# Response surface plot

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## Response surface plot

 Dear List,    I am trying to plot a similar graph to attached from minitab manual in R.    I have a response Y and three components which systematically vary in their    proportions. I have found in R methods/packages to plot ternary plots (eg.    plotrix) but nothing which can extend it to response surface in 3-D.    Any help appreciated,    Tim Carnus ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code. reponse_surface.png (19K) Download Attachment
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## Re: Response surface plot

 On 5/12/2009 8:43 AM, Tim Carnus wrote: >    Dear List, >    I am trying to plot a similar graph to attached from minitab manual in R. >    I have a response Y and three components which systematically vary in their >    proportions. I have found in R methods/packages to plot ternary plots (eg. >    plotrix) but nothing which can extend it to response surface in 3-D. >    Any help appreciated, I'm not aware of anyone who has done this.  The way to do the surface in rgl would be to construct a mesh of triangles using tmesh3d, and set the color of each vertex as part of the material argument. It's a little tricky to get the colors right when they vary by vertex, but the code below gives an example. I would construct the mesh by starting with one triangle and calling subdivision3d, but you may want more control over them. For example: library(rgl) # First create a flat triangle and subdivide it triangle <- c(0,0,0,1, 1,0,0,1, 0.5, sqrt(3)/2, 0, 1) mesh <- tmesh3d( triangle, 1:3, homogeneous=TRUE) mesh <- subdivision3d(mesh, 4, deform=FALSE, normalize=TRUE) # Now get the x and y coordinates and compute the surface height x <- with(mesh, vb[1,]) y <- with(mesh, vb[2,]) z <- x^2 + y^2 mesh\$vb[3,] <- z # Now assign colors according to the height; remember that the # colors need to be in the order of mesh\$it, not vertex order. vcolors <- rainbow(100)[99*z+1] tricolors <- vcolors[mesh\$it] mesh\$material = list(color=tricolors) # Now draw the surface, and a rudimentary frame behind it. shade3d(mesh) triangles3d(matrix(triangle, byrow=TRUE, ncol=4), col="white") quads3d(matrix(c(1,0.5,0.5,1, 0,sqrt(3)/2, sqrt(3)/2,0, 0,0,1,1), ncol=3), col="white") bg3d("gray") Duncan Murdoch ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.