[R] Cleaning up workspace

[Prof J C Nash (U30A)]

In order to have a clean workspace at the start of each chapter of a 
book I'm "knit"ing I've written a little script as follows:

# chapclean.R
# This cleans up the R workspace
ilist<-c(".GlobalEnv", "package:stats", "package:graphics", 
"package:grDevices",
"package:utils", "package:datasets", "package:methods", "Autoloads",
"package:base")
print(ilist)
xlist<-search()[which(!(search() %in% ilist))]
print(xlist)
for (ff in xlist){
    cat("Detach ",ff," which is pos ",as.integer(which(ff == 
search())),"\n")
    detach(pos=as.integer(which(ff == search())), unload=TRUE) # ?? do 
we need unload
}
rm(list=ls())


This appears to "work" fine in my system -- session info is below, but I 
get 30 warnings of the type

30: In FUN(X[[2L]], ...) :
   Created a package name, ‘2013-10-16 10:56:47’, when none found

Does anyone have ideas why the warnings are being generated?  I'd like 
to avoid suppressing them. Here's the session info.

R version 3.0.1 (2013-05-16)
Platform: x86_64-pc-linux-gnu (64-bit)

locale:
  [1] LC_CTYPE=en_CA.UTF-8       LC_NUMERIC=C
  [3] LC_TIME=en_CA.UTF-8        LC_COLLATE=en_CA.UTF-8
  [5] LC_MONETARY=en_CA.UTF-8    LC_MESSAGES=en_CA.UTF-8
  [7] LC_PAPER=C                 LC_NAME=C
  [9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_CA.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

loaded via a namespace (and not attached):
[1] tools_3.0.1
 >

John Nash