Python Regex To Simplify LaTex Fractions

This is my python program: def fractionSimplifier(content): content.replace('\\dfrac','\\frac') pat = re.compile('\\frac\{(.*?)\}\{\\frac\{(.*?)\}\{(.*?)\}\}') match =

Solution 1:

A few issues here.

1. pat.match checks only at the beginning of the string. You want pat.search there.

2. In re.compile command you escape {} which is unnecessary, and do not escape backslashes enough. As written, \\f inside string quotes is understood as \f, which then is understood as a control character by re library. Either put four backslashes \\\\f or, better, use raw string input (explained here):

re.compile(r'\\frac{(.*?)}{\\frac{(.*?)}{(.*?)}}')

3. .format(*match.group()) should be .format(*match.groups())

With the above changes, it works somewhat: the output for your "Chebyshev of second kind" example is

 \frac{(\ChebyU{\ell}@{x})^2*2}{\pi} 

as intended.

Additional remarks:

• Your code doesn't deal with multiple matches at present
• You have no code for substituting expr back into the original string in place of the match
• Instead of asterisk, in LaTeX one uses \cdot
• Parsing complex math formulas with regex is generally a bad idea.