Date_Time detected as Duplicated (but they are not!)

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
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

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--
Michael Sumner
Institute for Marine and Antarctic Studies, University of Tasmania
Hobart, Australia
e-mail: mdsumner at gmail.com

Date_Time detected as Duplicated (but they are not!)

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