,Sun 14 Mar 2010 11:00:00,Sun 14 Mar 2010 12:00:00}
>
> Hans
>
> -----Original Message-----
> From: W Craig Carter [mailto:ccarter at mit.edu]
> Sent: Friday, January 20, 2012 12:52 AM
> To: mathgroup at smc.vnet.net
> Subject: Daylight savings time in DatePlus.
>
> Hello,
> I need to account for daylight savings time in list of data representing
> each hour in year 2010. I would like to correlate that with other data
> taken at 15 second intervals in the same year.
>
> In 2010 daylight savings time in the US began on 14 March 2AM.
>
> DateDifference[{2010, 1, 1, 1}, {2010, 3, 14, 1}, "Hour"] (*1728 hours after
> beginning of year*)
>
> DateString /@ (DatePlus[{2010, 1, 1, 1}, {#, "Hour"}] & /@Range[1728, 1738])
>
> (*doesn't reflect that 3AM should follow 1AM*)
>
>
> In hindsight, this is not surprising because daylight savings time
> shifts are not standardized intranationally or internationally.  I don't
> see any clever work-around. Does anyone else?
>
> Craig
>
>
>
> W Craig Carter
> Professor of Materials Science, MIT
>
>
>
>




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