[R] Zoo - bug ???
Gavin Simpson
gavin.simpson at ucl.ac.uk
Tue Jul 13 13:57:23 CEST 2010
On Tue, 2010-07-13 at 17:13 +0530, sayan dasgupta wrote:
> Hi folks,
>
> I am confused whether the following is a bug or it is fine
>
> Here is the explanation
>
> a <- zoo(c(NA,1:9),1:10)
>
> Now If I do
>
> rollapply(a,FUN=mean,width=3,align="right")
mean() has argument na.rm which defaults to FALSE. As such, if NA are in
the computation the mean is undefined and the answer will be NA. If you
pass na.rm = TRUE to rollapply, mean ignores the NA and works on the
remaining values:
> rollapply(a,FUN=mean,width=3,align="right", na.rm = TRUE)
3 4 5 6 7 8 9 10
1.5 2.0 3.0 4.0 5.0 6.0 7.0 8.0
HTH
G
>
> I get
> > rollapply(a,FUN=mean,width=3,align="right")
> 3 4 5 6 7 8 9 10
> NA NA NA NA NA NA NA NA
>
> But I shouldn't be getting NA right ? i.e for index 10 I should get
> (1/3)*(9+8+7)
>
> Similarly
>
> > rollapply(a,FUN=mean,width=3)
> 2 3 4 5 6 7 8 9
> NA NA NA NA NA NA NA NA
>
>
> Zoo version :
>
> > installed.packages()["zoo","Version"]
> [1] "1.6-3"
> >
>
>
> My machine details
>
> > sessionInfo()
> R version 2.10.1 (2009-12-14)
> i386-pc-intel32
>
> locale:
> [1] LC_COLLATE=English_India.1252 LC_CTYPE=English_India.1252
> LC_MONETARY=English_India.1252 LC_NUMERIC=C
> [5] LC_TIME=English_India.1252
>
> attached base packages:
> [1] stats graphics grDevices datasets utils methods base
>
> other attached packages:
> [1] zoo_1.6-3 rcom_2.2-1 rscproxy_1.3-1 Revobase_3.2.0
>
> loaded via a namespace (and not attached):
> [1] grid_2.10.1 lattice_0.18-3 tools_2.10.1
> >
>
> [[alternative HTML version deleted]]
>
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Dr. Gavin Simpson [t] +44 (0)20 7679 0522
ECRC, UCL Geography, [f] +44 (0)20 7679 0565
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