In [21]: def func(string): a_new_string =string.replace('- ','_') a_new_string1 =a_new_string.replace('-','_') a_new_string2= a_new_string1.rstrip(' months') return a_new_string2 df['Time'] = df['Time'].apply(func) df Out[21]: Time 0 2_3 1 1_2 2 10_11 3 4_5