R help - Jun 2013 - Need help on window() function of the 'zoo' package

Hi,
 
I observed that if I use window() function available with the 'zoo'
package to extract a portion of my times series and if that time series data is
stored in some 'zoo' object with only 1 column, then the resulting zoo
object is becoming vector.
 
Here is my observation:
 
> library(zoo)
> Dat <- matrix(1:3, nc = 1)
> Dat
     [,1]
[1,]    1
[2,]    2
[3,]    3
> Dat_zoo <- zooreg(Dat, start = as.Date("2001-01-01"),
frequency = 1)
> Dat_zoo
            
2001-01-01 1
2001-01-02 2
2001-01-03 3
> window(Dat_zoo, start = as.Date("2001-01-02"))   ### why it is
becoming vector? I want to retain it as matrix only
2001-01-02 2001-01-03 
         2          3 
 
Here you can see that, originally my 'Dat_zoo ' object was basically a
matrix. However once I use window() function, it became vector.
 
Is there any possibility to retain the shape of the original object,
particularly if that object is matrix with 1 column?
 
Thank you very much for your help.
	[[alternative HTML version deleted]]

Hello,

Actually, Dat_zoo is not a matrix, it is an object of classes "zooreg"
and "zoo", with a dim attribute:

class(Dat_zoo)
dim(Dat_zoo)

And the output of window() is of the same classes but without a dim 
attribute:

wnd <- window(Dat_zoo, start = as.Date("2001-01-02"))
class(wnd)
dim(wnd)  # NULL


You can set the dim attribute manually like this:

dim(wnd) <- c(length(wnd), 1)


Hope this helps,

Rui Barradas

Em 08-06-2013 22:02, Ron Michael escreveu:
> Hi,
>
> I observed that if I use window() function available with the 'zoo'
package to extract a portion of my times series and if that time series data is
stored in some 'zoo' object with only 1 column, then the resulting zoo
object is becoming vector.
>
> Here is my observation:
>
>> library(zoo)
>> Dat <- matrix(1:3, nc = 1)
>> Dat
>       [,1]
> [1,]    1
> [2,]    2
> [3,]    3
>> Dat_zoo <- zooreg(Dat, start = as.Date("2001-01-01"),
frequency = 1)
>> Dat_zoo
>
> 2001-01-01 1
> 2001-01-02 2
> 2001-01-03 3
>> window(Dat_zoo, start = as.Date("2001-01-02"))   ### why it
is becoming vector? I want to retain it as matrix only
> 2001-01-02 2001-01-03
>           2          3
>
> Here you can see that, originally my 'Dat_zoo ' object was
basically a matrix. However once I use window() function, it became vector.
>
> Is there any possibility to retain the shape of the original object,
particularly if that object is matrix with 1 column?
>
> Thank you very much for your help.
> 	[[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.
>