[R] Zoo - bug ???

[Joshua Ulrich]

Hi Christian,

On Tue, Nov 30, 2010 at 8:22 AM, clangkamp <christian.langkamp at gmxpro.de> wrote:
>
> I am not sure whether this is 100 % related, but I also get some unexpected
> behaviour with NA and rollapply:
> In the following example I would expect in Line 3 to see a 1 instead of an
> NA (mean out of [1, NA, NA]
> What do you think ?
>

I'm confused.  Why do you expect the 3rd element to have a non-NA
value when you've specified width=4?  The first 3 elements will be
missing (or NA if na.pad=TRUE) when width=4 and align="right".

The results are as you expect when width=3:

> A1b <- rollapply(A1a,4,mean, na.rm=TRUE, na.pad=FALSE, align="right")
> cbind(A1a,A1b)
   A1a A1b
1   NA  NA
2   NA  NA
3    1 1.0
4    2 1.5
5    3 2.0
6    4 3.0
7    5 4.0
8    6 5.0
9   NA 5.5
10  NA 6.0

HTH,
--
Joshua Ulrich  |  FOSS Trading: www.fosstrading.com


>
>> mean(c(1,NA, NA), na.rm=TRUE)
> [1] 1
>
>> A1a<-zoo(c(NA, NA, 1,2,3,4,5,6, NA, NA))
>> A1b<-rollapply(A1a,4,mean, na.rm=TRUE, na.pad=FALSE, align="right")
>> View(cbind(A1a,A1b))
>> cbind(A1a,A1b)
>   A1a A1b
> 1   NA  NA
> 2   NA  NA
> 3    1  NA
> 4    2 1.5
> 5    3 2.0
> 6    4 2.5
> 7    5 3.5
> 8    6 4.5
> 9   NA 5.0
> 10  NA 5.5
>
> -----
> Christian Langkamp
> christian.langkamp-at-gmxpro.de
>
> --
> View this message in context: http://r.789695.n4.nabble.com/Zoo-bug-tp2287282p3065458.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>