When we are talking about table generators in R, knitr::kable wins lots of flavor by its ultimate simplicity. Unlike those powerful table rendering engines such as xtable, 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() (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.

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.

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.packages("kableExtra")

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

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"))
  

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

• 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.
• If you are using the CRAN version, when you run rmarkdown from console using RScript, you need to include library(methods) at the begining due to a rvest issue. By default, library(methods) is loaded in R GUI and RStudio. I eliminated the step requires rvest in current github version since it doesn't provide a very useful feature. See this SO post for details. Thanks twitter user @Gimperion for reporting.

• 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
• Find a way to let align table caption.