pandas to_datetime()

>>> import pandas as pd
>>> i = pd.date_range('',periods=)
>>> df = pd.DataFrame(dict(year = i.year, month = i.month, day = i.day))
>>> pd.to_datetime(df.year* + df.month* + df.day, format='%Y%m%d')
    --
    --
...
   --
   --
Length: , dtype: datetime64[ns]

>>> df = df.astype(str)
>>> pd.to_datetime(df.day + df.month + df.year, format="%d%m%Y")
    --
    --
...
   --
   --
Length: , dtype: datetime64[ns]