Running examples in 'genoPlotR-Ex.R' failed
The error most likely occurred in:

> ### Name: annotation
> ### Title: Annotation class and class functions
> ### Aliases: annotation as.annotation is.annotation
> ### Keywords: data
> 
> ### ** Examples
> 
> ## loading data
> data(three_genes)
> 
> ## Calculating middle positions
> mid_pos <- middle(dna_segs[[1]])
> 
> # Create first annotation
> annot1 <- annotation(x1=mid_pos, text=dna_segs[[1]]$name)
> plot_gene_map(dna_segs=dna_segs, comparisons=comparisons, annotations=annot1)
> 
> ## Exploring options
> annot2 <- annotation(x1=c(mid_pos[1], dna_segs[[1]]$end[2]),
+                      x2=c(NA, dna_segs[[1]]$end[3]),
+                      text=c(dna_segs[[1]]$name[1], "region1"),
+                      rot=c(30, 0), col=c("grey", "black"))
> plot_gene_map(dna_segs=dna_segs, comparisons=comparisons,
+               annotations=annot2, annotation_height=1.3)
> 
> ## Annotations on all the segments
> annots <- lapply(dna_segs, function(x){
+   mid <- middle(x)
+   annot <- annotation(x1=mid, text=x$name, rot=30)
+ })
> plot_gene_map(dna_segs=dna_segs, comparisons=comparisons,
+               annotations=annots, annotation_height=1.8, annotation_cex=1)
> 
> ##
> ## Using a bigger dataset from a 4-genome comparison
> ##
> data(barto)
> ## Adding a tree
> tree <- newick2phylog("(BB:2.5,(BG:1.8,(BH:1,BQ:0.8):1.9):3);")
> ## Showing several subsegments
> xlims2 <- list(c(1445000, 1415000, 1380000, 1412000),
+                c(  10000,   45000,   50000,   83000, 90000, 120000),
+                c(  15000,   36000,   90000,  120000, 74000,  98000),
+                c(   5000,    82000))
> ## Adding annotations for all genomes, allow segments to be placed out
> ## of the longest segment
> annots <- lapply(barto$dna_segs, function(x){
+   mid <- middle(x)
+   annot <- annotation(x1=mid, text=x$name, rot=30)
+   # removing gene names starting with "B" and keeping 1 in 4
+   idx <- grep("^[^B]", annot$text, perl=TRUE)
+   annot[idx[idx %% 4 == 0],] 
+ })
> plot_gene_map(barto$dna_segs, barto$comparisons, tree=tree,
+               annotations=annots,
+               xlims=xlims2,
+               limit_to_longest_dna_seg=FALSE,
+               dna_seg_scale=TRUE)
Error in valid.viewport(x, y, width, height, just, gp, clip, mask, xscale,  : 
  invalid 'xscale' in viewport
Calls: plot_gene_map -> pushViewport -> viewport -> valid.viewport
Execution halted