knitr v1.17


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by Yihui Xie

A General-Purpose Package for Dynamic Report Generation in R

Provides a general-purpose tool for dynamic report generation in R using Literate Programming techniques.



Build Status Coverage Status Downloads from the RStudio CRAN mirror

The R package knitr is a general-purpose literate programming engine, with lightweight API's designed to give users full control of the output without heavy coding work. It combines many features into one package with slight tweaks motivated from my everyday use of Sweave. See the package homepage for details and examples. See FAQ's for a list of frequently asked questions (including where to ask questions).


You can install the stable version on CRAN:

install.packages('knitr', dependencies = TRUE)

You can also install the development version from XRAN, which provides daily build of knitr:

# update all existing packages first
update.packages(ask = FALSE, repos = '')
install.packages('knitr', repos = c('', ''))

Or use devtools to install the development version from Github:

devtools::install_github('yihui/knitr', build_vignettes = TRUE)


While Sweave and related add-on packages like cacheSweave and pgfSweave are fairly good engines for literate programming in R, but I often feel my hands are tied, for example:

  • I stared at the source code of Sweave and wished for hundreds of times that if only I could easily insert [width=.8\textwidth] between \includegraphics and {my-plot.pdf} (the official way in Sweave is \setkeys{Gin} but it is setting a global width, which is unrealistic since we often have to set widths individually; yes, you can use \setkeys{Gin} for many times, but why not just provide an option for each chunk?)
  • I wished for many times that if only I could use graphics devices other than PDF and postscript; now the dream has come true in the official R, but what I was hoping for was an option as simple as dev = 'png' or dev = 'CairoJPEG'
  • I wished multiple plots in a code chunk could be recorded instead of only the last one
  • I wished there was a way to round the numbers in \Sexpr{} other than writing expressions like \Sexpr{round(x, 3)} for each single \Sexpr{}
  • I wished I did not have to print() plots from ggplot2 and a simple qplot(x, y) would just give me a plot in Sweave
  • I wished users would never need instructions on Sweave.sty or run into troubles due to the fact that LaTeX cannot find Sweave.sty
  • I wished cacheSweave could print the results of a code chunk even if it was cached
  • I wished brew could support graphics
  • I wished R2HTML could support R code syntax highlighting
  • ...

The book Dynamic Documents with R and knitr

The package knitr was designed to give the user access to every part of the process of dealing with a literate programming document, so there is no need to hack at any core components if you want more freedom. I have gone through the source code of pgfSweave and cacheSweave for a couple of times, and I often feel uncomfortable with the large amount of code copied from official R, especially when R has a new version released (I will begin to worry if the add-on packages are still up-to-date with the official Sweave).



If options are not explicitly specified, knitr will try to guess reasonable default settings. A few manuals are available such as the main manual, and the graphics manual. For a more organized reference, see the knitr book.


This package is free and open source software, licensed under GPL.

Functions in knitr

Name Description
Sweave2knitr Convert Sweave to knitr documents
all_labels Get all chunk labels in a document
all_patterns All built-in patterns
asis_output Mark an R object with a special class
hook_pdfcrop Built-in chunk hooks to extend knitr
clean_cache Clean cache files that are probably no longer needed
combine_words Combine multiple words into a single string
current_input Query the current input filename
dep_auto Build automatic dependencies among chunks
dep_prev Make later chunks depend on previous chunks
include_graphics Embed external images in knitr documents
include_url Embed a URL as an HTML iframe or a screenshot in knitr documents
knit_engines Engines of other languages
knit_exit Exit knitting early
hook_movecode Some potentially useful document hooks
hook_plot_html Default plot hooks for different output formats
inline_expr Wrap code using the inline R expression syntax
kable Create tables in LaTeX, HTML, Markdown and reStructuredText
image_uri Encode an image file to a data URI
imgur_upload Upload an image to
knit2pandoc Convert various input files to various output files using knit() and Pandoc
knit2pdf Convert Rnw or Rrst files to PDF using knit() and texi2pdf() or rst2pdf()
knit_expand A simple macro preprocessor for templating purposes
knit_filter Spell check filter for source documents
opts_knit Options for the knitr package
knit_global The global environment in which code chunks are evaluated
knit_hooks Hooks for R code chunks, inline R code and output
knitr-package A general-purpose tool for dynamic report generation in R
load_cache Load the cache database of a code chunk
fig_path Path for figure files
hook_ffmpeg_html Hooks to create animations in HTML output
knit Knit a document
knit_print A custom printing function
knit_rd Knit package documentation
opts_chunk Default and current chunk options
opts_hooks Hooks for code chunk options
rand_seed An unevaluated expression to return .Random.seed if exists
extract_raw_output Mark character strings as raw output that should not be converted
vignette_engines Package vignette engines
wrap_rmd Wrap long lines in Rmd files
set_alias Set aliases for chunk options
set_header Set the header information
engine_output An output wrapper for language engine output
fig_chunk Obtain the figure filenames for a chunk
knit2wp Knit an R Markdown document and post it to WordPress
opts_template Template for creating reusable chunk options
pat_rnw Set regular expressions to read input documents
plot_crop Crop a plot (remove the edges) using PDFCrop or ImageMagick
set_parent Specify the parent document of child documents
spin Spin goat's hair into wool
knit_child Knit a child document
knit_meta Metadata about objects to be printed
knit_params Extract knit parameters from a document
knit2html Convert markdown to HTML using knit() and markdownToHTML()
knit_params_yaml Extract knit parameters from YAML text
knit_patterns Patterns to match and extract R code in a document
render_html Set output hooks for different output formats
pandoc A Pandoc wrapper to convert documents to other formats
rocco Knit R Markdown using the classic Docco style
rst2pdf A wrapper for rst2pdf
write_bib Generate BibTeX bibliography databases for R packages
knit_theme Syntax highlighting themes
knit_watch Watch an input file continuously and knit it when it is updated
read_chunk Read chunks from an external script
read_rforge Read source code from R-Forge
spin_child Spin a child R script
stitch Automatically create a report based on an R script and a template
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Vignettes of knitr

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Last month downloads


Type Package
Date 2017-08-09
License GPL
VignetteBuilder knitr
SystemRequirements Package vignettes based on R Markdown v2 or reStructuredText require Pandoc ( The function rst2pdf() require rst2pdf (
Collate 'block.R' 'cache.R' 'utils.R' 'citation.R' 'hooks-html.R' 'plot.R' 'defaults.R' 'concordance.R' 'engine.R' 'highlight.R' 'themes.R' 'header.R' 'hooks-asciidoc.R' 'hooks-chunk.R' 'hooks-extra.R' 'hooks-latex.R' 'hooks-md.R' 'hooks-rst.R' 'hooks-textile.R' 'hooks.R' 'output.R' 'package.R' 'pandoc.R' 'params.R' 'parser.R' 'pattern.R' 'rocco.R' 'spin.R' 'table.R' 'template.R' 'utils-base64.R' 'utils-conversion.R' 'utils-rd2html.R' 'utils-sweave.R' 'utils-upload.R' 'utils-vignettes.R' 'zzz.R'
RoxygenNote 6.0.1
NeedsCompilation no
Packaged 2017-08-09 06:32:13 UTC; yihui
Repository CRAN
Date/Publication 2017-08-10 04:27:37 UTC

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