[R] question on lag.zoo

[Gabor Grothendieck]

On Sun, Mar 2, 2008 at 9:28 AM, Gabor Grothendieck
<ggrothendieck at gmail.com> wrote:
> Its a FAQ.  x is of class "zoo" but z is of class "zooreg" so one is using

That should be lag.zooreg

> zoo.lag and the is using zooreg.lag.  See question #6 in the zoo FAQ:
>   vignette("zoo-faq")
> and also
>   ?lag.zoo
>
>
> On Sun, Mar 2, 2008 at 9:12 AM, Bo Zhou <bozhou1981 at hotmail.com> wrote:
> >
> > Hi Guys,
> >
> > I'm using zoo package now.  I found lag is not doing what I assumed.
> >
> > > x <- zoo(11:21)
> > > z <- zoo(1:10, yearqtr(seq(1959.25, 1961.5, by = 0.25)), frequency = 4)
> > > x
> >  1  2  3  4  5  6  7  8  9 10 11
> > 11 12 13 14 15 16 17 18 19 20 21
> > > lag(x)
> >  1  2  3  4  5  6  7  8  9 10
> > 12 13 14 15 16 17 18 19 20 21
> > > z
> > 1959 Q2 1959 Q3 1959 Q4 1960 Q1 1960 Q2 1960 Q3 1960 Q4 1961 Q1 1961 Q2 1961 Q3
> >      1       2       3       4       5       6       7       8       9      10
> > > lag(z)
> > 1959 Q1 1959 Q2 1959 Q3 1959 Q4 1960 Q1 1960 Q2 1960 Q3 1960 Q4 1961 Q1 1961 Q2
> >      1       2       3       4       5       6       7       8       9      10
> >
> >
> > Why z and lag (z) are of same length while lag(x) is shorter by one than x?
> >
> > I assume lag(z) would give me like this:
> > 1959 Q3 1959 Q4 1960 Q1 1960 Q2 1960 Q3 1960 Q4 1961 Q1 1961 Q2 1961 Q3
> >  2       3       4       5       6       7       8       9      10
> > ie preserve the relationship between timestamp and the value.
> >
> > Same things applies to lag(x) but I guess both make sense:
> >  1  2  3  4  5  6  7  8  9 10
> >
> > 12 13 14 15 16 17 18 19 20 21
> > or
> >  2  3  4  5  6  7  8  9 10 11
> >
> > 12 13 14 15 16 17 18 19 20 21
> >
> >
> > Any insight?
> >
> > Cheers,
> >
> > Bo
> >
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