import re
s = "one two 3.4 5,6 seven.eight nine,ten,1.2,a,5"
print re.split('\s|(?<!\d)[,.]|[,.](?!\d)', s)
aW1wb3J0IHJlCgpzID0gIm9uZSB0d28gMy40IDUsNiBzZXZlbi5laWdodCBuaW5lLHRlbiwxLjIsYSw1IgpwcmludCByZS5zcGxpdCgnXHN8KD88IVxkKVssLl18WywuXSg/IVxkKScsIHMp
['one', 'two', '3.4', '5,6', 'seven', 'eight', 'nine', 'ten', '1.2', 'a', '5']