RMarkdown kable vertically align cells

7
votes

I am authoring a report using RMarkdown, and using kable and kableExtra to format and print the table. Here is what I want would look like the table to look like (made in Word):

Middle Cell Alignment

I am struggling to sort the vertical centering (the space between "Number of Incident Occurences" on the top and bottom, so that the text is aligned in the middle of the row, left on the column.

Note, I am creating a PDF report and not html.

Here is a minimal example:

df <- data.frame(a = letters[1:5], b = 1:5)
names(df) <- c("A very very very very very very very very very very very very very very very very very very long title",
               "A short title")

df %>% kable(format = 'latex', linesep = "", align = 'c', escape = F) %>% kable_styling(full_width = T)

This what that output looks like:

enter image description here

The vertical alignment seems to be pushing to the top. I came across "m", but that just middle aligns the columns. I'm wondering if I need to specify something special is row_spec() for all rows for align = "m", but when I do that, it complains.... Any ideas?

2
latexr-markdownkablekableextra
Try and be as concise as possible: it makes it easier to help. I've edited the question and also included a reproducible example. - Michael Harper
Possible duplicate of Vertical align kable's column name - Michael Harper
@MikeyHarper - Thank you for the edit, I will keep this in mind for future posts. - azdatasci
Great, I always prefer editing posts to show how they could be improved. Also, you may want to check out this: rprogramming.net/rename-columns-in-r In your original code you were renaming all the columns separately which is a long-winded way of doing it. Just rename them all with a list - Michael Harper
@MikeyHarper - I did lots of searching for this both in SO and in Google, and never saw that post. Thanks for the example - looks like the same thing to me. Not sure how I never came across that one in my 2 days of searching. - azdatasci

2 Answers

8
votes

This can be easily achieved in HTML by adding the extra_css argument. (for those who are searching for a similar solution in HTML and are only finding this post)

column_spec(1,extra_css = "vertical- align:middle;")
6
votes

There doesn't seem to be a way to do this directly within kable and kableExtra. However, as when building a table to PDF through kable, it uses LaTeX to build the result. We can therefore integrate LaTeX functions directly into the table.

This solution uses the multirow package. The cell to be centered vertically can be wrapped in \\multirow{1}{*}[0pt]{Cell content}, as follows:

---
header-includes:
  - \usepackage{multirow}
output: pdf_document
---

```{r}
library(knitr)
library(kableExtra)

df <- data.frame(a = letters[1:5], b = 1:5)
names(df) <- c("A very very very very very very very very very very very very very very very very very very long title",
               "\\multirow{1}{*}[0pt]{A short title}")


df %>% kable(format = 'latex', linesep = "", align = 'c', escape = F) %>% kable_styling(full_width = T)
```

enter image description here

To make using this easier, you could make a function to do the renaming for you:

centerText <- function(text){
    paste0("\\multirow{1}{*}[0pt]{", text, "}")
  }

So to rename a column you run: centerText("A short title")