Dear list, I need to transform the DateTime of my GPS data from: "666.1751" into "yyyy/mm/dd hh:mm:ss" I have the following code: d$Date <- ISOdatetime(2009, 1, 1, 0, 0, 0, tz = "GMT")+d$Date*(24*3600) This gives me: 2010-10-29 04:12:09, which is wrong. It should be 2010-10-29 06:12:09 Another example: 418.3219 corresponds to: 2010-02-23 07:43:30, but it should be 2010-02-23 08:43:30. However, not always is the difference + 2 h, it's sometimes less or more. There are a lot of postings here regarding ISOdatetime, but I'm still not able to solve this . Any ideas or suggestions will be very much appreciated. Best regards, Julia PS. I've tried to find the answer in all sorts of R help forums and also in my R books - no luck so far. Maybe I'm missunderstanding the entire ISOdatetime function? -- View this message in context: http://r.789695.n4.nabble.com/Incorrect-DateTime-using-ISOdatetime-in-R-tp4313470p4313470.html Sent from the R help mailing list archive at Nabble.com.
666.1751 sure seems like it should return 2010-10-29 04:12:09 based on your example. 666.1751 days from 2009-01-01 is 2010-10-29 + some hours/min/seconds. 0.1751 days * 24 hrs/day = 4.2024 (i.e. 4:00AM + some minutes). 0.2024 hours * 60 min/hr = 12.144 (i.e. 12 minutes + some seconds). 0.144 minutes * 60 sec/min = 8.64 (i.e. 8.64 seconds). Put it all together and I get 2010-10-29 04:12:08.64 in the GMT time zone. What makes you think it should be 2010-10-29 06:12:09? Are you running into a time zone issue, such as your GPS adjusting its time zone and reported the time based on the time zone where a reading was taken? If you crossed between time zones for some of your readings it might explain the fluctuating difference between the answer you expect and the answer that ISOdatetime gives you. -Luke On Fri, Jan 20, 2012 at 6:59 AM, Sula2011 <julia.somma at gmx.de> wrote:> > Dear list, > > I need to transform the DateTime of my GPS data from: > > "666.1751" into "yyyy/mm/dd hh:mm:ss" > > I have the following code: > > d$Date <- ISOdatetime(2009, 1, 1, 0, 0, 0, tz = "GMT")+d$Date*(24*3600) > > This gives me: 2010-10-29 04:12:09, which is wrong. It should be 2010-10-29 > 06:12:09 > > Another example: > > 418.3219 corresponds to: 2010-02-23 07:43:30, but it should be 2010-02-23 > 08:43:30. > > However, not always is the difference + 2 h, it's sometimes less or more. > > There are a lot of postings here regarding ISOdatetime, but I'm still not > able to solve this . Any ideas or suggestions will be very much appreciated. > > Best regards, > > Julia > > PS. I've tried to find the answer in all sorts of R help forums and also in > my R books - no luck so far. Maybe I'm missunderstanding the entire > ISOdatetime function? > > -- > View this message in context: http://r.789695.n4.nabble.com/Incorrect-DateTime-using-ISOdatetime-in-R-tp4313470p4313470.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.
> -----Original Message----- > From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] > On Behalf Of Sula2011 > Sent: Friday, January 20, 2012 7:00 AM > To: r-help at r-project.org > Subject: [R] Incorrect DateTime using ISOdatetime in R > > Dear list, > > I need to transform the DateTime of my GPS data from: > > "666.1751" into "yyyy/mm/dd hh:mm:ss" > > I have the following code: > > d$Date <- ISOdatetime(2009, 1, 1, 0, 0, 0, tz = "GMT")+d$Date*(24*3600) > > This gives me: 2010-10-29 04:12:09, which is wrong. It should be 2010-10- > 29 > 06:12:09 > > Another example: > > 418.3219 corresponds to: 2010-02-23 07:43:30, but it should be 2010-02-23 > 08:43:30. > > However, not always is the difference + 2 h, it's sometimes less or more. > > There are a lot of postings here regarding ISOdatetime, but I'm still not > able to solve this . Any ideas or suggestions will be very much > appreciated. > > Best regards, > > Julia > > PS. I've tried to find the answer in all sorts of R help forums and also > in > my R books - no luck so far. Maybe I'm missunderstanding the entire > ISOdatetime function? >Julia, are the times from your GPS really GMT times, or are they your local time (it looks like you are in Germany)? It looks like you are dealing with local times that are further complicated by changes between daylight and standard time. Could that be the issue? Dan Daniel Nordlund Bothell, WA USA