[R] Date_Time detected as Duplicated (but they are not!)

[Agustin Lobo]

and is it not possible to ignore savings time? My data are in UTC,
with no savings time changes
> delme = strptime(aur2009[,1], "%m/%d/%Y %H:%M",tz="UTC")
> any(duplicated(delme))
[1] TRUE

> delme = as.POSIXct(aur2009[,1], "%m/%d/%Y %H:%M",tz="UTC")
> any(duplicated(delme))
[1] TRUE

Agus

On Wed, May 18, 2011 at 8:55 AM, Michael Sumner <mdsumner at gmail.com> wrote:
> See under "Note" in ?strptime:
>    Remember that in most timezones some times do not occur and some
>      occur twice because of transitions to/from summer time.
>      ‘strptime’ does not validate such times (it does not assume a
>      specific timezone), but conversion by ‘as.POSIXct’) will do so.
>
>
>
> On Wed, May 18, 2011 at 3:53 PM, Agustin Lobo <Agustin.Lobo at ictja.csic.es>
> wrote:
>>
>> I have a problem with duplicated date_time stamps that I do not see as
>> duplicated.
>>
>> I read a file with observations taken every 30 minutes:
>>
>> >
>> > aur2009=read.csv(paste(datadir,"AUR_ECPP_2009.csv",sep="/"),sep=";",stringsAsFactors=F)
>> > aur2009[1:3,1:5]
>>      Date.Time E_filled E_filled_flag LE_filled LE_filled_flag
>> 1 1/1/2009 0:00        0           NaN      5.86            NaN
>> 2 1/1/2009 0:30        0           NaN      5.05            NaN
>> 3 1/1/2009 1:00        0           NaN      5.56            NaN
>>
>> > delme = strptime(aur2009[,1], "%m/%d/%Y %H:%M")
>> > aur2009[,1]=as.POSIXct(delme)
>>            Date.Time E_filled E_filled_flag LE_filled LE_filled_flag
>> 1 2009-01-01 00:00:00        0           NaN      5.86            NaN
>> 2 2009-01-01 00:30:00        0           NaN      5.05            NaN
>> 3 2009-01-01 01:00:00        0           NaN      5.56            NaN
>>
>> > aur2009ts = ts(aur2009)
>> > row.names(aur2009ts) = as.character(delme)
>> > aur2009ts[1:3,1:5]
>>                     Date.Time E_filled E_filled_flag LE_filled
>> LE_filled_flag
>> 2009-01-01 00:00:00 1230764400        0           NaN      5.86
>>  NaN
>> 2009-01-01 00:30:00 1230766200        0           NaN      5.05
>>  NaN
>> 2009-01-01 01:00:00 1230768000        0           NaN      5.56
>>  NaN
>>
>> Then:
>> > aur2009z = zoo(aur2009[,2:12],as.POSIXct(delme))
>> Warning message:
>> In zoo(aur2009[, 2:12], as.POSIXct(delme)) :
>>  some methods for “zoo” objects do not work if the index entries in
>> ‘order.by’ are not unique
>>
>> So I investigate:
>> > any(duplicated(aur2009ts[,1]))
>> [1] TRUE
>>
>> > aur2009ts[(duplicated(aur2009ts[,1])),1:5]
>>                     Date.Time E_filled E_filled_flag LE_filled
>> LE_filled_flag
>> 2009-03-29 02:00:00 1238284800        0           NaN       1.2
>>  NaN
>> 2009-03-29 02:30:00 1238286600        0           NaN       1.2
>>  NaN
>>
>> But note the surprise:
>> > aur2009ts[aur2009ts[,1]==1238284800,1:5]
>>                     Date.Time E_filled E_filled_flag LE_filled
>> LE_filled_flag
>> 2009-03-29 01:00:00 1238284800        0           NaN     -0.58
>>  NaN
>> 2009-03-29 02:00:00 1238284800        0           NaN      1.20
>>  NaN
>> > aur2009ts[aur2009ts[,1]==1238286600,1:5]
>>                     Date.Time E_filled E_filled_flag LE_filled
>> LE_filled_flag
>> 2009-03-29 01:30:00 1238286600        0           NaN     -0.34
>>  NaN
>> 2009-03-29 02:30:00 1238286600        0           NaN      1.20
>>  NaN
>>
>> The dates detected as duplicated are actually different times that got
>> the same value in the ts version of the object!
>> What am I doing wrong? They are all observations every 30min, why are
>> these 2 encoded as the
>> same time?
>>
>> Any help appreciated
>>
>> Agus
>>
>> ______________________________________________
>> 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.
>
>
>
> --
> Michael Sumner
> Institute for Marine and Antarctic Studies, University of Tasmania
> Hobart, Australia
> e-mail: mdsumner at gmail.com
>