R help - Jul 2012 - How can I declare an empty zoo object?

Hi,

   I let xzoo be an empty  object:
> xzoo<-{}

   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)

   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?


  Thanks,


Miao

	[[alternative HTML version deleted]]

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]]
>
>
> ______________________________________________
> R-help at r-project.org mailing list
> 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.
>

Hi,

When you cbind two zoo objects, I guess the index should match, otherwise it
gives warning messages:

x1zoo_f<-zoo(rnorm(5,25),c(1,5,10,15,9))
xzoo<-zoo(c(5,9,10,15),c(1,5,9,10,15))
cbind(xzoo,x1zoo_f)
?? xzoo? x1zoo_f
1???? 5 24.85877
5???? 9 25.09264
9??? 10 25.79896
10?? 15 26.70625
15??? 5 24.63533
#If index is different
xzoo<-zoo(c(5,9,10,15,25), 1:5)
?cbind(xzoo,x1zoo_f)
?? xzoo? x1zoo_f
1???? 5 24.85877
2???? 9?????? NA
3??? 10?????? NA
4??? 15?????? NA
5??? 25 25.09264
9??? NA 25.79896
10?? NA 26.70625
15?? NA 24.63533
Warning message:
In merge.zoo(..., all = all, fill = fill, suffixes = suffixes, retclass =
"zoo",? :
? Index vectors are of different classes: integer numeric
######## now, with empty zoo object with same index
xzoo<-zoo(,c(1,5,9,10,15))
?str(xzoo)
?zoo? series (without observations)
?cbind(xzoo,x1zoo_f)
??? x1zoo_f
1? 24.85877
5? 25.09264
9? 25.79896
10 26.70625
15 24.63533

A.K.




From: jpm miao <miaojpm at gmail.com>

To: r-help <r-help at r-project.org>
Cc: 
Sent: Tuesday, July 31, 2012 12:18 AM
Subject: [R] How can I declare an empty zoo object?

Hi,

?  I let xzoo be an empty? object:
> xzoo<-{}

?  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)

?  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?


? Thanks,


Miao

??? [[alternative HTML version deleted]]


______________________________________________
R-help at r-project.org mailing list
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.