On Mar 15, 2011, at 2:17 AM, Raoni Rosa Rodrigues wrote:
Hello Mr. Allan and Mr. David!
Thanks very much for your time and lessons.
Works pretty well, Mr. Allan, specially after Mr. David explanation
(and the 2 days-bug correction).
Just a curious behavior of data tranformation: the R-transformation
date was 2min and 20s late compared with excel 2007 time. Did you
know why?
I do not. One hypothesis might be that it relates to different
treatment of the accumulation of leap-seconds:
http://en.wikipedia.org/wiki/Leap_second
Just a theory.
--
David.
Attached a file with more than 1800 date-time values, that I used to
compare data. I ran this code on R
Data = function (x){
c (ISOdatetime (1900, 1, 1, 0, 0, 0) + ((x-2)*60*60*24))
}
and pasted result on excel where I compared with date time
personalized format (YYYY/MM/DD HH:MM:SS) of excel of original file.
When I used a corrected code
Data = function (x){
c (ISOdatetime (1900, 1, 1, 0, 2, 20) + ((x-2)*60*60*24))
}
worked pretty well.
Thanks again!
All best,
Raoni
--- Em seg, 14/3/11, David Winsemius <dwinsem...@comcast.net>
escreveu:
De: David Winsemius <dwinsem...@comcast.net>
Assunto: Re: [R] Serial Date
Para: "Allan Engelhardt" <all...@cybaea.com>
Cc: "Raoni Rosa Rodrigues" <raonir...@yahoo.com.br>, "R Help" <r-help@r-project.org
>
Data: Segunda-feira, 14 de Março de 2011, 13:00
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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______________________________________________
R-help@r-project.org mailing list
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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
<DateTime.txt>
David Winsemius, MD
West Hartford, CT
______________________________________________
R-help@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.
