[R] Error in calcCurveGrob(x, x$debug) : End points must not be identical

[Paul Murrell]

Hi

Bryan Hanson wrote:
> Hi All... I haven¹t found mention of this error anywhere.  I'm trying to
> draw spline curves using grid graphics.  Most of the time, I have no
> problems, but I have some data sets that give the error in the subject line.
> I'm not sure which end points are identical, but the end points passed to
> the function are definitely not identical.

I get ...

  which(tst$x.st == tst$x.end & tst$y.st == tst$y.end)
[1] 11 14

Also, the viewport you have set up will not show any of the curves 
because its "native" scale is 0 to 1.  The following at least makes the 
curves visible ...

grid.newpage()
vp <- viewport(width = 0.9, height = 0.9, x = 0.5, y = 0.5,
                xscale=c(-10, 10), yscale=c(-15, 15))
pushViewport(vp)
grid.rect(gp = gpar(lty = "dashed", col = "gray"))
grid.points(0.5, 0.5, pch = 20, gp = gpar(cex = 0.5))
subset <- -c(11, 14)
grid.curve(tst$x.st[subset], tst$y.st[subset],
            tst$x.end[subset], tst$y.end[subset],
            default.units = "native")

Paul

p.s.  Intrigued to know what sort of image you are producing, if you are 
able to share.

> 
> Any assistance appreciated!  Bryan
> 
> tst <-
> structure(list(x.st = c(-1, -2, -3, -1, -1.5, -3, -1.5, -1.5,
> -8, -1, -1.5, -1, -1.5, -2, -1.5, -2, -1, -1.5, -2), y.st =
> c(1.73205080756888,
> 3.46410161513776, 5.19615242270663, 1.73205080756888, 2.59807621135332,
> 5.19615242270663, 2.59807621135332, 2.59807621135332, 13.8564064605510,
> 1.73205080756888, 2.59807621135332, 1.73205080756888, 2.59807621135332,
> 3.46410161513776, 2.59807621135332, 3.46410161513776, 1.73205080756888,
> 2.59807621135332, 3.46410161513776), x.end = c(-6.5, -6.5, -6.5,
> -4, -4, -4, -1.5, -1, -1, -1.5, -1.5, -2, -2, -2, -3, -3, -8,
> -8, -8), y.end = c(-11.2583302491977, -11.2583302491977, -11.2583302491977,
> -6.92820323027551, -6.92820323027551, -6.92820323027551, -2.59807621135332,
> 1.73205080756888, 1.73205080756888, 2.59807621135332, 2.59807621135332,
> 3.46410161513776, 3.46410161513776, 3.46410161513776, 5.19615242270663,
> 5.19615242270663, 13.8564064605510, 13.8564064605510, 13.8564064605510
> ), grp = c(3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
> 3, 3), lwd = c(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 3, 1, 1, 1,
> 2, 5, 2)), .Names = c("x.st", "y.st", "x.end", "y.end", "grp",
> "lwd"), row.names = 34:52, class = "data.frame")
> 
> grid.newpage()
> vp <- viewport(width = 0.9, height = 0.9, x = 0.5, y = 0.5)
> pushViewport(vp)
> grid.rect(gp = gpar(lty = "dashed", col = "gray"))
> grid.points(0.5, 0.5, pch = 20, gp = gpar(cex = 0.5))
> grid.curve(tst$x.st, tst$y.st, tst$x.end, tst$y.end,
>     default.units = "native")
> 
> #######
>> 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] datasets  tools     grid      grDevices graphics  utils
> [7] stats     methods   base
> 
> other attached packages:
>  [1] gridExtra_0.7      GGally_0.2.2       xtable_1.5-6
>  [4] mvbutils_2.5.1     ggplot2_0.8.8      proto_0.3-8
>  [7] reshape_0.8.3      ChemoSpec_1.46     seriation_1.0-2
> [10] colorspace_1.0-1   TSP_1.0-1          R.utils_1.5.3
> [13] R.oo_1.7.4         R.methodsS3_1.2.1  rgl_0.92.794
> [16] lattice_0.19-13    mvoutlier_1.4      plyr_1.2.1
> [19] RColorBrewer_1.0-2 chemometrics_1.0   som_0.3-5
> [22] robustbase_0.5-0-1 rpart_3.1-46       pls_2.1-0
> [25] pcaPP_1.8-3        mvtnorm_0.9-92     nnet_7.3-1
> [28] mclust_3.4.6       MASS_7.3-8         lars_0.9-7
> [31] gclus_1.3          cluster_1.13.1     e1071_1.5-24
> [34] 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
paul at stat.auckland.ac.nz
http://www.stat.auckland.ac.nz/~paul/