R help - Apr 2010 - Strange zoo behaviour, possible bug?

Hi all,

I bumped into this awkward zoo behaviour. I'd be half tempted to call it a
bug, what do you think? It's annoying to work around it :( I wonder if this
was the behaviour of older zoo versions, I can't remember coming across this
sort of thing...
> version
               _
platform       i386-pc-solaris2.10
arch           i386
os             solaris2.10
system         i386, solaris2.10
status
major          2
minor          10.1
year           2009
month          12
day            14
svn rev        50720
language       R
version.string R version 2.10.1 (2009-12-14)
> packageDescription("zoo")
Package: zoo
Version: 1.6-2
Date: 2009-11-23
>t1 = zoo(-100,   as.POSIXct("2009-12-31")+(2:10)*60*60*24)
>t2 = zoo(matrix(0), index(t1)[1]-1)
>colnames(t1)="test"
>colnames(t2) = colnames(t1)
> t1
2010-01-02 2010-01-03 2010-01-04 2010-01-05 2010-01-06 2010-01-07 2010-01-08
      -100       -100       -100       -100       -100       -100       -100
2010-01-09 2010-01-10
      -100       -100
> t2
2010-01-01 23:59:59 0
>rbind(t1,t2)
2010-01-01 23:59:59    0
2010-01-02 00:00:00 -100
2010-01-03 00:00:00    0
2010-01-04 00:00:00 -100
2010-01-05 00:00:00    0
2010-01-06 00:00:00 -100
2010-01-07 00:00:00    0
2010-01-08 00:00:00 -100
2010-01-09 00:00:00    0
2010-01-10 00:00:00 -100
Warning message:
In rbind(c(-100, -100, -100, -100, -100, -100, -100, -100, -100),  :
  number of columns of result is not a multiple of vector length (arg 1)
>rbind(as.xts(t1),as.xts(t2))
                    [,1]
2010-01-01 23:59:59    0
2010-01-02 00:00:00 -100
2010-01-03 00:00:00 -100
2010-01-04 00:00:00 -100
2010-01-05 00:00:00 -100
2010-01-06 00:00:00 -100
2010-01-07 00:00:00 -100
2010-01-08 00:00:00 -100
2010-01-09 00:00:00 -100
2010-01-10 00:00:00 -100

And also:
> t1 = zoo(matrix(-100,ncol=1),  
as.POSIXct("2009-12-31")+(2:10)*60*60*24)
> rbind(t1,t2)
2010-01-01 23:59:59    0
2010-01-02 00:00:00 -100
2010-01-03 00:00:00 -100
2010-01-04 00:00:00 -100
2010-01-05 00:00:00 -100
2010-01-06 00:00:00 -100
2010-01-07 00:00:00 -100
2010-01-08 00:00:00 -100
2010-01-09 00:00:00 -100
2010-01-10 00:00:00 -100

Cheers,

//Giuseppe

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This email and any files transmitted with it are confide...{{dropped:14}}

On Wed, 28 Apr 2010, Giuseppe Milicia wrote:
> Hi all,
>
> I bumped into this awkward zoo behaviour. I'd be half tempted to call
it
> a bug, what do you think?
The situation could probably be improved on the zoo side but the source of 
the problem is clearly user error.
> It's annoying to work around it :(
You would just have to use it appropriately :-)
In addition to that, we can maybe improve warnings/errors.
>> t1 = zoo(-100,   as.POSIXct("2009-12-31")+(2:10)*60*60*24)
>> t2 = zoo(matrix(0), index(t1)[1]-1)
Just to be clear: t1 is a vector, t2 is a one-column matrix.
>> colnames(t1)="test"
This doesn't work and it tells you that it doesn't work.

Error in `colnames<-`(`*tmp*`, value = "test") :
   attempt to set colnames on object with less than two dimensions

If you want it to work, then the data in the time series should be a 
matrix (as you showed at the bottom of your post), e.g.:

t1 <- zoo(as.matrix(coredata(t1)), time(t1))
colnames(t1) <- "test"

If you do that, everything else will work as expected.
>> rbind(t1,t2)
>
> 2010-01-01 23:59:59    0
> 2010-01-02 00:00:00 -100
> 2010-01-03 00:00:00    0
> 2010-01-04 00:00:00 -100
> 2010-01-05 00:00:00    0
> 2010-01-06 00:00:00 -100
> 2010-01-07 00:00:00    0
> 2010-01-08 00:00:00 -100
> 2010-01-09 00:00:00    0
> 2010-01-10 00:00:00 -100
> Warning message:
> In rbind(c(-100, -100, -100, -100, -100, -100, -100, -100, -100),  :
>  number of columns of result is not a multiple of vector length (arg 1)
Yes, this is not nice, but it does warn you that something went wrong!
>> rbind(as.xts(t1),as.xts(t2))
"xts" stores everything internally as a matrix, hence there cannot be
a
confusion between vectors and matrices.

I'll have a look whether we can throw a better warning or maybe handle the 
border case of rbinding a vector with a one-column matrix.

Best,
Z