On Apr 21, 2012, at 3:49 PM, Rui Barradas wrote:
Hello,
Veerappa Chetty wrote
HI,
I have to work with data objects. I have trouble. I would like to
convert
date to a integer of Julian dates omitting hours, minutes etc. I
tried as.
Date and also as.POSIXlt, ct etc.
Please help me to compute the following difference. I get an "NA" for
output.
1/14/2006 0:00:00 AM -1/9/2006 0:00:00 AM
Thanks.
Chetty
--
Professor of Family Medicine
Boston University
Tel: 617-414-6221, Fax:617-414-3345
emails: chettyvk@,vchetty@
[[alternative HTML version deleted]]
f-contained, reproducible code.
Maybe this is system dependent, but with me, unlike what the help for
'strptime' says,
the format character 'H' can be used with the am/pm indicator even
if 'p'
is present.
It will not throw an error but it does ignore the am/pm indicator when
%H is used.
> x <- c("1/14/2006 12:00:00 AM", "1/9/2006 2:00:00 PM")
> d <- strptime(x, format ="%m/%d/%Y %H:%M:%S %p")
> d
[1] "2006-01-14 12:00:00" "2006-01-09 02:00:00"
--
David.
x <- c("1/14/2006 0:00:00 AM", "1/9/2006 0:00:00 AM")
# With '%p' in format string
d <- strptime(x, format ="%m/%d/%Y %H:%M:%S %p")
d[1] - d[2]
Time difference of 5 days
# Without '%p'
d <- strptime(x, format ="%m/%d/%Y %H:%M:%S")
d[1] - d[2]
Time difference of 5 days
sessionInfo()
R version 2.14.1 (2011-12-22)
Platform: x86_64-pc-mingw32/x64 (64-bit)
locale:
[1] LC_COLLATE=Portuguese_Portugal.1252
LC_CTYPE=Portuguese_Portugal.1252
[3] LC_MONETARY=Portuguese_Portugal.1252 LC_NUMERIC=C
[5] LC_TIME=Portuguese_Portugal.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
loaded via a namespace (and not attached):
[1] tools_2.14.1
And the minus operator works as expected.
Hope this helps,
Rui Barradas
--
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