[R] Strange zoo behaviour, possible bug?

[Gabor Grothendieck]

I am not sure what the general case is here for you but here is a
kludge that works in this case:

t1 <- zoo(-100,   as.POSIXct("2009-12-31")+(2:10)*60*60*24)
t2 <- zoo(matrix(0), index(t1)[1]-1)

m <- merge(t1, t2, fill = 0)
m[,1] + m[,2]

By the way, the times in the above are really dates so "Date" class
may be more appropriate depending on what the real problem this is
taken from is.


On Wed, Apr 28, 2010 at 11:46 AM, Giuseppe Milicia
<Giuseppe.Milicia at makoglobal.com> wrote:
> Hi there,
>
> thanks for the reply. I agree that it's essentially a user error.
>
> I was really wondering whether the behaviour has changed from past version of zoo and whether it'd be worth to handle this case in a ad-hoc manner. I'm using old code and I was a bit surprised I didn't bump on this earlier...
>
> I have a function which can take as input zoo object whose coredata is either a matrix or a vector, to do that I'll have to handle the two cases slightly different. Not a bit deal, but kind of inelegant.
>
> Cheers,
>
> //Giuseppe
>
> ________________________________________
> From: Achim Zeileis [Achim.Zeileis at uibk.ac.at]
> Sent: 28 April 2010 16:25
> To: Giuseppe Milicia
> Cc: r-help at r-project.org
> Subject: Re: [R] Strange zoo behaviour, possible bug?
>
> 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
>
>
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