Error(s) in re-building vignettes:
  ...
--- re-building ‘axis_position.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  The vignette engine knitr::rmarkdown is not available, because the rmarkdown package is not installed. Please install it.
Loading required package: cowplot
Loading required package: ggplot2

Attaching package: 'cowplot'

The following object is masked from 'package:ggplot2':

    ggsave

Loading required package: grid
--- finished re-building ‘axis_position.Rmd’

--- re-building ‘introduction.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  The vignette engine knitr::rmarkdown is not available, because the rmarkdown package is not installed. Please install it.
Loading required package: cowplot

Attaching package: 'cowplot'

The following object is masked from 'package:ggplot2':

    ggsave

Loading required package: viridisLite
--- finished re-building ‘introduction.Rmd’

--- re-building ‘plot_annotations.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  The vignette engine knitr::rmarkdown is not available, because the rmarkdown package is not installed. Please install it.
Loading required package: ggplot2

Attaching package: 'cowplot'

The following object is masked from 'package:ggplot2':

    ggsave

Warning in cor.test.default(mtcars$mpg, mtcars$disp, method = "sp") :
  Cannot compute exact p-value with ties
Quitting from lines 26-31 (plot_annotations.Rmd) 
Error: processing vignette 'plot_annotations.Rmd' failed with diagnostics:
object 'p1' not found
--- failed re-building ‘plot_annotations.Rmd’

--- re-building ‘plot_grid.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  The vignette engine knitr::rmarkdown is not available, because the rmarkdown package is not installed. Please install it.
Loading required package: cowplot
Loading required package: ggplot2

Attaching package: 'cowplot'

The following object is masked from 'package:ggplot2':

    ggsave

--- finished re-building ‘plot_grid.Rmd’

--- re-building ‘shared_legends.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  The vignette engine knitr::rmarkdown is not available, because the rmarkdown package is not installed. Please install it.
Loading required package: ggplot2

Attaching package: 'cowplot'

The following object is masked from 'package:ggplot2':

    ggsave

--- finished re-building ‘shared_legends.Rmd’

SUMMARY: processing the following file failed:
  ‘plot_annotations.Rmd’

Error: Vignette re-building failed
Execution halted