R markdown: How to create a table with images and text which should be knitted as PDF?

Question

I would like to include a table with 2 columns including images and text (image descriptions) in PDF report compiled with R markdown. In doing so, I have the following requirements for my table:

• width: fixed column or table width

• alignment: content alignment in columns

  • top center alignment of an image in column 1
  • top left alignment of text in column 2

• text content: is at best easy and good to read also in code

• text formatting:

  • text formatting required, at best using markdown syntax, i.e, bold
  • linebreaks required

• image path: as images are stored in a subdirectory, at best use abbreviated image paths, like

  • figpath <- "Folder/Subfolder/" and then
  • fig1 <- paste0(figpath, "image1.png")

• caption: table caption is required

• citations: adding references to the table is required, i.e., like [@R-base]

• referencing: the table elsewhere is required

In ideal, the table would look like this:

I made several attempts based on LaTex syntax, markdown syntax and R markdown syntax (with kable and kableExtra), see MWEs below. However, none of the approaches yield a satisfying result. The LaTex approach comes closest but does not allow to include citations.

The table with images should later be included in a report (thesis) compiled with huskydown, which is related to thesisdown/bookdown. Any help is greatly appreciated!

Table below summarizes my approaches, MWEs provided below (for improved LaTex MWE see reply by @samcarter)

Latex approach

YAML header:
header-includes:
  \usepackage{array}
  \newcolumntype{L}[1]{>{\raggedright\let\newline\\\arraybackslash\hspace{0pt}}m{#1}}
  \newcolumntype{C}[1]{>{\centering\let\newline\\\arraybackslash\hspace{0pt}}m{#1}}
  \newcolumntype{R}[1]{>{\raggedleft\let\newline\\\arraybackslash\hspace{0pt}}m{#1}}


\begin{table}[H]
\centering
\caption{My caption}
\begin{tabular}{@{} C{6cm} L{9cm} @{}}
\\
     \toprule
       Image & Description \\
     \toprule 
      \includegraphics[width=60mm]{Folder/Subfolder/image1.png} &
       \textbf{Lorem ipsum dolor sit amet} [@R-base] \linebreak mauris mauris sollicitudin malesuada amet.\\
      & \\
      \hline
      & \\
      \includegraphics[width=60mm]{Folder/Subfolder/image2.png} &
      \textbf{Lorem ipsum dolor} [@R-bookdown]\linebreak sit amet, mauris mauris sollicitudin malesuada amet. \
\end{tabular}
\end{table}

• Pro:

  • vertical alignment: of column 1 working somehow correctly
  • caption: easy to add
  • text formatting: linebreaks feasible with "\linebreak" (but does not work so nicely due to block text)
  • generally versatile coding of tables in LaTex

• Con:

  • vertical alignment: of column 2 not working correctly - SOLVED for LaTex and simple markdown file ONLY, NOT solved for bookdown/thesisdown
  • text content: adding text content to LaTex table is rather ugly
  • text formatting: only latex formatting works, i.e. "\textbf{}"
  • Simple markdown text formatting like **bold** (obviously) does not work in LaTex table
  • image path: can not include abbreviated image paths (SOLVED)
  • citations: do NOT work in LaTex table - NOT solved
  • referencing: how to reference the LaTex table? (SOLVED)

Markdown approach (NO SOLUTION YET)

Table: Caption of my table
<!-- Table: (\#tab:myTable-reference) Caption of my table -->

| Image | Description |
| :-------: | :----------- |
| ![](Folder/Subfolder/image1.png){#id .class height=50%} | **Image description** [@R-base]  <br/>Lorem ipsum dolor sit amet, ...          |
| ![](Folder/Subfolder/image2.png){#id .class height=50%} | **Image description** [@R-bookdown] <br/>Lorem ipsum dolor sit amet, ...           |
|                  |             |

• Pro:

  • caption: easy to add
  • vertical alignment: of column 1 working correctly
  • text formatting: simple markdown text formatting like **bold** works well
  • citations: like [@R-bookdown] work well in markdown table

• Con:

  • vertical alignment: of column 2 not working correctly
  • text content: adding text content to markdown table is rather ugly
  • text formatting: linebreaks NOT feasible with <br/>
  • image path: can not include abbreviated image paths
  • referencing: how to reference table in simple markdown file? In bookdown one can label the table with Table: (\#tab:md-table) My caption and reference it with \ref{tab:md-table}. But how about in a simple md file?

kable approach (NO SOLUTION YET)

Refer to this table with [foo] or  \@ref(tab:foo)  or \@ref(fig:foo).

