[R] inconsistency between timeSeries and zoo causing a problem with rbind

Tolga Uzuner tolga.uzuner at gmail.com
Sun Nov 16 18:22:19 CET 2008

Dear Achim,
Many thanks, that is very helpful.

Achim Zeileis wrote:
> 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

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