# [R] how to draw manifold?

Sun Nov 21 21:42:44 CET 2010

```Hi,

I'm joining in with a question -- is it possible to vary the color of
the lines along z? The 'colors' argument doesn't seem to allow a
vector in this situation.

Thanks,

baptiste

On 21 November 2010 21:02, Carl Witthoft <carl at witthoft.com> wrote:
> Thanks, Dennis.   Here's an enhanced version:
>
>  z <- seq(-10, 10, 0.1)
>  zm<-cbind(z,z,z,z,z,z,z,z,z,z)
>
> ym<-matrix(nr=201,nc=10)
> for (i in seq(1,201)) {
>        for (j in seq(1,10)) ym[i,j]<-j/10*sin(zm[i,1])}
>
> xm<-matrix(nr=201,nc=10)
> for (i in seq(1,201)) {
>        for (j in seq(1,10)) xm[i,j]<-j/10*cos(zm[i,1])}
>
>
> scatterplot3d(as.vector(t(xm)), as.vector(t(ym)), as.vector(t(zm)), main =
> 'Helix', pch = ".",type='l')
>
>
> From there I can draw a few helical lines by modifying your original code
> (for different radii), and end up with a pretty decent "mesh surface."
>
> Carl
>
>
> On 11/20/10 12:03 PM, Dennis Murphy wrote:
>>
>> Hi:
>>
>> Here's an example stolen out of the scatterplot3d package vignette (p. 9):
>>
>> library(scatterplot3d)
>> z<- seq(-10, 10, 0.01)
>> x<- cos(z)
>> y<- sin(z)
>> scatterplot3d(x, y, z, highlight.3d = TRUE, col.axis = 'blue',
>>               col.grid = 'lightblue', main = 'Helix', pch = 20)
>>
>> HTH,
>> Dennis
>>
>> On Sat, Nov 20, 2010 at 8:29 AM, Carl Witthoft<carl at witthoft.com>  wrote:
>>
>>> Hi,
>>> I need some help either in how to configure variables for wireframe(), or
>>> some suggestions as to other graphics commands to use for plotting a 2-D
>>> manifold in 3-D space.
>>>
>>> Here is an example I tried (in the hopes that it would plot a helical
>>> line)
>>> :
>>>
>>> xsp<-matrix(c(cos(seq(0,80)/5)),9,9)
>>> ysp<-matrix(c(sin(seq(0,80)/5)),9,9)
>>> zsp<-matrix(c((seq(0,80)/20)),9,9)
>>> wireframe(zsp~xsp*ysp)
>>>
>>> The resulting plot looks vaguely like a helix, but not right.  And if I
>>> change my variables' dimensions to c(3,27) it looks "better," but if the
>>> dims are c(1,81), nothing gets plotted.
>>>
>>> So: is there a way to control which points are connected by lines in
>>> wireframe()?  Or is there a more appropriate way to provide a plotting
>>> program with sets of coordinates in 3-space?
>>>
>>> My primary goal is to be able to plot surfaces, not just a line as in my
>>> sample code.  For example, I might expand the data above to represent
>>> points
>>> on a 'ribbon' helix.
>>>
>>> Thanks for yr. help -- feel free to point me to help files for existing
>>> packages or plotting routines.
>>>
>>> Carl
>>>
>>> ______________________________________________
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>>>
>>
>
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