Scientific formats, subscripts and superscripts in RMarkdown table (docx output) - r

Question

Let's say I have the following rmd:
---
title: "Table won't work"
author: "Exhausted student"
date: "2022/01/28"
output:
bookdown::word_document2
---
```{r table, echo=F, warning=F, message=F}
library(tidyverse)
a <- tibble(
constants = c("c", "NA", "h", "e", "H2O"),
values = c(2.998e8, 6.022e23, 6.626e-34, -1.602e-19, 18.02)
)
knitr::kable(a, digits = 35)
```
which produces this table in Word.
The Problem
I need the scientific format to use superscripts and multiply sign (i.e. 2.998 × 108), and some cells requires subscript (e.g. NA and H2O).
The final table should look like this. How can I do that?
What I've tried/would never try
huxtable package and its markdown() function: I managed to format some contents as H~2~O, then enable markdown across table by huxtable(a) %>% `markdown<-`(TRUE). Which did not recognize the syntax, and apparently would not work in forseeable future according to the author.
flextable and as_sub(): Produces right format. I pass the lables to flextable::compose(), where the labels were something like as_paragraph(list_values = list("H", as_sub("2"), "O"). The code is obviously too lengthy; plus i have to manipulate cells one-by-one. Technically still doable, but I do have tables with 100+ cells needed formatting.
Output first, format in Word later: Again, needed manipulation one-by-one. Would be an option if it would work everything out automatically.
Convincing the school bureaucrats to accept html/pdf/latex as output: this is forever an impossible option.
Format outside word then export formatted table as image: strictly forbidden in the reports.
Edit: the table works now! Great thanks to Maël's answer, but please check my own findings to see my final result:

Answer 1

You can use tildes (~) to put in subscript and carets (^) for superscripts; and use sprintf to get the expected digit format:
---
title: "Table won't work"
author: "Exhausted student"
date: "2022/01/28"
output:
bookdown::word_document2
---
```{r table, echo=F, warning=F, message=F}
library(tidyverse)
expSup <- function(x, digits=3) {
sprintf(paste0("%05.", digits, "f x 10^%d^"), x/10^floor(log10(abs(x))), floor(log10(abs(x))))
}
a <- tibble(
constants = c("c", "N~A~", "h", "e", "H~2~0"),
values = expSup(c(2.998e8, 6.022e-23, 6.626e-34, -1.602e-19, 18.02))
)
knitr::kable(a)
```

Answer 2

An option that probably falls in the no-go zone for this open issue:
Create a html document,
Insert html tags for subscripts,
Open the html file (not the viewer),
ctrl+c, then ctrl+v in your word file.
---
output: html_document
---
```{r table, echo=F, warning=F, message=F}
library(tidyverse)
library(gt)
a <- tibble(
constants = c("c", "N<sub>A</sub>", "h","e","H<sub>2</sub>O"),
values = c(2.998e8, 6.022e23, 6.626e-34, -1.602e-19, 18.02)
)
a %>%
mutate(constants = map(constants, html)) %>%
gt() %>%
fmt_scientific(values)

Answer 3

The expSup() function in Maël's answer converted the scientific formats into markdown format. For my script, I modified the function a little:
exp_sup <- function(x, digits = 3) {
sprintf(paste0("%05.", digits, "f $\\times$ 10^%d^"), x / 10^floor(log10(abs(x))), floor(log10(abs(x))))
}
I changed "f x 10^%d^" to "f $\\times$ 10^%d^", so that it displays proper multiply symbol (×).
Using the format in flextable
The format works great in Kable. However, a large portion of my workflow requires flextable to make caption/cross reference/publication style/etc. Unfortunately, although the expSup function automatically formats scientific notations into markdowns, it cannot make markdown syntax work in flextable.
However, ftExtra::colformat_md() can. Hence, by combining the modified exp_sup() function with ftExtra, I was finally able to produce an academic-looking table:
Below is the code for my final output; if you are also trying to produce reproducible academic reports with lots of tables in Word format, hope this helps!
---
title: "The tables work!"
author: "Satisfied Student"
date: "2022/01/28"
output:
bookdown::word_document2:
reference_docx: styleRef.docx
---
```{r setup, include = F}
library(easypackages)
packages(
"tidyverse",
"flextable", # This works best for my workflow
"ftExtra", # For markdown formatting work in flextable
"officer" # You can customize appearance/format/etc. of caption *prefixes*
)
knitr::opts_chunk$set(
warning = FALSE,
message = FALSE,
echo = FALSE,
# Make the table caption format definable in reference_docx styles
tab.cap.style = "Table Caption",
# Make "Table 1:" prefixes not bold
tab.cap.fp_text = fp_text_lite(bold = FALSE)
# The tab.cap settings MUST be in a separate chunk from tables
)
# Converts scientific format to markdown
exp_sup <- function(x, digits = 3) {
sprintf(paste0("%05.", digits, "f $\\times$ 10^%d^"), x / 10^floor(log10(abs(x))), floor(log10(abs(x))))
}
# The $\\times$ makes proper multiply symbols
```
```{r table}
a <- tibble(
constants = c("c", "N~A~", "h", "e", "H~2~O"),
values = c(2.998e8, 6.022e23, 6.626e-34, -1.602e-19, 18.02)
)
a %>%
mutate(values = exp_sup(values)) %>%
flextable() %>%
set_caption(
caption = "(ref:foo)", # Produces formatted caption text
style = "Table Caption"
) %>%
colformat_md() %>% # Subscript/superscript works in flextable now!
theme_booktabs() %>% # The 3-part-table used in academics
align(align = "center", part = "all") %>% #Align everything to center
set_table_properties(layout = "autofit") # Comfortable width/height every cell
```
(ref:foo) A scientifically formatted `flextable` with ^superscripts^ and ~subscripts~

Answer 4

Your code should look like this:
```
{r table, echo=F, warning=F, message=F}
library(tidyverse)
a <- tibble(
constants = c("c", "NA", "h", "e", "$H_2O$"),
values = c("$2.998 * {10^{8}}$", "$6.022 * {10^{-23}}$", "$6.626 * {10^{-34}}$", "$-1.602 * {10 ^{-19}}$", "$1.802 * {10^{1}}$")
)
knitr::kable(format = "html", a, digits = 35)
```
Which will give you the output like this: