On Mar 14, 2011, at 6:36 AM, Allan Engelhardt wrote:
On 14/03/11 02:00, Raoni Rosa Rodrigues wrote:
Hello R Help,
I'm working in a project with a software that register date and
time data in serial time format. This format is used by excel, for
exemple. In this format, 40597.3911423958 is 2011/2/23 09:23:15.
Not on my system,
Because ... There is a reasonably well understood MS bug in how it
handles the non-existent 1900-02-29. (It _still_ accepts that as a
valid date and calls it 60. I just re-demonstrated this amazingly
persistent bug behavior on the Mac Excel 2011 variant. )
http://finzi.psych.upenn.edu/R/library/cxxPack/html/serialNumber.html
http://finzi.psych.upenn.edu/R/Rhelp02/archive/22942.html
(I don't think Gabor's speculation regarding the migration from
Windows Excel to Mac Excel is possibly correct since Excel was
introduced on the Mac years before Windows was even a crash-prone GUI
on top of MS-DOS. The claim on one MS page is that the bug originated
in Lotus 1-2-3 and was emulated by Multiplan for compatibility. )
--
David.
but this should get you going:
( a<- as.POSIXct("2011-02-23 09:23:15.00001", tz="GMT") )
# [1] "2011-02-23 09:23:15 GMT"
( b<- difftime(a, ISOdatetime(1900,1,1,0,0,0), tz="GMT",
units="days") )
# Time difference of 40595.39 days
as.double(b)
# [1] 40595.39
options("digits.secs" = 6)
ISOdatetime(1900, 1, 1, 0, 0, 0) + 40597.3911423958*60*60*24 # TZ
dependent
[1] "2011-02-25 09:23:14.702997 GMT"
Hope this helps a little.
Allan
First part is number os days since 1900/1/1, and second part is a
fraction of a day.
I need to make this transformation in R, and use it to make some
algebrian operations. I found that function 'serialNumber' of
package 'cxxPack' transform a as.data class object in this format,
but without time fraction. But I can't find nothing to do the
inverse way, transform serial date format in a POSIX class, for
exemple.
Since now, thanks for your time and atention.
All best,
Raoni
Associate Researcher
Fish Passage Center
UFMG, Brazil.
"Fica proibido o uso da palavra liberdade,
a qual será suprimida dos dicionários
e do pântano enganoso das bocas.
A partir deste instante
a liberdade será algo vivo e transparente
como um fogo ou um rio,
e a sua morada será sempre
o coração do homem."
(Thiago de Mello)
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______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
West Hartford, CT
______________________________________________
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