[R] adress the current index
Thomas Petzoldt
thpe at hhbio.wasser.tu-dresden.de
Tue May 25 17:25:37 CEST 2004
Mag. Ferri Leberl wrote:
> How can I adress the current index of a vector?
>
> I want to work with time series and therefore give the n-th element of a
> vector some value dependent on the value of the n-1th element.
Sorry, your question is not really clear, but possibly the following may
help:
1) If you have a vector x, you can create a shifted vector by removing
the first element, e.g.:
xnew <- x[-1] + somevalue # or apply a function f(x[-1])
2) The last element can be removed with:
xnew <- x[-length(x)]
3) ... and sometimes vector concatenation ?c or the ?ifelse function can
be useful in such circumstances.
Thomas P.
PS: there is more about such things in the docs.
More information about the R-help
mailing list