R help - Nov 2008 - inconsistency between timeSeries and zoo causing a problem with rbind

Dear R Users and maintainers of packages zoo and timeSeries,

I believe there is a recently introduced inconsistency between 
timeSeries and zoo which is causing a problem with rbind. I had 
previously reported that I was having problems with rbind in the 
following code:

library(zoo)
foo<-zoo(1,order.by=as.Date("2007-10-09"))
bar<-zoo(2,order.by=as.Date("2007-10-10"))
bar <- rbind(zoo(0, order.by = index(foo)[1]), bar)
bar

Gabor Grothendieck and Dieter Menne tried this code and wrote back 
saying it was working fine. I have also tried this in a fresh session 
and it works fine if the only package I load is zoo. It appears that the 
code fails if one simultaneously loads packages zoo and timeSeries

library(zoo)
library(timeSeries)
foo<-zoo(1,order.by=as.Date("2007-10-09"))
bar<-zoo(2,order.by=as.Date("2007-10-10"))
bar <- rbind(zoo(0, order.by = index(foo)[1]), bar)
bar
sessionInfo()

This leads to the error I had previously reported, please see below. I 
am R 2.8.0, zoo 1.5-4 and timeSeries 280.78.  I believe this is 
potentially a bug: I was not getting this issue even though I have been 
using zoo and timeSeries in the same session since the most recent 
updates to these packages.

Is this a bug ? If so, can it be corrected somehow ?

Thanks in advance,
Tolga

 > library(zoo)

Attaching package: 'zoo'


        The following object(s) are masked from package:base :

         as.Date.numeric

 > library(timeSeries)
Loading required package: timeDate

Attaching package: 'timeSeries'


        The following object(s) are masked from package:zoo :

         time<-

 > foo<-zoo(1,order.by=as.Date("2007-10-09"))
 > bar<-zoo(2,order.by=as.Date("2007-10-10"))
 > bar <- rbind(zoo(0, order.by = index(foo)[1]), bar)
Error in rep.int("", nrow(r)) : incorrect type for second argument 
<<<<<<<<< ERROR
 > bar
2007-10-10
         2
 > sessionInfo()
R version 2.8.0 (2008-10-20)
i386-pc-mingw32

locale:
LC_COLLATE=English_United Kingdom.1252;LC_CTYPE=English_United 
Kingdom.1252;LC_MONETARY=English_United 
Kingdom.1252;LC_NUMERIC=C;LC_TIME=English_United Kingdom.1252

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base    

other attached packages:
[1] timeSeries_280.78 timeDate_280.80   zoo_1.5-4       

loaded via a namespace (and not attached):
[1] grid_2.8.0      lattice_0.17-15
 >

On Sun, 16 Nov 2008, Tolga Uzuner wrote:
> I believe there is a recently introduced inconsistency between timeSeries
and
> zoo which is causing a problem with rbind. I had previously reported that I
> was having problems with rbind in the following code:
>
> library(zoo)
> foo<-zoo(1,order.by=as.Date("2007-10-09"))
> bar<-zoo(2,order.by=as.Date("2007-10-10"))
> bar <- rbind(zoo(0, order.by = index(foo)[1]), bar)
> bar
What happens is the following:
   - There is base:::rbind() and methods:::rbind(). The former is just
     an .Internal() call while the latter additionally does consistency
     checks. The consistency checks require that you can only rbind()
     if the result has a dimension.
   - base:::rbind() is usually found first, even if "methods" is
loaded.
     But if you load "timeSeries" this changes and methods:::rbind()
is
     found first. I haven't figured out why this happens but it does _not_
     for other S4 packages (such as "Matrix" for example).
   - Thus, if you rbind 1d zoo series, the result is also 1d and has no
     dimension. If "timeSeries" is loaded, methods:::rbind() is called
     which assumes a dimension and fails if there is none.

What should be done:
   - I'm not sure whether "timeSeries" can be changed so that
     base:::rbind() is still found first.
   - Maybe methods:::rbind() could be made more liberal so that it does
     not fail for 1d return values. Of course, one could argue that a row
     bind only makes sense if there are rows and columns. But, then again,
     maybe it is possible to allow other usages as well.
   - You can work around this as a user of zoo series, by calling c()
     instead of rbind() for 1d series, i.e.,
       c(foo, bar)
     always works with or without "timeSeries" attached. Moreover, c()
     even works for 2d zoo series.

hth,
Z