用python中的正则表达式匹配数学表达式

Question

I am unfortunately pretty unfamiliar to regular expressions. At the moment I try to replace some mathematical functions of the form a**b with pow(a, b) . Here is an example:

import re 
s = "8*pi**3*sin(x3)*sin(pi*z)**2" 
r = "[^*]\w*[*][*]\d"

This approach leads to:

In [64]: re.findall(r, s)
Out[64]: ['pi**3', ')**2']

So in the second case the * inside the sin function is the end of the match, but it should be 'sin(pi*z)**2' . I am not sure how to ignore the * inside the brackets. Thank you for any suggestions

Answer 1

Instead of using regex this can be solved by using the sympy ccode function for example:

from sympy.printing import ccode
from sympy.parsing.sympy_parser import parse_expr

s = "8*pi**3*sin(x3)*sin(pi*z)**2" 
exp = parse_expr(s)

In [55]: ccode(exp) 
Out[55]: '8*pow(M_PI, 3)*sin(x3)*pow(sin(M_PI*z), 2)'