[R] date operations

[jim holtman]

'str' is your friend.  Look at the results:

> alpha2=as.Date("2008-12-21")
> alpha1=as.Date("2008-12-21")-as.Date("2008-10-26")
> alpha1
Time difference of 56 days
> alpha2
[1] "2008-12-21"
> alpha1+alpha2
Time difference of 14290 days
Warning message:
Incompatible methods ("Ops.difftime", "+.Date") for "+"
> str(alpha1)
Class 'difftime'  atomic [1:1] 56
  ..- attr(*, "units")= chr "days"
> str(alpha2)
Class 'Date'  num 14234
>

alpha1 is not of the Date class.

On Tue, Dec 2, 2008 at 4:10 PM, Christophe Dutang <dutangc at gmail.com> wrote:
> Hi all,
>
> I'm dealing with dates in R (2.7.2), but some basic operations raise a
> warning.
>
> Incompatible methods ("+.Date", "Ops.difftime") for "+"
>
> I saw this topic in this mailing list, but I do not understand what to
> do...
>
> cf. https://stat.ethz.ch/pipermail/r-help/2008-June/165842.html
>
> Do I have to convert Dates to numeric?
>
> Thanks in advance
>
> Christophe
>
> PS : R script used
>
> alpha2=as.Date("2008-12-21")
> alpha1=as.Date("2008-12-21")-as.Date("2008-10-26")
> alpha1
> alpha2
> alpha1+alpha2
>
>
>        [[alternative HTML version deleted]]
>
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-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?