import pandas as pd df = pd.DataFrame({'A': [1, None, 'hello', True, 'world', 'mystr', 34.11]}) df['stringy'] = [isinstance(x, str) for x in df.A] # A stringy # 0 1 False # 1 None False # 2 hello True # 3 True False # 4 world True # 5 mystr True # 6 34.11 False