Changing certain column type to date from datetime-CodePudding

I have a df in which I want to change certain columns type to date from datetime:

field   category    2022-01-10 00:00:00     2022-01-17 00:00:00     2022-01-24 00:00:00
A       10          500                     700                     500
B       15          60                      70                      50

I am trying to achieve this:

field   category    2022-01-10      2022-01-17      2022-01-24
A       10          500             700             500
B       15          60              70              50

Because during concat with other df the column type changes from 2021-11-19 to 2021-11-19 00:00:00.

From this answer I tried::

df.loc[:,pd.to_datetime('2022-01-10 00:00:00') : pd.to_datetime('2022-06-20 00:00:00')].columns = 
                                                 pd.to_datetime(df.loc[:,pd.to_datetime('2022-01-10 00:00:00') : 
                                                 pd.to_datetime('2022-06-20 00:00:00')].columns)
                                                 .strftime('%Y-%m-%d')

But this does not change the type of the column which I cant understand why because

pd.to_datetime(df.loc[:,pd.to_datetime('2022-01-10 00:00:00') : pd.to_datetime('2022-06-20 00:00:00')].columns).strftime('%Y-%m-%d')

Return:

Index(['2022-01-10', '2022-01-17', '2022-01-24')]

CodePudding user response：

In your column index you mix string ('field' and 'category') and timestamp (other columns) so your column index is an Index not a DatetimeIndex.

>>> df.columns
Index([            'field',          'category', 2022-01-10 00:00:00,
       2022-01-17 00:00:00, 2022-01-24 00:00:00],
      dtype='object')

>>> [type(c) for c in df.columns]
[str,
 str,
 pandas._libs.tslibs.timestamps.Timestamp,
 pandas._libs.tslibs.timestamps.Timestamp,
 pandas._libs.tslibs.timestamps.Timestamp]

The default string representation of Timestamp is YYYY-mm-dd HH:MM:SS while the default representation of each value of a DatetimeIndex can be YYYY-mm-dd only (if possible).

To get the date format, you have to cast your Timestamp to string.

CodePudding user response：

Given that, the specific column type is datetime. You can use the dt.date from pandas to keep only the date. Please, look at the example below.

dates_only = df["datetime"].dt.date