Running examples in ‘plink-Ex.R’ failed
The error most likely occurred in:

> base::assign(".ptime", proc.time(), pos = "CheckExEnv")
> ### Name: gpcm-methods
> ### Title: Generalized Partial Credit Model Response Probabilities
> ### Aliases: gpcm gpcm-methods gpcm,matrix,numeric-method
> ###   gpcm,data.frame,numeric-method gpcm,list,numeric-method
> ###   gpcm,irt.pars,ANY-method gpcm,sep.pars,ANY-method
> ### Keywords: methods distribution
> 
> ### ** Examples
> 
> ###### Unidimensional Examples ######
> ## Partial Credit Model
> ## Item parameters from Embretson & Reise (2000, p. 108) item 5
> b <- t(c(-2.519,-.063,.17,2.055))
> x <- gpcm(b,5)
> plot(x) 
> 
> ## Generalized Partial Credit Model
> ## Item parameters from Embretson & Reise (2000, p. 112) items 5-7
> a <- c(.683,1.073,.583)
> b <- matrix(c(-3.513,-.041,.182,NA,-.873,.358,-.226,
+   1.547,-4.493,-.004,NA,NA),3,4,byrow=TRUE)
> pars <- cbind(a,b) # Does not include a location parameter
> rownames(pars) <- paste("Item",5:7,sep="") 
> colnames(pars) <- c("a",paste("b",1:4,sep=""))
> cat <- c(4,5,3)
> x <- gpcm(pars,cat,seq(-3,3,.05))
> plot(x)
> 
> ## Item parameters from Muraki (1996, p. 154)
> a <- c(1,.5)
> b <- matrix(c(.25,-1.75,1.75,.75,-1.25,1.25),2,3,byrow=TRUE)
> pars <- cbind(a,b) # Include a location parameter
> rownames(pars) <- paste("Item",1:2,sep="")
> colnames(pars) <- c("a","b",paste("d",1:2,sep=""))
> cat <- c(3,3)
> x <- gpcm(pars,cat,location=TRUE,print.mod=TRUE, D=1.7)
Generalized Partial Credit Model 
> # Plot category curves for two items
> matplot(x@prob$theta,x@prob[,2:4],xlab="Theta",ylab="Probability",
+   ylim=c(0,1),lty=1,type="l",col="black") 
> par(new=TRUE)
> matplot(x@prob$theta,x@prob[,5:7],xlab="Theta",ylab="Probability",
+   ylim=c(0,1),lty=3,type="l",col="black") 
> 
> 
> ###### Multidimensional Examples ######
> ## Multidimensional Partial Credit Model
> pars <- matrix(c(2.4207,0.245,-1.1041,NA,
+ 2.173,-0.4576,NA,NA,
+ 2.1103,-0.8227,.4504,NA,
+ 3.2023,1.0251,-.7837,-1.3062),4,4,byrow=TRUE)
> cat <- c(4,3,4,5)
> x <- gpcm(pars,cat,dimensions=2,print.mod=TRUE)
Multidimensional Partial Credit Model 
> # plot combined item category surfaces
> # The screen argument adjusts the orientation of the axes
> plot(x,screen=list(z=-60,x=-70))
> 
> ## Multidimensional Generalized Partial Credit Model
> a <- matrix(c(.873, .226, .516, .380, .613, .286 ),3,2,byrow=TRUE)
> b <- matrix(c(2.255, 1.334, -.503, -2.051, -3.082,
+ 1.917, 1.074, -.497, -1.521, -2.589,
+ 1.624, .994, -.656, -1.978, NA),3,5,byrow=TRUE)
> pars <- cbind(a,b)
> cat <- c(6,6,5)
> x <- gpcm(pars,cat,dimensions=2,print.mod=TRUE)
Multidimensional Generalized Partial Credit Model 
> 
> # plot combined item category surfaces
> plot(x,screen=list(z=-40,x=-60), auto.key=list(space="right"))
> 
> # plot separated item category surfaces for item two
> plot(x,items=2,separate=TRUE,drape=TRUE,panels=1)
> 
> # Compute response probabilities for a single three-category item with
> # three dimensions. Plot the response surfaces for the first two 
> # dimensions conditional on each theta value on the third dimension
> pars <- matrix(c(1.1999,0.5997,0.8087,2.1730,-1.4576),1,5)
> x <- gpcm(pars,3,dimensions=3,theta=-4:4)
> plot(x, screen=list(z=-30,x=-60))
Error in unit(0.5 * showr, "strwidth", list(right)) : 
  no string supplied for 'strwidth/height' unit
Calls: plot ... printFunction -> strip -> strip.default -> paste.and.draw -> unit
Execution halted