If you have imported "re", then re.split() will work:
import re
s=' 1 , 2 , , , 3 '
print ([el for el in re.split(r"[, ]+",s) if el])
['1', '2', '3']
If strings separated by only spaces (with no intervening comma) should not be separated, then this will work:
import re
s=' ,,,,, ,,,, 1 , 2 , , , 3,,,,,4 5, 6 '
print ([el for el in re.split(r"\s*,\s*",s.strip()) if el])
['1', '2', '3', '4 5', '6']
