[R] order a data frame by date with orderl

[Jim Holtman]

Is the a daylight saving time problem?  Check your timezone and see when it occurred; these times might not be legal.

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On May 16, 2012, at 3:27, Benedikt Gehr <benedikt.gehr at ieu.uzh.ch> wrote:

> Hi
> 
> I have a rather large data frame (>7000 rows with 28 columns) which I want
> to sort by date. Below I have a example of the data frame. The Date column
> is called DT, is a factor and looks like this:
> 
> class(res.merge$DT)
> [1] "factor"
> head(res.merge$DT)
> [1] 17.3.2012 13:54:02 17.3.2012 14:00:07 17.3.2012 14:30:25 17.3.2012
> 15:01:15
> [5] 17.3.2012 15:32:14 17.3.2012 16:01:29
> 2530 Levels: 1.4.2012 00:00:52 1.4.2012 00:30:29 ... 9.5.2012 15:30:50
> 
> res.merge is the data frame unordered. Now I want to order the data frame
> with:
> 
> res.ordered<-res.merge[order(as.POSIXct(as.character(res.merge$DT),format="%d.%m.%Y
> %H:%M:%S")),]
> 
> This works in fact, however for some reason there are always two entires
> that go at the end of the data frame for no obvious reason (see below,
> 09.05.2012 ist the most recent date). And this is the case for different
> data.frames. The two entries at the end are always 25.3.2012 02:00:xx and
> 25.3.2012 02.30.xx.
> 
> Can anybody tell me what the problem is? Any help is most appreciated.
> 
> Best Benedikt
> 
> res.ordered[2545:2549,]
>                     DT Typ  NOD     Day_s DOW_s   Time_s     Long      Lat
> 2547  9.5.2012 14:30:56 GPS 1893  9.5.2012    We 14:30:00 7.452218 46.43579
> 2548  9.5.2012 15:02:09 GPS 1893  9.5.2012    We 15:00:35 7.451983 46.43583
> 2549  9.5.2012 15:30:50 GPS 1893  9.5.2012    We 15:30:00 7.451973 46.43597
> 1845 25.3.2012 02:00:18 GPS 1848 25.3.2012    So 02:00:01 7.454266 46.45414
> 1846 25.3.2012 02:30:16 GPS 1848 25.3.2012    So 02:30:00 7.454413 46.45437
>     Height TOF Status FO_GPS GPS_N AOT     Day_e DOW_e   Time_e   BV Temp 
> SOG
> 2547 1182.8   3      A      1   143  55  9.5.2012    We 14:30:56 3735   31
> 0.09
> 2548 1182.8   3      A      1   143  94  9.5.2012    We 15:02:09 3637   32
> 0.02
> 2549 1176.5   3      A      1   143  50  9.5.2012    We 15:30:50 3730   29
> 0.17
> 1845 1295.2   3      A      1   151  17 25.3.2012    So 02:00:18 3715    7
> 0.18
> 1846 1287.3   3      A      1   144  16 25.3.2012    So 02:30:16 3720    8
> 0.14
>     Heading  SAE  HAE BW_2 BW_3  X..
> 2547   24.90 3.81 9.47 3666 3625 9.08
> 2548    7.86 0.51 7.17 3593 3586 9.11
> 2549  344.72 2.86 4.10 3662 3623 9.12
> 1845  335.54 3.53 5.63 3618 3618 0.81
> 1846   75.37 5.44 8.96 3618 3618 0.81
> 
> --
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