[R] Vector recycling and zoo

[Gabor Grothendieck]

When you combine zoo objects with arithmetic it merges them using all = FALSE:

> library(zoo)
> x <- data.frame(a=1:5*2, b=1:5*3)
> x <- zoo(x); x
   a  b
1  2  3
2  4  6
3  6  9
4  8 12
5 10 15
>
> # these two are the same
>
> x$a/x$a[1]
1
1
>
> m <- merge(x$a, x$a[1], all = FALSE)
> m
  x$a x$a[1]
1   2      2
> m[,1]/m[,2]
1
1





On Sun, May 16, 2010 at 3:00 AM, Sean Carmody <seancarmody at gmail.com> wrote:
> I am a bit confused about the different approaches taken to recycling in
> plain data frames and zoo objects. When carrying out simple arithmetic,
> dataframe seem to recycle single arguments, zoo objects do not. Here is an
> example
>
>> x <- data.frame(a=1:5*2, b=1:5*3)
>> x
>   a  b
> 1  2  3
> 2  4  6
> 3  6  9
> 4  8 12
> 5 10 15
>> x$a/x$a[1]
> [1] 1 2 3 4 5
>> x <- zoo(x)
>> x$a/x$a[1]
> 1
> 1
>>
>
> I feel understanding this difference would lead me to a greater
> understanding of the zoo module!
>
> Sean.
>
> --
> Sean Carmody
> Twitter: http://twitter.com/seancarmody
> Stable: http://mulestable.net/sean
>
> The Stubborn Mule
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