Error(s) in re-building vignettes:
--- re-building ‘sf1.Rmd’ using rmarkdown
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.
--- finished re-building ‘sf1.Rmd’

--- re-building ‘sf2.Rmd’ using rmarkdown
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.
--- finished re-building ‘sf2.Rmd’

--- re-building ‘sf3.Rmd’ using rmarkdown
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.
--- finished re-building ‘sf3.Rmd’

--- re-building ‘sf4.Rmd’ using rmarkdown
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.
--- finished re-building ‘sf4.Rmd’

--- re-building ‘sf5.Rmd’ using rmarkdown
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.
Quitting from lines 211-213 (sf5.Rmd) 
Error: processing vignette 'sf5.Rmd' failed with diagnostics:
cannot open the connection
--- failed re-building ‘sf5.Rmd’

--- re-building ‘sf6.Rmd’ using rmarkdown
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.
--- finished re-building ‘sf6.Rmd’

--- re-building ‘sf7.Rmd’ using rmarkdown
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.
Quitting from lines 163-164 (sf7.Rmd) 
Error: processing vignette 'sf7.Rmd' failed with diagnostics:
object 'oc' not found
--- failed re-building ‘sf7.Rmd’

SUMMARY: processing the following files failed:
  ‘sf5.Rmd’ ‘sf7.Rmd’

Error: Vignette re-building failed.
Execution halted