Convert Rnw to Rmd

rnw2rmd.pl

#!/usr/bin/perl

## Based on convert.txt by Mike Love
## https://gist.github.com/mikelove/5618f935ace6e389d3fbac03224860cd

## The script ignores labels and references, un-numbered sections
## (section*), quotes and probably a couple of more. It won't deal
## with the pre-amble, bibliography and document tags either. Still
## useful, though.

## Usage:
## rnw2rmd file.Rnw > file.Rmd

use warnings;

my $filename = $ARGV[0];

open (RNW, $filename);
while (<RNW>) {
    s|\\Robject{(.+?)}|`$1`|g;
    s|\\Rcode{(.+?)}|`$1`|g;
    s|\\Rclass{(.+?)}|*$1*|g;
    s|\\Rfunction{(.+?)}|`$1`|g;
    s|\\texttt{(.+?)}|`$1`|g;
    s|\\textit{(.+?)}|*$1*|g;
    s|\\textbf{(.+?)}|**$1**|g;
    s|\\emph{(.+?)}|*$1*|g;
    s|<<|```{r |g;
    s|>>=|}|g;
    s|@|```|g;
    s|\\section{(.+?)}|# $1|g;
    s|\\subsection{(.+?)}|## $1|g;
    s|\\subsubsection{(.+?)}|### $1|g;
    s|\\Biocexptpkg{(.+?)}|`r Biocexptpkg("$1")`|g;
    s|\\Biocannopkg{(.+?)}|`r Biocannopkg("$1")`|g;
    s|\\Biocpkg{(.+?)}|`r Biocpkg("$1")`|g;
    s|\\cite{(.+?)}|[\@$1]|g;
    s|\\ref{(.+?)}|\\\@ref($1)|g;
    s|\\url{(.+?)}|<$1>|g;
    s|\\ldots|\.\.\.|g;
    s|\\label{| {#|g; ## only for sections
    print $_;
}
close (RNW);

Thanks for this useful code.
I needed to escape { and }, i.e. \{ and \}.
I removed s|@|```|g; to keep @ to access slots.
I added s|\\textsl\{(.+?)\}|*$1*|g; and s|\\verb'(.+?)'|``$1``|g;