Problem with R source blocks

[tsd@tsdye.com (Thomas S. Dye)]

Aloha all,

Recently, some previously working R code (below) stopped working correctly.

It is not possible to produce a graphic without :session.  I get a red
message in the pdf file "arguments imply differing numbers of rows: 86,
79".

With :session, I first get one of two error messages in red in the pdf
file, either "Results must be all atomic, or all data frames" or
"subscript out of bounds".

With the "subscript out of bounds" error, if I run the source code block
again, I get the expected graphic.

With the "Results must be all atomic ..." message, if I re-run the
source code block several times, I see first an error "arguments imply
differing numbers of rows: 67, 60", then on the next run "arguments imply
differing numbers of rows: 86, 79" (like running outside a :session),
then the expected graphic.  Subsequent runs all produce the expected
graphic.

If I jump to the session, then print(g) works as expected, without any
error messages.

I haven't the faintest idea what might be happening, or how to debug.

#+begin_src emacs-lisp
(org-version)
#+end_src

#+results:
: 8.3beta

#+begin_src emacs-lisp
(emacs-version)
#+end_src

#+results:
: GNU Emacs 24.5.1 (x86_64-apple-darwin13.4.0, NS apple-appkit-1265.21)
:  of 2015-04-18 on tennine-slave.macports.org

All the best,
Tom

,-------------------------------------------------------------------------
| #+name: dated-interval-plot                                             
| #+header: :file ~/temp/test-plot.pdf                                    
| #+header: :var bcal = heiau-dates                                       
| #+header: :var base.font = 11                                           
| #+header: :var theme = "bw"                                             
| #+header: :var xlabel = "Years After Polynesian Discovery"              
| #+header: :var ylabel = "Probability"                                   
| #+header: :var rows=4                                                   
| #+header: :var cols=4                                                   
| #+header: :var xmin=0                                                   
| #+header: :var xmax=1000                                                
| #+header: :width 7 :height 5                                            
| #+header: :results graphics                                             
| #+BEGIN_SRC R :session                                                  
| library(ggplot2)                                                        
| library(ggthemes)                                                       
| bcal.df <- data.frame(cal=numeric(0),prob=numeric(0),label=character(0))
| for (i in seq(dim(bcal)[1]))                                            
| {                                                                       
|  t <- read.csv(file=bcal[i,1])                                          
|  names(t) <- c("cal","prob")                                            
|  t <- cbind(t,label=rep(bcal[i,2], dim(t)[1]))                          
|  bcal.df <- rbind(bcal.df,t)                                            
| }                                                                       
| switch(theme,                                                           
|     bw =, BW = theme_set(theme_bw(base_size=base.font)),                
|     grey =, gray = theme_set(theme_grey(base_size=base.font)),          
|     tufte = theme_set(theme_tufte(base_size=base.font)),                
|     calc = theme_set(theme_calc(base_size=base.font)),                  
|     econ =, economist = theme_set(theme_economist(base_size=base.font)),
|     excel = theme_set(theme_excel(base_size=base.font)),                
|     few = theme_set(theme_few(base_size=base.font)),                    
|     five = theme_set(theme_fivethirtyeight(base_size=base.font)),       
|     google =, gdocs = theme_set(theme_gdocs(base_size=base.font)),      
|     ## highchart =, hc = theme_set(theme_hc(base_size=base.font)),      
|     inverted = theme_set(theme_igray(base_size=base.font)),             
|     solarized = theme_set(theme_solarized(base_size=base.font)),        
|     solarized2 = theme_set(theme_solarized_2(base_size=base.font)),     
|     ## solid = theme_set(theme_solid(base_size=base.font)),             
|     stata = theme_set(theme_stata(base_size=base.font,scheme="s2mono")),
|     wsj = theme_set(theme_wsj(base_size=base.font)),                    
|     theme_set(theme_bw(base_size=base.font)))                           
| g <-  ggplot(bcal.df, aes(x=cal, y=prob))                               
| g <- g + geom_bar(stat='identity') + xlab(xlabel) + xlim(xmin,xmax)     
| g <- g + ylab(ylabel) + facet_wrap(~ label, nrow=rows, ncol=cols)       
| print(g)                                                                
| #+END_SRC                                                               
`-------------------------------------------------------------------------

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