expr = "(32+54)*342-(4*(3-9))"

['(', '32', '+', '54', ')', '*', '342', '-', '(', '4', '*', '(', '3', '-', '9', ')', ')']

l = list(expr)
n = ''
expr = []
try:
  for c in l:
    if c in string.digits:
      n += c
    else:
      if n != '':
        expr.append(n)
        n = ''
      expr.append(c)
finally:
  if n != '':
    expr.append(n)

>>> import re
>>> expr = "(32+54)*342-(4*(3-9))"
>>> re.split("([-()+*/])", expr)
['', '(', '32', '+', '54', ')', '', '*', '342', '-', '', '(', '4', '*', '', '(', '3', '-', '9', ')', '', ')', '']

>>> [part for part in re.split("([-()+*/])", expr) if part]
['(', '32', '+', '54', ')', '*', '342', '-', '(', '4', '*', '(', '3', '-', '9', ')', ')']

>>> [x[1] for x in tokenize.generate_tokens(StringIO.StringIO('(32+54)*342-(4*(3-9))').readline)]
['(', '32', '+', '54', ')', '*', '342', '-', '(', '4', '*', '(', '3', '-', '9', ')', ')', '']

>>> if True:
    exp=[]
    expr = "(32+54)*342-(4*(3-9))"
    flag=False
    for i in expr:
        if i.isdigit() and flag:
            exp.append(str(exp.pop(len(exp)-1))+i)
        elif i.isdigit():
            flag=True
            exp.append(i)
        else:
            flag=False
            exp.append(i)
    print(exp)


['(', '32', '+', '54', ')', '*', '342', '-', '(', '4', '*', '(', '3', '-', '9', ')', ')']
>>>