Shortcut for replacing $$ $$ with align or equation?

Question

I usually use the $$ sign to do in-line equations. But often I realize I want to number it, or turn it into a sequence of aligned equations. I then manually copy and paste the equation out of the $$ $$, type \begin{ equation} and then paste the equation in. Is there a way to do this faster?

This depends on the functionalities displayed by your editor. — Bernard, Jul 08 '22 at 22:23
If your editor supports regex search, then it could be the way to go — Luis Turcio, Jul 08 '22 at 22:24
You really shouldn't be using $$ in a LaTeX document to begin with. Please see the posting Why is \[ ... \] preferable to $$ ... $$? for more information on this subject. — Mico, Jul 08 '22 at 22:26
@Mico didn't know that! I don't understand the answer in that post, but I'll believe it. So replacing $$ $$ in my question with [ ] , is there a shortcut? — lady gaga, Jul 08 '22 at 22:39
Not with LaTeX or most editors. You could write a program in another language to replace the even and odd occurrences of $$ with \[ and \]. — John Kormylo, Jul 08 '22 at 23:09
you are asking about editing a file but have not said what editor you are using. latex itself is not really involved here — David Carlisle, Jul 08 '22 at 23:50
This answer shows how to use regular expressions (regex) in a separated website and in TeXstudio. — FHZ, Jul 09 '22 at 15:38

score 4 · Answer 1 · answered Jul 09 '22 at 14:07

You have not said what editor you are using. Any reasonable editor should be able to make that edit.

Or you could use a commandline tool such as perl.

For example if file.tex is

$$ 1=1$$
qqqq
$$
2=2
$$
qqqq
$$
2=2
+1
-1
$$

then

perl -0777 -pe 's/\$\$(.*?)\$\$/\\begin{equation}$1\\end{equation}/sg' file.tex >file2.tex

will create a file2.tex that looks like

\begin{equation} 1=1\end{equation}
qqqq
\begin{equation}
2=2
\end{equation}
qqqq
\begin{equation}
2=2
+1
-1
\end{equation}

Note I suggest writing new file rather than doing an in-place edit as it gives you a chance to check the output. (For example this one-liner is not checking mis-matched $$ that may appear in comments or macros or verbatim etc)

Shortcut for replacing $$ $$ with align or equation?

1 Answers1