Normally that would be written like this using the coredata extraction function which extracts the data portion of a zoo object:
x$a / coredata( x$a[1] ) On Sun, May 16, 2010 at 7:32 PM, Sean Carmody <seancarm...@gmail.com> wrote: > Thanks David, > > You comment made me realise that whereas when x is a data frame, x$a is a > numeric vector, > when x is of class zoo, x$a is also of class zoo, so the following does what > I was expecting: > > x$a/as.numeric(x$a[1]) > > Sean. > > On Sun, May 16, 2010 at 9:25 PM, David Winsemius > <dwinsem...@comcast.net>wrote: > >> >> On May 16, 2010, at 2:00 AM, Sean Carmody 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! >>> >> >> I think you do have misunderstandings about the zoo package but I do not >> think it is in the area of vector recycling. Notice the effect of your >> application of the zoo function to x: >> >> > x$a >> >> 1 2 3 4 5 >> 2 4 6 8 10 >> > x$a[1] >> 1 >> 2 >> >> You have in effect transposed the elements in x and are now getting a two >> element column vector when requesting x$a[1]. The term vector recycling is >> applied to situations where short vectors are reused starting with their >> first elements until the necessary length is achieved. For instance if you >> request: >> >> > data.frame(x=1:2, y=letters[1:10]) >> x y >> 1 1 a >> 2 2 b >> 3 1 c >> 4 2 d >> 5 1 e >> 6 2 f >> 7 1 g >> 8 2 h >> 9 1 i >> 10 2 j >> >> Or plot(1:10, col=c("red","green")) >> >> >>> Sean. >>> >>> -- >>> Sean Carmody >>> >> >> >> > > > -- > Sean Carmody > Twitter: http://twitter.com/seancarmody > Stable: http://mulestable.net/sean > > The Stubborn Mule > Blog: http://www.stubbornmule.net > Forum: http://mulestable.net/ > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@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. > ______________________________________________ R-help@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.