Render and Preview snippets of TeX in R Viewer — tex

input TeX script into the function and it renders a pdf and converts it an image which is sent to Viewer.

tex_preview(
  obj,
  tex_lines = NULL,
  stem = "tex_temp",
  overwrite = TRUE,
  keep_pdf = FALSE,
  tex_message = FALSE,
  fileDir = tex_opts$get("fileDir"),
  margin = tex_opts$get("margin"),
  imgFormat = tex_opts$get("imgFormat"),
  returnType = tex_opts$get("returnType"),
  resizebox = tex_opts$get("resizebox"),
  usrPackages = tex_opts$get("usrPackages"),
  engine = tex_opts$get("engine"),
  cleanup = tex_opts$get("cleanup"),
  density = tex_opts$get("density"),
  svg_max = tex_opts$get("svg_max"),
  print.xtable.opts = tex_opts$get("print.xtable.opts"),
  opts.html = tex_opts$get("opts.html"),
  markers = interactive(),
  ...
)

Arguments

obj: object to convert to TeX script
tex_lines: vector of character, in case of special needs, instead of asking texPreview to build up, you may choose to pass in the contents of the complete LaTeX file directly. It should be a vector of character with each element as a line of raw TeX code.
stem: character, name to use in output files, Default: "tex_temp"
overwrite: logical, controls if overwriting of output stem* files given their existences, Default: TRUE
keep_pdf: logical, controls if the rendered pdf file should be kept or deleted, Default: FALSE
tex_message: logical, controls if latex executing messages are displayed in console. Default: FALSE
fileDir: character, output destination. If NULL a temp.dir() will be used and no output will be saved, Default: tex_opts$get('fileDir')
margin: table margin for pdflatex call, Default: tex_opts$get('margin')
imgFormat: character, defines the type of image the PDF is converted to Default: tex_opts$get('imgFormat')
returnType: character, one of "viewer", "html", or "tex" determining appropriate return type for the rendering process, Default: tex_opts$get('returnType')
resizebox: logical, forces a tabular tex object to be constrained on the margins of the document, Default: tex_opts$get('resizebox')
usrPackages: character, vector of usepackage commands, see details for string format
engine: character, specifies which latex to pdf engine to use ('pdflatex','xelatex','lualatex'), Default: tex_opts$get('engine')
cleanup: character, vector of file extensions to clean up after building pdf, Default: tex_opts$get('cleanup')
density: numeric, controls the density of the image. Default is 150: tex_opts$get('density)
svg_max: numeric, maximum svg file size allowable to preview, Default: tex_opts$get('svg_max')
print.xtable.opts: list, contains arguments to pass to print.table, relevant only if xtable is used as the input, Default: tex_opts$get('print.xtable.opts')
opts.html: list, html options, Default: tex_opts$get('opts.html')
markers: logical, if TRUE then RStudio markers will be invoked to create links for the log file on rendering errors, Default: interactive()
...: passed to system2

Value

The output of the function is dependent on the value of returnType:

viewer: NULL
- magick image is printed in the internal viewer
tex:
- character, TeX lines
- printed 'asis' in RMarkdown
input: character
- path to the file containing the tex wrapped in an input call
- printed 'asis' in RMarkdown
html: magick image
- Printed as an HTML document in the internal viewer
- Printed as an image in RMarkdown

Details

tex_preview is an S3 method that can be used to preview TeX output from different object classes.

Built-in support includes:

character (tex lines)
knitr_kable (kable/kableExtra)
xtable
texreg
equatiomatic

System Requirements

The function assumes the system has pdflatex installed and it is defined in the PATH.

TeX Packages

To add packages to the tex file on render there are two options

Use build_usepackage and use the input argument usrPackages.
Append to the input object \\usepackage{...} calls, they will be parsed and added the to rendering.

Images

An image file of the name stem with the extension specified in imgFormat.
The default extension is png.

Side effects

The function writes two files to disk in the fileDir
- Image file
- TeX script
The rendering files are removed up from the fileDir. This can be controlled using the cleanup argument or tex_opts$get('cleanup')

Examples

data('iris')
if(interactive()){

# Raw TeX

tex <- '\\begin{tabular}{llr}
\\hline
\\multicolumn{2}{c}{Item} \\\\
\\cline{1-2}
Animal    & Description & Price (\\$) \\\\
\\hline
Gnat      & per gram    & 13.65      \\\\
& each        & 0.01       \\\\
Gnu       & stuffed     & 92.50      \\\\
Emu       & stuffed     & 33.33      \\\\
Armadillo & frozen      & 8.99       \\\\
\\hline
\\end{tabular}'

# knitr kable

 mtcars |>
   head() |>
   knitr::kable("latex") |>
   tex_preview()

# with svg output pan/zoom is enabled in the internal viewer

tex_preview(obj = tex,stem = 'eq',imgFormat = 'svg')

# use tex_lines parameter to pass full document

tikz_path <- system.file(
                  'examples/tikz/credit_rationing.tex',
                  package = 'texPreview'
                  )

tex_preview(tex_lines = readLines(tikz_path))

}