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

[arun]

Hi,

#Without indices

 xzoo<-zoo()
 x1zoo_f<-zoo(1:10,)
 cbind(xzoo,x1zoo_f)
   x1zoo_f
1        1
2        2
3        3
4        4
5        5
6        6
7        7
8        8
9        9
10      10


#With indices on one
x1zoo_f<-zoo(1:5,1:10)
> cbind(xzoo,x1zoo_f)
   x1zoo_f
1        1
2        2
3        3
4        4
5        5
6        1
7        2
8        3
9        4
10       5

#with a different index.  Here, I get warning message.

 x1zoo_f<-zoo(1:5,c(5,6,8,11,13))
> cbind(xzoo,x1zoo_f)
   x1zoo_f
5        1
6        2
8        3
11       4
13       5
Warning message:
In merge.zoo(..., all = all, fill = fill, suffixes = suffixes, retclass = "zoo",  :
  Index vectors are of different classes: integer numeric


I am using R 2.15.  Don't know if you get warnings or not.
A.K.

________________________________
From: jpm miao <miaojpm at gmail.com>
To: R. Michael Weylandt <michael.weylandt at gmail.com> 
Cc: r-help <r-help at r-project.org>; smartpink111 at yahoo.com 
Sent: Tuesday, July 31, 2012 3:40 AM
Subject: Re: [R] How can I declare an empty zoo object?


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? 

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

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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>>
>