kableExtra

When we are talking about table generators in R, knitr's kable() function wins lots of flavor by its ultimate simplicity. Unlike those powerful table rendering engines such as xtable, the philosophy behind knitr::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() (Or a good alternative for markdown tables is pander::pander()) 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

This package can load required LaTeX package automatically in vanilla rmarkdown. For customized rmarkdown templates, it is recommended to load related LaTeX packages manually.

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

install.packages("kableExtra")

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

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.

Limitations/Known bug

When you are using header-includes together with kableExtra, you cannot use inline R codes in header-includes. R code written in there won't be executed. It's a limitation of the current setup of rmarkdown.
In HTML, bootstrap_options in kable_styling assumes you to have bootstrap 3 style sheet loaded to have all features functioning.
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 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. You need to load required latex packages by yourself.