['z+2-44', '4+55+z+88']

[['z','+','2','-','44'],['4','+','55','+','z','+','88']]

import re
lst = ['z+2-44', '4+55+z+88']
[re.findall('w+|W+', s) for s in lst]
# [['z', '+', '2', '-', '44'], ['4', '+', '55', '+', 'z', '+', '88']]

z = ['z+2-44', '4+55+z+88']

print([["".join(x) for k,x in itertools.groupby(i,str.isalnum)] for i in z])

[['z', '+', '2', '-', '44'], ['4', '+', '55', '+', 'z', '+', '88']]

l = ['z+2-44', '4+55+z+88']
print([list(filter(None, re.split(r'(w+)', i))) for i in l])

[['z', '+', '2', '-', '44'], ['4', '+', '55', '+', 'z', '+', '88']]

In [34]: lst = ['z+2-44', '4+55+z+88']

In [35]: [s.replace('+', ' + ').replace('-', ' - ').split() for s in lst]
Out[35]: [['z', '+', '2', '-', '44'], ['4', '+', '55', '+', 'z', '+', '88']]

>>> testing = 'z+2-44'
>>> testing.split('+')
['z', '2-44']
>>> testing.split('-')
['z+2', '44']

import re

>>> re.split('+|-', testing)
['z', '2', '44']

>>> re.split('[^a-zA-Z0-9]', testing)
['z', '2', '44']