This vignettes gives some detailled information regarding the Lua filter including in the rmarkdown package. To know more about Lua filter, you can jump directly to last section
Adding a pagebreak in document was always possible using custom output specific syntax in a rmarkdown file but one drawback was the compatibility with several output format.
Since rmarkdown >= 1.15 and with RStudio >= 1.2 (or with pandoc >= 2.0), it is possible to add a \newpage
or \pagebreak
command in a new line to include a pagebreak in any of these formats: pdf_document()
, html_document()
, word_document()
and odt_document()
.
# Header 1
Some text
\newpage
# Header 2 on a new page
Some other text
\pagebreak
# Header 3 on a third page
rmarkdown will convert those commands in the correct output format syntax using a Lua filter during pandoc conversion.
As the commands are the ones already used in latex syntax, this works as expected in a tex output document, and thus with pdf. Adding a pagebreak was already possible with rmarkdown when output is pdf_document()
or latex_document()
, without any restriction about the version of pandoc.
A \newpage
or \pagebreak
command in a rmarkdown document with output as HTML will be converted by default in this html code with inline style using CSS rule page-break-after
This will always insert a pagebreak after this div.
To get more flexibility, you can use a HTML class and some custom CSS instead of an inline style. You need to add a metadata field newpage_html_class
in your yaml header to set the class.
Then you can control the behavior using custom CSS as in this example
---
output:
html_document: default
newpage_html_class: page-break
---
```{css, echo = FALSE}
// display the pagebreak only when printing the html page
@media all {
.page-break { display: none; }
}
@media print {
.page-break { display: block; break-after: page; }
}
```
# Header 1
Some text
\newpage
# Header 2 on a new page
Some other text
\newpage
will be converted here to
and the style will be applied to this class from the CSS included in the chunk.
This customisation can also be achieved by setting the environnement variable PANDOC_NEWPAGE_HTML_CLASS
in the R session that will render the document (or in .Renviron
file for example)
Let’s note that in this example we use break-after
property instead of page-break-after
as it is recommended now to use the former which is the replacement. The latter is kept around for compatibility reason with browsers.
A \newpage
or \pagebreak
command in a rmarkdown document with output as Word document will be converted in a pagebreak for word document. Manually, this would mean adding this in your rmarkdown
For example, using the pagebreak feature, this will add the first header in the second page of the work document
To use the pagebreak feature with odt_document()
, you need to provide a reference document that includes a paragraph style with, by default, the name Pagebreak. This named paragraph style should have no extra space before or after and have a pagebreak after it. (see libre office documentation on how to create a style).
The name of the named paragrah style could be customized using newpage_odt_style
metadata in yaml header or PANDOC_NEWPAGE_ODT_STYLE
environment variable (as in html document).
As the previous one, this example will lead to a two pages document, with first header on the second page.
Numbering sections are supported by Pandoc for limited formats (e.g., html and pdf). The rmarkdown package adds number_sections.lua
to support this feature in other formats (e.g., docx, odt, and so on). Users do not have to know which formats use the Pandoc’s feature or the Lua filter.
---
title: My main title
output:
md_document:
number_sections: true # implemented by Lua filter
html_document
number_sections: true # implemented by Pandoc
---
# First Header
## A Header Belonging the First Header
# Second Header
In general, numbers and titles of sections are separated by a space. An exception is the word_document
function, which separates them by a tab in order to be consistent with Pandoc’s number sections for docx format in Pandoc >= 2.10.1. If one wants to have fine controls on the format of section numbers, prepare customized docx file and specify it to the reference_docx
argument of the word_document
function.
Since pandoc 2.0, it is possible to use Lua filters to add some extra functionality to pandoc document conversion. Adding a pagebreak command in markdown to be compatible with several output documents is one of them. You can find some more informations about Lua filters in pandoc’s documentation and also some examples in a collection of Lua filters for pandoc. These examples, and any other Lua filters, can be use in your Rmarkdown document directly by adding a pandoc argument in yaml header
You can also use a special helper using a !expr
syntax for yaml in your header
The package rmdfiltr provides a collection of Lua filters and helpers functions to use them.
Before pandoc 2.0, using filter with pandoc was already available through programs that modifies the AST. pandoc-citeproc
is an example used to deal with citations. The package pandocfilter is useful to create filters using R.
If you want to create a format that uses a special filter, you can add it as a pandoc option if the output format.
Either by modifying an existing format:
custom_format <- function(...) {
base_format <- rmarkdown::html_document(...)
# prepending a new Lua filter to html_document() ones
base_format$pandoc$lua_filters <- c(
rmarkdown::pandoc_path_arg("new.lua"),
base_format$pandoc$lua_filters)
base_format
}
basename(custom_format()$pandoc$lua_filters)
#> [1] "new.lua" "pagebreak.lua" "latex-div.lua"
Or by creating a new format :
custom_format <- function(toc = TRUE, ...) {
rmarkdown::output_format(
knitr = rmarkdown::knitr_options(),
# a new filter will be appended to base_format ones
pandoc = rmarkdown::pandoc_options(to = "html", lua_filters = "new.lua"),
base_format = rmarkdown::html_document(toc = toc, ...)
)
}
basename(custom_format()$pandoc$lua_filters)
#> [1] "pagebreak.lua" "latex-div.lua" "new.lua"
As this is an advanced feature, if you want to go further, we encourage you to look at the examples of formats in packages such as rmarkdown, bookdown or pagedown.