Error in re-building vignettes:
  ...
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
trying URL 'http://cran.rstudio.com/src/contrib/colorspace_1.3-2.tar.gz'
Content type 'application/x-gzip' length 293433 bytes (286 KB)
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downloaded 286 KB

trying URL 'http://cran.rstudio.com/src/contrib/labeling_0.3.tar.gz'
Content type 'application/x-gzip' length 10722 bytes (10 KB)
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downloaded 10 KB

trying URL 'http://cran.rstudio.com/src/contrib/munsell_0.5.0.tar.gz'
Content type 'application/x-gzip' length 182653 bytes (178 KB)
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downloaded 178 KB

trying URL 'http://cran.rstudio.com/src/contrib/RColorBrewer_1.1-2.tar.gz'
Content type 'application/x-gzip' length 11532 bytes (11 KB)
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downloaded 11 KB

trying URL 'http://cran.rstudio.com/src/contrib/reshape2_1.4.3.tar.gz'
Content type 'application/x-gzip' length 36405 bytes (35 KB)
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downloaded 35 KB

trying URL 'http://cran.rstudio.com/src/contrib/scales_1.0.0.tar.gz'
Content type 'application/x-gzip' length 299262 bytes (292 KB)
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downloaded 292 KB

trying URL 'http://cran.rstudio.com/src/contrib/viridisLite_0.3.0.tar.gz'
Content type 'application/x-gzip' length 44019 bytes (42 KB)
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downloaded 42 KB

trying URL 'http://cran.rstudio.com/src/contrib/ggplot2_3.1.0.tar.gz'
Content type 'application/x-gzip' length 2863109 bytes (2.7 MB)
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downloaded 2.7 MB

* installing *source* package ‘colorspace’ ...
** package ‘colorspace’ successfully unpacked and MD5 sums checked
** libs
/opt/csw//bin/gcc -I"/home/ripley/R/gcc/include" -DNDEBUG   -I/opt/csw/include -I/usr/local/include   -fPIC  -O2  -c colorspace.c -o colorspace.o
/opt/csw//bin/gcc -shared -L/usr/local/lib -L/opt/csw/lib -L/opt/developerstudio12.5/lib -o colorspace.so colorspace.o
installing to /tmp/RtmpIaayIK/RLIBS_4913447f26de/colorspace/libs
** R
** data
*** moving datasets to lazyload DB
** inst
** byte-compile and prepare package for lazy loading
** help
*** installing help indices
** building package indices
** installing vignettes
** testing if installed package can be loaded
* DONE (colorspace)
* installing *source* package ‘labeling’ ...
** package ‘labeling’ successfully unpacked and MD5 sums checked
** R
** byte-compile and prepare package for lazy loading
** help
*** installing help indices
** building package indices
** testing if installed package can be loaded
* DONE (labeling)
* installing *source* package ‘RColorBrewer’ ...
** package ‘RColorBrewer’ successfully unpacked and MD5 sums checked
** R
** inst
** byte-compile and prepare package for lazy loading
** help
*** installing help indices
** building package indices
** testing if installed package can be loaded
* DONE (RColorBrewer)
* installing *source* package ‘reshape2’ ...
** package ‘reshape2’ successfully unpacked and MD5 sums checked
** libs
/opt/csw//bin/g++ -I"/home/ripley/R/gcc/include" -DNDEBUG  -I"/tmp/RtmpIaayIK/RLIBS_4913447f26de/Rcpp/include" -I/opt/csw/include -I/usr/local/include   -fPIC  -O2  -c RcppExports.cpp -o RcppExports.o
/opt/csw//bin/g++ -I"/home/ripley/R/gcc/include" -DNDEBUG  -I"/tmp/RtmpIaayIK/RLIBS_4913447f26de/Rcpp/include" -I/opt/csw/include -I/usr/local/include   -fPIC  -O2  -c melt.cpp -o melt.o
/opt/csw//bin/g++ -shared -L/usr/local/lib -L/opt/csw/lib -L/opt/developerstudio12.5/lib -o reshape2.so RcppExports.o melt.o
installing to /tmp/RtmpIaayIK/RLIBS_4913447f26de/reshape2/libs
** R
** data
*** moving datasets to lazyload DB
** inst
** byte-compile and prepare package for lazy loading
** help
*** installing help indices
** building package indices
** testing if installed package can be loaded
* DONE (reshape2)
* installing *source* package ‘viridisLite’ ...
** package ‘viridisLite’ successfully unpacked and MD5 sums checked
** R
** data
*** moving datasets to lazyload DB
** byte-compile and prepare package for lazy loading
** help
*** installing help indices
*** copying figures
** building package indices
** testing if installed package can be loaded
* DONE (viridisLite)
* installing *source* package ‘munsell’ ...
** package ‘munsell’ successfully unpacked and MD5 sums checked
** R
** inst
** byte-compile and prepare package for lazy loading
** help
*** installing help indices
*** copying figures
** building package indices
** testing if installed package can be loaded
* DONE (munsell)
* installing *source* package ‘scales’ ...
** package ‘scales’ successfully unpacked and MD5 sums checked
** libs
/opt/csw//bin/g++ -I"/home/ripley/R/gcc/include" -DNDEBUG  -I"/tmp/RtmpIaayIK/RLIBS_4913447f26de/Rcpp/include" -I/opt/csw/include -I/usr/local/include   -fPIC  -O2  -c RcppExports.cpp -o RcppExports.o
/opt/csw//bin/g++ -I"/home/ripley/R/gcc/include" -DNDEBUG  -I"/tmp/RtmpIaayIK/RLIBS_4913447f26de/Rcpp/include" -I/opt/csw/include -I/usr/local/include   -fPIC  -O2  -c colors.cpp -o colors.o
/opt/csw//bin/g++ -shared -L/usr/local/lib -L/opt/csw/lib -L/opt/developerstudio12.5/lib -o scales.so RcppExports.o colors.o
installing to /tmp/RtmpIaayIK/RLIBS_4913447f26de/scales/libs
** R
** byte-compile and prepare package for lazy loading
** help
*** installing help indices
*** copying figures
** building package indices
** testing if installed package can be loaded
* DONE (scales)
* installing *source* package ‘ggplot2’ ...
** package ‘ggplot2’ successfully unpacked and MD5 sums checked
** R
** data
*** moving datasets to lazyload DB
** inst
** byte-compile and prepare package for lazy loading
** help
*** installing help indices
*** copying figures
** building package indices
** installing vignettes
** testing if installed package can be loaded
* DONE (ggplot2)

The downloaded source packages are in
	'/tmp/RtmpSFaOXL/downloaded_packages'
Quitting from lines 34-37 (single-images.Rmd) 
Error: processing vignette 'single-images.Rmd' failed with diagnostics:
STRING_ELT() can only be applied to a 'character vector', not a 'symbol'
Execution halted