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Topic: Daylight savings time in DatePlus.
Replies: 4   Last Post: Jan 23, 2012 2:58 AM

 Messages: [ Previous | Next ]
 hmichel@cox.net Posts: 122 Registered: 1/29/05
Re: Daylight savings time in DatePlus.
Posted: Jan 21, 2012 5:22 AM

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@mit.edu]
Sent: Friday, January 20, 2012 12:52 AM
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

Date Subject Author
1/21/12 hmichel@cox.net
1/21/12 hmichel@cox.net
1/23/12 W. Craig Carter