On 2/03/2011 12:31 p.m., Nordlund, Dan (DSHS/RDA) wrote:
-----Original Message----- From: r-help-boun...@r-project.org
[mailto:r-help-bounces@r- project.org] On Behalf Of Luis Felipe
Parra Sent: Tuesday, March 01, 2011 3:07 PM To: r-help Subject: [R]
Difference in numeric Dates between Excel and R
Hello. I am using some dates I read in excel in R. I know the
excel origin is supposed to be 1900-1-1. But when I used as.Date
with origin=1900-1- 1 the dates that R reported me where two days
ahead than the ones I read from Excel. I noticed that when I did in
R the following:
as.Date("2011-3-4")-as.Date("1900-1-1")
Time difference of 40604 days
but if I do the same operation in Excel the answer is 40605. Does
anybody know what can be going on?
I think so. It is a known problem that Excel thinks 1900 was a leap
year, but it was not. So Excel counts an extra day (for nonexistent
Feb 29, 1900). In addition, Excel considers "1900-01-01" as day 1,
not day 0.
Hope this is helpful,
Dan
An explanation which seems reasonably authoritative is given here:
http://www.cpearson.com/excel/datetime.htm
David Scott
Daniel J. Nordlund Washington State Department of Social and Health
Services Planning, Performance, and Accountability Research and Data
Analysis Division Olympia, WA 98504-5204
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--
_________________________________________________________________
David Scott Department of Statistics
The University of Auckland, PB 92019
Auckland 1142, NEW ZEALAND
Phone: +64 9 923 5055, or +64 9 373 7599 ext 85055
Email: d.sc...@auckland.ac.nz, Fax: +64 9 373 7018
Director of Consulting, Department of Statistics
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