Fixing tilde inserted in latex

[brry]

This is a comment to #492 (Code chunks with a formula as in lm(y~x) are typeset as a "high" tilde instead of a "middle" tilde) and may be closed at will:

In the .Rnw LaTeX preamble, I add

\usepackage{textcomp} % enable middle tilde 
\newcommand{\tildemid}{\raisebox{0.5ex}{\texttildelow}}

Then in the setup chunk, I add

knitr::knit_hooks$set(source = function(x, options) {
  out <- knitr::hooks_latex()$source(x, options)
  gsub("~","\\\\tildemid", out)
  })

To avoid a textcomp dependency, I also tried

gsub("\\hlopt{~} ","\\sim", out)

which looks really nice, but generates missing $ inserted errors.
I chose to not further pursue that road but use the first solution.

[yihui]

which looks really nice, but generates missing $ inserted errors.

I don't understand---if it throws an error, how did you get the PDF output that looked nice? It seems you need $\\sim$?

[brry]

I don't know how that worked while generating errors.
$\\sim$ displayed the dollar signs in the code chunk. Same with \\$\\sim\\$.
Both still produced error messages.

I'm absolutely happy with the \tildemid solution.
As for me, this issue can be closed, as long as a reference shows up in #492 in case someone else lands there in the future.

[yihui]

Let me rethink about it (darn it I have completely forgotten that it was @jaredlander who filed #492---he is my VIP). Thanks for filing the issue again!

[jaredlander]

And you're my MVP

[yihui]

I just provide a package option to allow for customizing the tilde symbol. Two examples:

Using \texttildelow in textcomp

\documentclass{article}
\usepackage{textcomp} % enable middle tilde
\newcommand{\tildemid}{\raisebox{0.5ex}{\texttildelow}}
\begin{document}

<<setup, include=FALSE>>=
knitr::opts_knit$set(latex.tilde = r"(\hlopt{\tildemid})")
@

<<>>=
y ~ x
@
\end{document}

Using the math symbol \sim

\documentclass{article}
\begin{document}

<<setup, include=FALSE>>=
knitr::opts_knit$set(latex.tilde = r"(\hlopt{\scriptsize{\ensuremath{\sim}}})")
@

<<>>=
y ~ x
@
\end{document}

The output of the second example looks better in my eyes, but keep in mind that the symbol is actually not a tilde, so you won't be able to copy the code and run it.

As I mentioned in #492, this is a surprisingly complicated task: https://tex.stackexchange.com/q/312/9128 I can't provide a good default (ideally the correct ~ character with no extra dependency, which seems to be impossible), and will let you decide which solution you want to adopt.

[github-actions]

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