[R] Plotting the complex fft in 3D?

[Oliver Bandel]

Zitat von Duncan Murdoch <murdoch at stats.uwo.ca>:

> Oliver Bandel wrote:
> > Hello,
> >
> >
> > I'm new to R (using it since about two weeks),
> > but absolutely a fan of it from the beginning on. :-)
> >
> > Best tool for working with data I found. :-)
> >
> > I tried using the fft() and other funcitons for
> > analysing time series.
> >
> > What I would be glad to have, would be a
> > convenient way to display the complex result
> > of a fft in a way, that real and imaginary parts
> > each use an axis for themselves, and the index of the
> > resulting values use the third axe.
> >
> > When displaying this as a 3D->2D picture,
> > it also would be nice, to change the view,
> > like it can be done with persp().
> >
> > Is there already a package or script for preparing the data
> > of an fft to be displayed in this way?
>
> I don't find this very enlightening, but here you go:
>
> x <- rnorm(1000)
> f <- fft(x)
>
> library(rgl)
> plot3d(1:length(f), Re(f), Im(f))
[...]

Ok, this is a starting point. :-)

It would be enlightening, if you have a timeseries that is not
noise only, and if the plot would not use dots.
So, using a timeseries that is derived from some  data
could be very interesting. But rnorm creates noise only,
and not a deterministic signal. So the resulting fft values
look quite boring ;-)

Instead of dots, a line from the index-axis at Re=0, Im=0
to the value of the fft at that index should be drawn.

BTW: how to change the perspective? I did not found an
angle-parameter for the plot3d()-function.

Ciao,
   Oliver