kableExtra

When we are talking about table generators in R, knitr::kable wins the favor of a lot of people by its ultimate simplicity. Unlike those powerful table rendering engine such as xtable, tables or even gridExtra, the philosophy behind kable is to make it easy for programmers to use. Just as it claimed in its function description,

This is a very simple table generator. It is simple by design. It is not intended to replace any other R packages for making tables. - Yihui

However, the ultimate simplicity of kable() also brought troubles to some of us, especially for new R users, who may not have a lot of experience on generating tables in R. It is not rare to see people including experienced users asking questions like how to center/left-align a table on Stack Overflow. Also, for me personally, I found myself repeatedly parsing CSS into kable() for some very simple features like striped lines. For LaTeX, it's even worse since I'm almost Stack Overflow dependent for LaTeX... That's why this package kableExtra was created.

I hope with kableExtra, you can

• Use default base kable() for all simple tables
• Use kable() with kableExtra to generate 90 % of complex/advanced/self-customized/beautiful tables in either HTML or LaTeX
• Only have to mess with raw HTML/LaTeX in the last 10% cases where kableExtra cannot solve the problem

Features

Pipable syntax

kableExtra is NOT a table generating package. It is a package that can "add features" to a kable() output using a syntax that every useR loves - the pipes %>%. We see similar approaches to deal with plots in packages like ggvis and plotly. There is no reason why we cannot use it with tables.

Unified functions for both HTML and PDF

Most functionalities in kableExtra can work in both HTML and PDF. In fact, as long as you specifies format in kable() (which can be set globally through option knitr.table.format), functions in this package will pick the right way to manipulate the table be themselves. As a result, if users want to left align the table, kable(...) %>% kable_styling(position = "left") will work in both HTML and PDF.

Install

Some LaTeX features in kableExtra, such as striped line, requires rmarkdown 1.4.0+, which is not yet on CRAN. It is highly recommended to install the dev version of rmarkdown before you try this package. If you only use this package for HTML table, it doesn't matter what version of rmarkdown you are using.

# install.packages("devtools")
devtools::install_github("rstudio/rmarkdown")

# For dev version
devtools::install_github("haozhu233/kableExtra")

kableExtra will be submitted to CRAN soon.

Basic Usage

library(knitr)
library(kableExtra)
dt <- mtcars[1:5, 1:4]

# HTML table
kable(dt, format = "html", caption = "Demo Table") %>%
  kable_styling(bootstrap_options = "striped", 
                full_width = F) %>%
  add_header_above(c(" ", "Group 1" = 2, "Group 2[note]" = 2)) %>%
  add_footnote(c("table footnote"))

# LaTeX Table
kable(dt, format = "latex", booktabs = T, caption = "Demo Table") %>%
  kable_styling(latex_options = c("striped", "hold_position"), 
                full_width = F) %>%
  add_header_above(c(" ", "Group 1" = 2, "Group 2[note]" = 2)) %>%
  add_footnote(c("table footnote"))
  

Results

More Information

For more information, please check the package vignette.

• Create Awesome HTML Table with knitr::kable and kableExtra
• Create Awesome LaTeX Table with knitr::kable and kableExtra

Limitations

• add_header_above and add_footnote should be able to work in any conditions but if you are using kable_styling in customed templates it can get a little tricky.
• In HTML, kable_styling assumes you to have bootstrap 3 style sheet loaded to have all features functioning.
• In LaTeX, it is known that striped lines is not working with tufte handout since right now I cannot insert a latex package to its LaTeX header.

To-do

• A function to insert a gap row (or group title row in the middle of a table)
• A function to easily add title column indent
• Some ways to change text/background color of cells