[R] Date object

Rui Barradas
Sat, 21 Apr 2012 19:49:01 -0000

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]]
>
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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.


> 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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