Hi
On 20/11/2010 2:10 p.m., Bryan Hanson wrote:
Oh Knowledgeable Ones:
I'm working on a project using grid graphics (for the first time). A toy
example is given below, run it simply with>foobar() I am wondering why the
pink dot and concentric circles are not centered on the 3-color axis system.
Further, I feel like the concentric circles don't have the intended radius -
if my math is right, the outmost circle should touch the ends of the colored
axes. My sense is that this has something to do with my mis-handling of the
viewports, but I can't quite see it. Any hints much appreciated!
It's your use of units. Both the points (by default) and the circles
(explicitly) are using "native" coordinates and the scales on the
viewport are both -5 to 5, so (0.5, 0.5) on those scales is slightly
off-centre. (0, 0) on those scales would be in the centre, as you have
specified for the segment start points.
Paul
Bryan
*************
Bryan Hanson
Professor of Chemistry& Biochemistry
DePauw University, Greencastle IN USA
foobar<- function() {
# a couple of convenience functions before we begin:
p2cX<- function(r, theta) x<- r*cos(theta*2*pi/360)
p2cY<- function(r, theta) y<- r*sin(theta*2*pi/360)
vp<- viewport(x = 0.5, y = 0.5, width = 0.8, height = 0.8,
xscale = c(-5, 5), yscale = c(-5, 5))
grid.newpage()
pushViewport(vp)
grid.rect(gp = gpar(lty = "dashed", col = "gray")) # reference/guide
grid.points(x = 0.5, y = 0.5, pch = 20, gp = gpar(col = "pink"), vp =
vp)
x0<- c(0,0,0)
y0<- c(0,0,0)
x1<- p2cX(c(4, 4, 4), c(0, 120, 240))
y1<- p2cY(c(4, 4, 4), c(0, 120, 240))
grid.segments(x0 = x0, y0 = y0, x1 = x1, y1 = y1,
gp = gpar(col = c("green", "blue", "red"), lwd = 2),
default.units = "native")
grid.circle(x = 0.5, y = 0.5, r = 1:4,
gp = gpar(col = "grey"), default.units = "native", vp = vp)
}
sessionInfo()
R version 2.12.0 (2010-10-15)
Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)
locale:
[1] en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8
attached base packages:
[1] splines datasets tools grid grDevices graphics utils
stats
[9] methods base
other attached packages:
[1] Hmisc_3.8-3 survival_2.35-8 gridExtra_0.7 GGally_0.2.2
[5] xtable_1.5-6 mvbutils_2.5.1 ggplot2_0.8.8 proto_0.3-8
[9] reshape_0.8.3 ChemoSpec_1.46 seriation_1.0-2
colorspace_1.0-1
[13] TSP_1.0-1 R.utils_1.5.3 R.oo_1.7.4
R.methodsS3_1.2.1
[17] rgl_0.92.794 lattice_0.19-13 mvoutlier_1.4 plyr_1.2.1
[21] RColorBrewer_1.0-2 chemometrics_1.0 som_0.3-5
robustbase_0.5-0-1
[25] rpart_3.1-46 pls_2.1-0 pcaPP_1.8-3 mvtnorm_0.9-92
[29] nnet_7.3-1 mclust_3.4.6 MASS_7.3-8 lars_0.9-7
[33] gclus_1.3 cluster_1.13.1 e1071_1.5-24 class_7.3-2
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--
Dr Paul Murrell
Department of Statistics
The University of Auckland
Private Bag 92019
Auckland
New Zealand
64 9 3737599 x85392
p...@stat.auckland.ac.nz
http://www.stat.auckland.ac.nz/~paul/
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
