Sklyar, Oleg (London)
2008-Oct-14 16:12 UTC
[Rd] POSIXlt getting sec element at 60 when converting from POSIXct
In some cases rounding problems lead to creation of logically incorrect
times in POSIXlt when converting from POSIXct.
## everything works fine for the following values:
x = c(1223972160.00000, 1223982660.00000, 1223994660.0000)
## adding 0s for the epoch
x = x + as.POSIXct("1970-01-01 00:00") -
as.numeric(as.POSIXct("1970-01-01 00:00"))
x
## [1] "2008-10-14 09:16:00 BST" "2008-10-14 12:11:00 BST"
## [3] "2008-10-14 15:31:00 BST"
Now, numbers that look the same but originate from some calculations
lead to the following weirdness in POSIXlt. Sorry you will not be able
to reproduce as it is impossible to reproduce the same rounding:
> as.character(as.numeric(t1))
[1] "1223972160.00000" "1223982660.00000"
"1223994660.00000"> class(t1)
[1] "POSIXt" "POSIXct"
## here we get a second less due to rounding errors somewhere, not too
bad> t1
[1] "2008-10-14 09:15:59 BST" "2008-10-14 12:10:59 BST"
[3] "2008-10-14 15:30:59 BST"> t2 = as.POSIXlt(t1)
> t2
[1] "2008-10-14 09:15:59 BST" "2008-10-14 12:10:59 BST"
[3] "2008-10-14 15:30:59 BST"
## however here we do get a real problem> t2$sec
[1] 60 60 60
## and here as well> format(t2, "%Y-%m-%d %H:%M:%OS3")
[1] "2008-10-14 09:15:60.000" "2008-10-14 12:10:60.000"
[3] "2008-10-14 15:30:60.000"> format(t1, "%Y-%m-%d %H:%M:%OS3")
[1] "2008-10-14 09:15:60.000" "2008-10-14 12:10:60.000"
[3] "2008-10-14 15:30:60.000"
Everything is back to normal with applying round (we are anyway limited
to 15 digits):> t3 = round(as.numeric(t1),5) + .origin
> t3
[1] "2008-10-14 09:16:00 BST" "2008-10-14 12:11:00 BST"
[3] "2008-10-14 15:31:00 BST"
> sessionInfo()
R version 2.9.0 Under development (unstable) (2008-09-30 r46585)
x86_64-unknown-linux-gnu
locale:
C
attached base packages:
[1] splines stats graphics utils datasets grDevices methods
[8] base
other attached packages:
[1] AHLFinance_0.1.54 AHLDBConn_0.2.3 ROracle_0.5-9 DBI_0.2-4
[5] RODBC_1.2-3 AHLNagLib_0.1.3 AHLCalendar_0.2.59
AHLBase_0.1.25
loaded via a namespace (and not attached):
[1] tools_2.9.0
Dr Oleg Sklyar
Research Technologist
AHL / Man Investments Ltd
+44 (0)20 7144 3107
osklyar at maninvestments.co
**********************************************************************
The contents of this email are for the named addressees ...{{dropped:19}}
Prof Brian Ripley
2008-Oct-15 03:10 UTC
[Rd] POSIXlt getting sec element at 60 when converting from POSIXct
As you say, not reproducible. Any chance that you could put a save() file containing t1 somewhere we can get it? On Tue, 14 Oct 2008, Sklyar, Oleg (London) wrote:> In some cases rounding problems lead to creation of logically incorrect > times in POSIXlt when converting from POSIXct. > > ## everything works fine for the following values: > x = c(1223972160.00000, 1223982660.00000, 1223994660.0000) > ## adding 0s for the epoch > x = x + as.POSIXct("1970-01-01 00:00") - > as.numeric(as.POSIXct("1970-01-01 00:00")) > x > ## [1] "2008-10-14 09:16:00 BST" "2008-10-14 12:11:00 BST" > ## [3] "2008-10-14 15:31:00 BST" > > Now, numbers that look the same but originate from some calculations > lead to the following weirdness in POSIXlt. Sorry you will not be able > to reproduce as it is impossible to reproduce the same rounding: > >> as.character(as.numeric(t1)) > [1] "1223972160.00000" "1223982660.00000" "1223994660.00000" >> class(t1) > [1] "POSIXt" "POSIXct" > ## here we get a second less due to rounding errors somewhere, not too > bad >> t1 > [1] "2008-10-14 09:15:59 BST" "2008-10-14 12:10:59 BST" > [3] "2008-10-14 15:30:59 BST" >> t2 = as.POSIXlt(t1) >> t2 > [1] "2008-10-14 09:15:59 BST" "2008-10-14 12:10:59 BST" > [3] "2008-10-14 15:30:59 BST" > > ## however here we do get a real problem >> t2$sec > [1] 60 60 60 > ## and here as well >> format(t2, "%Y-%m-%d %H:%M:%OS3") > [1] "2008-10-14 09:15:60.000" "2008-10-14 12:10:60.000" > [3] "2008-10-14 15:30:60.000" >> format(t1, "%Y-%m-%d %H:%M:%OS3") > [1] "2008-10-14 09:15:60.000" "2008-10-14 12:10:60.000" > [3] "2008-10-14 15:30:60.000" > > Everything is back to normal with applying round (we are anyway limited > to 15 digits): >> t3 = round(as.numeric(t1),5) + .origin >> t3 > [1] "2008-10-14 09:16:00 BST" "2008-10-14 12:11:00 BST" > [3] "2008-10-14 15:31:00 BST" > >> sessionInfo() > R version 2.9.0 Under development (unstable) (2008-09-30 r46585) > x86_64-unknown-linux-gnu > > locale: > C > > attached base packages: > [1] splines stats graphics utils datasets grDevices methods > > [8] base > > other attached packages: > [1] AHLFinance_0.1.54 AHLDBConn_0.2.3 ROracle_0.5-9 DBI_0.2-4 > > [5] RODBC_1.2-3 AHLNagLib_0.1.3 AHLCalendar_0.2.59 > AHLBase_0.1.25 > > loaded via a namespace (and not attached): > [1] tools_2.9.0 > > Dr Oleg Sklyar > Research Technologist > AHL / Man Investments Ltd > +44 (0)20 7144 3107 > osklyar at maninvestments.co > > ********************************************************************** > The contents of this email are for the named addressees ...{{dropped:19}} > > ______________________________________________ > R-devel at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel >-- Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595