How to proper handle equations in package generated tables for PDF and HTML output?

[jm_t]

Dear community,

I am using the huxtable package to create a table. I want to have some latex equation displayed in it for html and pdf output. I have to double backslash my basic equation and disable escape_content to have the proper output.

So my questions to you are:

• How would you handle such requirements?
• If I have to keep using the double backslash version, how can I produce it from my basic tex code?

Thanks in advance for your answers and suggestions,

jm

---
title: "chap5"
output:
  pdf_document: default
  html_document: default
---

```{r setup_chap5, echo=FALSE, warning=FALSE, error=FALSE}
library(knitr)
library(dplyr)
library(huxtable)
```


## Example 1

We consider the following observations of X and Y (sample):

```{r sampleXY, echo=FALSE}

x = c(3,4,5,12)
y = c(30,70,130,210)

df = data.frame(
  xi = x,
  yi = y
)
colnames(df) <- c('x', 'y')

hx = huxtable(df, add_colnames = TRUE) %>%
  set_all_borders(row = every(), col = every(), value = 1)

# Used to test variations html vs latex & with and without escape
if (knitr::is_latex_output()) {
  hx = set_escape_contents(hx, row = c(1), col = every(), value = FALSE)
  hx = set_contents(hx, row = c(1), col = c(1), value = "latex")
  hx = set_contents(hx, row = c(1), col = c(2), value = "\\(\\alpha + \\hat{y}_i\\)")
}

if (knitr::is_html_output()) {
  hx = set_escape_contents(hx, row = c(1), col = every(), value = FALSE)
  hx = set_contents(hx, row = c(1), col = c(1), value = "html")
  hx = set_contents(hx, row = c(1), col = c(2), value = "\\(\\alpha + \\hat{y}_i\\)")  
} 

hx

```


My equation is \(\alpha + \hat{y}_i\)

```{r stringmanip, echo=TRUE, eval=FALSE}

# Does not work
str_replace_all( '\(\alpha + \hat{y}_i\)', '\', '\\'  )

# Should double in the pattern part
str_replace_all( '\(\alpha + \hat{y}_i\)', '\\', '\\\\'  )

```

[hughjonesd]

If you put your latex equations in a separate file, you could read them in as strings using readLines(). That would save you having to double all those backslashes. Example:

In equations.txt:

$\alpha^2$
$\hat{\beta}^2$

In R:

equations <- readLines("equations.txt")
hux(equations) %>% set_escape_contents(FALSE) %>% quick_pdf()

[jm_t]

Thank you for the suggestion.

I have too much equations to handle via external file. Could put them all in a kind of db file. Should work but I find that not very elegant and easy to scale up and to maintain on the long run.

jm

[hughjonesd]

Have you considered just using a standard markdown table?

[jm_t]

I have some complicated table to format for both HTML and PDF.
By complicated I mean:

• Sometimes visually not rectangular
• Generated content
• Few conditionally colored cells

Basic markdown table are ok for very basic content. I would say 6-8 cells, more than that I am lost. It is a personal opinion, there. Other people mileage will vary.

[hughjonesd]

OK. I agree you need a programmatic solution. There's no way you can write raw TeX strings in R without doubling the backslashes. So yes, you are going to need to store them externally.