[R] How can I declare an empty zoo object?

[R. Michael Weylandt]

On Tue, Jul 31, 2012 at 2:40 AM, jpm miao <miaojpm at gmail.com> wrote:
> Hi Michael,
>
>    1. I try this
>
>         xzoo <- zoo()
>
>        and it does work. OK, I will read the reference you provide to find
> out why not to do so
>
>     2. How can I create an array of zoo objects?

I'm not quite sure what you mean by an array of zoo objects: the
"data" of the zoo object can be a matrix so you can have rows and
columns and all that. Alternatively you can stick the different zoo
objects in a list (as you can with any R object)

>
>     3. Do you mean by "R's wisest virgil" Pat Burns' R Inferno?

Well, Pat Burns himself really -- see, e.g.,
http://www.brown.edu/Departments/Italian_Studies/LD/numbers/04/hollander.html
or less technically, http://www.shmoop.com/inferno/virgil.html.

Michael

>
> To Arun:
>
>     Even when indices (dates) of two zoo object don't match, I can cbind
> them. It works for me!
>
>     Thanks,
>
> Miao
>
>
>
> 2012/7/31 R. Michael Weylandt <michael.weylandt at gmail.com>
>>
>> On Mon, Jul 30, 2012 at 11:18 PM, jpm miao <miaojpm at gmail.com> wrote:
>> > Hi,
>> >
>> >    I let xzoo be an empty  object:
>> >
>> >> xzoo<-{}
>>
>> This sounds like the start of a bad idea....
>>
>>
>> >
>> >
>> >    and I have an existing zoo object x1zoo_f. I would like to combine
>> > the two to make a new zoo object, and continue doing so in a loop,
>> > which is not shown here. However, when I type
>> >
>> >
>> >> xzoo<-cbind(xzoo, x1zoo_f)
>>
>> Yep: the real answer is "don't do that." Since R is
>> copy-on-write+pass-by-reference and a few other nice things, this will
>> be painfully gut-wrenchingly paint-dryingly slow :-) Much better is to
>> make all your "x1zoo_f" objects and cbind them at once.
>>
>> The perils of this idea and the appropriate fixings thereof have been
>> discussed here there and everywhere, but I think Pat Burn's
>> presentation in "the R Inferno" is the best (and certainly the most
>> fun) -- it's a worthwhile read and, perhaps an even higher compliment,
>> a worthwhile re-read.
>>
>> Based on my rough memories of your recent posts, you won't understand
>> it all in the first pass (few do -- I certainly don't), but over time
>> you'll gain immensely from the work of one of R's wisest Virgils.
>>
>>
>> >
>> >
>> >    An error message emerges
>> >
>> >
>> > Error in zoo(structure(x, dim = dim(x)), index(x), ...) :
>> >   “x” : attempt to define invalid zoo object
>> >
>> >
>> >    Is there any way to define an empty zoo object?
>> >
>>
>> For completeness,
>>
>> xzoo <- zoo()
>>
>> But like I said: don't do that.
>>
>> Cheers,
>> Michael
>>
>>
>> >
>> >   Thanks,
>> >
>> >
>> > Miao
>> >
>> >         [[alternative HTML version deleted]]
>> >
>> >
>> > ______________________________________________
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>> > https://stat.ethz.ch/mailman/listinfo/r-help
>> > PLEASE do read the posting guide
>> > http://www.R-project.org/posting-guide.html
>> > and provide commented, minimal, self-contained, reproducible code.
>> >
>
>