[Tex/LaTex] Automatically replace all |foo| with \abs{foo}

editorsmath-modescripts

Technically speaking, this isn't a LaTeX specific question, but there are so many useful tools in LaTeX, and I'm using it to solve a LaTeX problem, so I thought here would be a good place to ask.

I have a rather large document with lots of math notation. I've used |foo| throughout to indicate the absolute value of foo. I'd like to replace every instance of |foo| with \abs{foo}, so that I can control the notation via an abs macro I define.

Does anybody know of a way to do this? Possibly using regular expressions of some sort? Are there editors with tools built in for this?

Best Answer

Option 1: `sed`

The stream editing tool, sed, would be a natural first choice, but the problem is that sed can't match non-greedy regular expressions.

We need a non-greedy regular expression here- to clarify why, let's consider

sed -r 's/|(.*)|/\\abs{\1}/g' myfile.tex

If we apply this substitution to a file that contains something like

$|a|+|b|\geq|a+b|$

then we'll get

$\abs{a|+|b|\geq|a+b}$

which is clearly not what we want- regular expression matches like this are greedy by default.

To make it non-greedy, we typically use .*?, but the problem is that sed does not support this type of match. Happily (thanks Hendrik) we can use the following instead

sed -r 's/\|([^|]*)\|/\\abs{\1}/g' myfile.tex

Once you're comfortable that it does what you want, you can use

sed -ri.bak 's/\|([^|]*)\|/\\abs{\1}/g' myfile.tex

which will overwrite each file, and make a back up first, myfile.tex.bak

Option 2: `perl`

We could, instead, use a little perl one-liner:

perl -pe 's/\|(.*?)\|/\\abs{\1}/g' myfile.tex

When you're sure that you trust it is working correctly, you can use the following to overwrite myfile.tex

perl -pi -e 's/\|(.*?)\|/\\abs{\1}/g' myfile.tex

You can replace myfile.tex with, for example, *.tex to operate on all the .tex files in the current working directory.

Details of perl's switches are discussed here (for example): http://perldoc.perl.org/perlrun.html#Command-Switches

Related Solutions

[Tex/LaTex] Latex: Nice abs

TeX also offers a primitive parameter to always make delimiters grow.

\documentclass{article}
\delimitershortfall-1sp
\newcommand\abs[1]{\left|#1\right|}
\begin{document}
\[
\abs{ x-\abs{ x-\abs{x-4}}}
\]
\end{document}

gives the desired output.

enter image description here

\delimitershortfall is meant to measure how much larger the content is allowed to get before the delimiters start growing, but by setting it to a negative value delimiters always grow.

[Tex/LaTex] How to replace all $ $ by 

Here's a perl script to get you started, subDollars.pl. As a disclaimer, you should test it significantly before using it on anything important. I can't guarantee the results, but it should get you started.

You can use it in the following way

perl subDollars.pl test.tex will simply output to the terminal with the substitutions
perl subDollars.pl -s test.tex will not output to the terminal
perl subDollars.pl -w test.tex will overwrite test.tex with the substitutions in place
perl subDollars.pl -o test.tex output.tex will output to output.tex with the substitutions in place.

Any environments that you don't want it to operate on should be included in

my %nosubstitutions = ("tikzpicture"=>1, "verbatim"=>1, "nosubblock"=>1);

This hash can consist of stand environments such as tikzpicture

\begin{tikzpicture}
\draw[red] ($(#2)+(-.5em,.9em)$) rectangle ($(RightPoint)+(0.2em,-0.3em)$);
\end{tikzpicture}

or any blocks of code that are not necessarily within an environment, but you can wrap them in a 'commented' environment, such as

%\begin{nosubblock}
\draw[red] ($(#2)+(-.5em,.9em)$) rectangle ($(RightPoint)+(0.2em,-0.3em)$);
%\end{nosubblock}

The script won't account for $...$ and $$...$$ split across lines- that's certainly doable, but a little more work.

`subDollars.pl`

#!/usr/bin/perl

use strict;
use warnings;           
use File::Copy;         # to copy the original file to backup (if overwrite option set)
use Getopt::Std;        # to get the switches/options/flags

# get the options
my %options=();
getopts("wos", \%options);

# standard output
my $out = *STDOUT;

# overwrite option
my $overwrite = 0;
$overwrite = $options{w};

# output file option
my $outputToFile = $options{o};

# can't call the script with MORE THAN 2 files
if(scalar(@ARGV)>2)
{
print $out <<ENDQUOTE

ERROR:
\t You're calling subDollars.pl with more than two file names
\t The script can take at MOST two file names, but you 
\t need to call it with the -o switch; for example

\t subDollars.pl -o originalfile.tex outputfile.tex

Exiting...
ENDQUOTE
;
    exit(2);
}

# check for output file
if($outputToFile and scalar(@ARGV)==1)
{
print $out <<ENDQUOTE
ERROR: When using the -o flag you need to call this script with 2 arguments

subDollars.pl -o "$ARGV[0]" [needs another name here]

Exiting...
ENDQUOTE
;
    exit(2);
}

# don't call the script with 2 files unless the -o flag is active
if(!$outputToFile and scalar(@ARGV)==2)
{
print $out <<ENDQUOTE

ERROR:
\t You're calling subDollars.pl with two file names, but not the -o flag.
\t Did you mean to use the -o flag ?

