R kableExtra latex: Add linebreaks to rotated header row - r

Question

I'm trying to produce table to a Latex-pdf document. I'm using kableExtra and knitr in R.
I have a table that has long column names. When I rotate the header row by 90 degrees linebreaks won't work. Does anyone have an idea how I could achieve both rotated row and linebreaks?
My example is the same as in Hao's Best Practice for newline in Latex table, but I added piped row_spec to the end of the code.
\documentclass[10pt,a4paper]{article}
\usepackage[table]{xcolor}
\begin{document}
\begin{table}
<<global_options, echo=FALSE>>=
library(kableExtra)
library("dplyr")
dt_lb <- data.frame(
Item = c("Hello\nWorld", "This\nis a cat"),
Value = c(10, 100)
)
dt_lb %>%
mutate_all(linebreak) %>%
kable("latex", booktabs = T, escape = F,
col.names = linebreak(c("Item\n(Name)", "Value\n(Number)"))) %>%
row_spec(0, angle = 90, align='l', monospace=T)
#
\end{table}
\end{document}
What I get is this, but the [l] tags hint that there's something else wrong with the tags as well:
On StackExchange TEX I found a question about rotation and linebreaks, this is what I'm trying achieve: https://tex.stackexchange.com/questions/14730/big-table-with-rotated-column-labels-using-booktabs

Answer 1

You could use tableHTML:
library(tableHTML)
Replace the new line character "\n" with the HTML tag <br>:
headers <- c("Item\n(Name)", "Value\n(Number)") %>%
stringr::str_replace_all(pattern = "\\n", replacement = "<br>")
Create a tableHTML object and rotate the headers using add_css_header():
dt_lb %>%
tableHTML(rownames = FALSE,
headers = headers,
escape = FALSE,
widths = c(100, 100),
theme = 'scientific') %>%
add_css_header(css = list(c('transform', 'height', 'text-align'),
c('rotate(-45deg)', '70px', 'center')),
headers = 1:2)
The result looks like this:
Note: you can add more css or default themes. Check out the vignettes for more details:
If you want to create a pdf document, you could use RMarkdown:
---
title: "tableHTML2pdf"
output: html_document
---
```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE)
```
\
```{r}
library(tableHTML)
dt_lb <- data.frame(
Item = c("Hello\nWorld", "This\nis a cat"),
Value = c(10, 100)
)
headers <- c("Item\n(Name)", "Value\n(Number)") %>%
stringr::str_replace_all(pattern = "\\n", replacement = "<br>")
dt_lb %>%
tableHTML(rownames = FALSE,
headers = headers,
escape = FALSE,
widths = c(100, 100),
theme = 'scientific') %>%
add_css_header(css = list(c('transform', 'height', 'text-align'),
c('rotate(-45deg)', '70px', 'center')),
headers = 1:2)
```
\
It will then create an HTML file. This file can then be converted to PDF using wkhtmltopdf.

Answer 2

I think you probably rendered your rmarkdown document into HTML... In the rmarkdown yaml header, does it say html_document right now? If so, you can try to change it to pdf_document.....
I rendered a pdf_document with exactly the same code and I think I got what you were looking for...
---
title: "Table Sample"
output: pdf_document
---
``` {r, include = FALSE}
library(tidyverse)
library(kableExtra)
```
```{r}
dt_lb <- data.frame(
Item = c("Hello\nWorld", "This\nis a cat"),
Value = c(10, 100)
)
dt_lb %>%
mutate_all(linebreak) %>%
kable("latex", booktabs = T, escape = F,
col.names = linebreak(c("Item\n(Name)", "Value\n(Number)"), align = "c")) %>%
row_spec(0, angle = 90)
```

Answer 3

Latex package makecell was missing.
Hao pointed out that Page 3 of this manual lists some of the necessary Latex packages: haozhu233.github.io/kableExtra/awesome_table_in_pdf.pdf