[R] Ordeing Zoo object

[Achim Zeileis]

On Tue, 8 Dec 2009, Bogaso wrote:

>
> Hi all, I would like to ask how to order a Zoo object? Consider following
> code
>
>> dat <- zooreg(rnorm(5), as.yearmon(as.Date("2001-01-01")), frequency=12)
>> dat
>  Jan 2001   Feb 2001   Mar 2001   Apr 2001   May 2001
> -0.8916124 -0.4516505  1.1305884 -1.4881309  0.3703734
>
> Here I want to order from last to 1st i.e. from May to Jan. So I used
> following code :
>
>> dat[5:1]
>  Jan 2001   Feb 2001   Mar 2001   Apr 2001   May 2001
> -0.8916124 -0.4516505  1.1305884 -1.4881309  0.3703734
>
> Therefore I am not getting what I desired. If someone points out the correct
> code I would be grateful.

The zoo object itself is always ordered by time. So it takes the 
observations you specified (5:1) and orders them by time again (so you get 
1:5). You need to extract the data without the time index and then proceed 
as usual:

   sort(coredata(dat))
or
   coredata(dat)[5:1]
etc.
Z

> Thanks,
> -- 
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