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

[Bryan Hanson]

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.

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   
>