python/pandas: convert month int to month name

Since the abbreviated month names is the first three letters of their full names, we could first convert the Month column to datetime and then use dt.month_name() to get the full month name and finally use str.slice() method to get the first three letters, all using pandas and only in one line of code:

df['Month'] = pd.to_datetime(df['Month'], format='%m').dt.month_name().str.slice(stop=3)

df

  Month client
0   Feb sss
1   Dec yyy
2   Jun www

You can do this efficiently with combining calendar.month_abbr and df[col].apply()

import calendar
df['Month'] = df['Month'].apply(lambda x: calendar.month_abbr[x])