[R] map points from scatterplot3d onto 2d fitted plane
ligges at statistik.tu-dortmund.de
Sat Oct 25 21:32:45 CEST 2008
Jacqueline Hall wrote:
> Dear R helpers,
> I have a 3D scatter plot that I have generated from scatterplot3d (which
> looks great- thanks!) and I can see that the points in my graph fall in a
> Following the example 5 from 3D scatter plot (below) I have fitted a
> regression plane.
> Now what I would like to do is a rotation so that my new co-ordinate system
> is about the fitted plane (by finding the normal to the plane using
> crossprod?) and then map the data points onto this plane.
> I played with the function xyz.convert from s3d but i think this is mapping
> to the xy plane whereas i would like to map onto my fitted plane.
> Is there a package/function that can help me do this that I have missed? or
> does anyone have any suggestions / sample code to get me started in the
> right direction?
shows the package comes with a package vignette. Further on typing
shows the vignette which has been published (as a former more compact
Ligges, U. and Mächler, M. (2003). Scatterplot3d - an R Package for
Visualizing Multivariate Data. Journal of Statistical Software 8(11), 1-20.
See page 22 of the package vignette for an example that could be
rewritten for the trees data you used below as follows:
s3d <- scatterplot3d(trees, angle=55, scale.y=0.7, pch=16,
main="scatterplot3d - 5")
my.lm <- lm(Volume ~ Girth + Height, data = trees)
s3d$plane3d(my.lm, lty.box = "solid")
orig <- s3d$xyz.convert(trees)
plane <- s3d$xyz.convert(trees[,1], trees[,2], fitted(my.lm))
i.negpos <- 1 + (resid(my.lm) > 0)
segments(orig$x, orig$y, plane$x, plane$y,
col = c("blue", "red")[i.negpos], lty = (2:1)[i.negpos])
> Thanks very much for your help!
> ## example 5
> s3d <- scatterplot3d(trees, type="h", highlight.3d=TRUE,
> angle=55, scale.y=0.7, pch=16, main="scatterplot3d - 5")
> # Now adding a regression plane to the "scatterplot3d"
> my.lm <- lm(Volume ~ Girth + Height)
> s3d$plane3d(my.lm, lty.box = "solid")
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