Exiting...
ENDQUOTE
;
    exit(2);
}

# array to store the modified lines
my @lines;

# hash naming environments that contain lines 
# that should not be substituted
my %nosubstitutions = ("tikzpicture"=>1, "verbatim"=>1, "nosubblock"=>1);

# switch to toggle nosubstitutions- initially off
my $nosubs = 0;

# if we want to over write the current file
# create a backup first
if ($overwrite)
{
    # original name of file
    my $filename = $ARGV[0];
    # copy it
    my $backupFile = $filename;
    my $backupExtension='.bak';

    $backupFile =~ s/\.tex/$backupExtension/;

    copy($filename,$backupFile) or die "Could not write to backup file $backupFile. Please check permissions. Exiting.\n";
}

# open the file
open(MAINFILE, $ARGV[0]) or die "Could not open input file";

# loop through the lines in the INPUT file
while(<MAINFILE>)
{
    # check for BEGIN of an environment that doesn't want substitutions
    $nosubs = 1 if( $_ =~ m/^\s*\\begin{(.*?)}/ and $nosubstitutions{$1} );

    # check for %\begin{nosubblock}
    $nosubs = 1 if( $_ =~ m/^\s*%\s*\\begin{(.*?)}/ and $nosubstitutions{$1} );

    # check for END of an environment that doesn't want substitutions
    $nosubs = 0 if( $_ =~ m/^\s*\\end{(.*?)}/ and $nosubstitutions{$1});

    # check for %\end{nosubblock}
    $nosubs = 0 if( $_ =~ m/^\s*%\s*\\end{(.*?)}/ and $nosubstitutions{$1} );

    # substitute $.*$ with \(.*\) 
    # note: this does NOT match $$.*$$
    s/(?<!\$)\$([^\$].*?)\$/\\\($1\\\)/g unless($nosubs);

    # substitute $$.*$$ with \[.*\]
    s/\$\$(.*?)\$\$/\\\[$1\\\]/g unless($nosubs);

    push(@lines,$_);

}

# output the formatted lines to the terminal
print @lines if(!$options{s});

# if -w is active then output to $ARGV[0]
if($overwrite)
{
    open(OUTPUTFILE,">",$ARGV[0]);
    print OUTPUTFILE @lines;
    close(OUTPUTFILE);
}

# if -o is active then output to $ARGV[1]
if($outputToFile)
{
    open(OUTPUTFILE,">",$ARGV[1]);
    print OUTPUTFILE @lines;
    close(OUTPUTFILE);
}

exit;

Here's a test file to test it on

`before.tex`

\documentclass{article}

\begin{document}

$x=a+b$

$x=a+b$ and another $x=a+b$, $x=a+b$ and another $x=a+b$

$$x=a+b$$ and another $$x=a+b$$, $$x=a+b$$ and another $$x=a+b$$

\begin{tikzpicture}
\draw[red] ($(#2)+(-.5em,.9em)$) rectangle ($(RightPoint)+(0.2em,-0.3em)$);
\end{tikzpicture}

\begin{verbatim}
\draw[red] ($(#2)+(-.5em,.9em)$) rectangle ($(RightPoint)+(0.2em,-0.3em)$);
\end{verbatim}

$$x=a+b$$ and another $$x=a+b$$, $$x=a+b$$ and another $$x=a+b$$

%\begin{nosubblock}
\draw[red] ($(#2)+(-.5em,.9em)$) rectangle ($(RightPoint)+(0.2em,-0.3em)$);
%\end{nosubblock}

$x=a+b$ and another $x=a+b$, $x=a+b$ and another $x=a+b$

$$x=a+b$$ and another $$x=a+b$$, $$x=a+b$$ and another $$x=a+b$$
\end{document}

`after.tex`

\documentclass{article}

\begin{document}

\(x=a+b\)

\(x=a+b\) and another \(x=a+b\), \(x=a+b\) and another \(x=a+b\)

\[x=a+b\] and another \[x=a+b\], \[x=a+b\] and another \[x=a+b\]

\begin{tikzpicture}
\draw[red] ($(#2)+(-.5em,.9em)$) rectangle ($(RightPoint)+(0.2em,-0.3em)$);
\end{tikzpicture}

\begin{verbatim}
\draw[red] ($(#2)+(-.5em,.9em)$) rectangle ($(RightPoint)+(0.2em,-0.3em)$);
\end{verbatim}

\[x=a+b\] and another \[x=a+b\], \[x=a+b\] and another \[x=a+b\]

%\begin{nosubblock}
\draw[red] ($(#2)+(-.5em,.9em)$) rectangle ($(RightPoint)+(0.2em,-0.3em)$);
%\end{nosubblock}

\(x=a+b\) and another \(x=a+b\), \(x=a+b\) and another \(x=a+b\)

\[x=a+b\] and another \[x=a+b\], \[x=a+b\] and another \[x=a+b\]
\end{document}

Best Answer

Option 1: sed

Option 2: perl

Related Solutions

[Tex/LaTex] Latex: Nice abs

[Tex/LaTex] How to replace all $ $ by \( \)

subDollars.pl

before.tex

after.tex

Related Question

Option 1: `sed`

Option 2: `perl`

`subDollars.pl`

`before.tex`

`after.tex`