s = pd.Series(['a', 'b', 'c']) s.str.cat([1, 2, 3]) 

Traceback (most recent call last): File "<stdin>", line 1, in <module> File "C:\Users\Axel Obermeier\eclipse-workspace\pddev\pandas\core\strings.py", line 2222, in cat res = str_cat(data, others=others, sep=sep, na_rep=na_rep) File "C:\Users\Axel Obermeier\eclipse-workspace\pddev\pandas\core\strings.py", line 111, in str_cat cats = [sep.join(tup) for tup in tuples] File "C:\Users\Axel Obermeier\eclipse-workspace\pddev\pandas\core\strings.py", line 111, in <listcomp> cats = [sep.join(tup) for tup in tuples] TypeError: sequence item 1: expected str instance, int found