date_list = [d.strftime('%Y-%m-%d') for d in pd.date_range(start = '2011-01-29', end = '2016-06-19')] #Renaming days to dates sale.rename(columns=dict(zip(sale.columns[6:], date_list)),inplace=True) code example

Example 1: www.pd.date_range

>>> pd.date_range(start='1/1/2018', periods=5, freq='3M')
DatetimeIndex(['2018-01-31', '2018-04-30', '2018-07-31', '2018-10-31',
               '2019-01-31'],
              dtype='datetime64[ns]', freq='3M')

Example 2: www.pd.date_range

>>> pd.date_range(start='1/1/2018', periods=8)
DatetimeIndex(['2018-01-01', '2018-01-02', '2018-01-03', '2018-01-04',
               '2018-01-05', '2018-01-06', '2018-01-07', '2018-01-08'],
              dtype='datetime64[ns]', freq='D')