(ref:foo-caption) caption
(ref:foo-scaption) short caption

```{r foo, echo=FALSE, out.width='90%', fig.align = "center", fig.cap='(ref:foo-caption)', fig.scap='(ref:foo-scaption)', results='asis'}
library(stringi)
some_text <- stri_rand_lipsum(1)
some_text <- paste("**Image description**", "[@R-bookdown]", "<br/>", some_text)
figpath <- "Folder/Subfolder/"
dat <- data.frame(
  Image = c(
    paste0("![](", figpath, "image1.png){#id .class height=120px}"),
    paste0("![](", figpath, "image2.png){#id .class height=120px}")
  ),
  Description = c(
  some_text, # TEXT IMAGE 1
  some_text  # TEXT IMAGE 2
  )
)
library(knitr)
kable(dat, format = 'pandoc')
```

• Pro:

  • vertical alignment: of column 1 is working correctly
  • text content: adding text content to kable table is rather nice
  • image path: can include abbreviated image paths
  • referencing: easy to reference with label of code chunk
  • easy coding of tables in R markdown; md code of table is nicely structured/readable
  • text formatting: simple markdown text formatting like **bold** works well
  • citations: work well in kable table

• Con:

  • width: of column 2 far too wide
  • vertical alignment: of column 2 not working correctly
  • text formatting: linebreaks NOT feasible with <br/>
  • caption: not working as usual

kableExtra approach (NO SOLUTION YET)

Refer to this table with [foo2] or  \@ref(tab:foo2)  or \@ref(fig:foo2).

(ref:foo2-caption) caption
(ref:foo2-scaption) short caption

```{r foo2, echo=FALSE, out.width='90%', fig.align = "center", fig.cap='(ref:foo2-caption)', fig.scap='(ref:foo2-scaption)', results='asis'}
library(kableExtra)
kable(dat) %>%
  kable_styling(full_width = F) %>%
  column_spec(1, width = "30em")
```

• Con:
  • width: of column 2 far too wide
  • images: do not show

I am happy to provide an Rmd file with my approaches as well as the generated PDF if of any help.

Answer 1

For your latex approach:

• vertical alignment: of column 2 not working correctly

  you get your desired alignment by combining a p column (instead of the m column you used) and a top aligned image. For the top aligned image add \usepackage[export]{adjustbox} to your header includes and ,valign=t to the image options

• image path: can not include abbreviated image paths

  Using image paths is easy with \graphicspath{{./older/Subfolder/}} in your header includes

other comments:

• using [H] as floating specifier is usually not a good idea. This basically guarantees a suboptimal image placement. Instead use [htbp] to ensure that latex find the best possible locatiosn for your image.

• don't use \toprule within the table, that's what \midrule is made for

• don't use \hline when you load the booktabs package which provides alternatives with superior spacing

---

---

\documentclass{article}

\usepackage{booktabs}
\usepackage{graphicx}
\usepackage{array}
\usepackage[export]{adjustbox}
\newcolumntype{L}[1]{>{\raggedright\arraybackslash}p{#1}}


\graphicspath{{./older/Subfolder/}}

\begin{document}

\begin{table}[htbp]
\centering
\caption{My caption}
\label{foo}
\begin{tabular}{@{} L{6cm} L{8.5cm} @{}}
     \toprule
       Image & Description \\
     \midrule 
      \includegraphics[width=60mm,valign=t]{example-image-duck} &
       \textbf{Lorem ipsum dolor sit amet} [@R-base] \linebreak mauris mauris sollicitudin malesuada amet.\\
            \midrule
      \includegraphics[width=60mm,valign=t]{example-image-duck} &
      \textbf{Lorem ipsum dolor} [@R-bookdown]\linebreak sit amet, mauris mauris sollicitudin malesuada amet. \\
      \bottomrule
\end{tabular}
\end{table}

\ref{foo}

\end{document}