get list of pandas dataframe columns based on data type

If I have a dataframe with the following columns:

    1. NAME                                     object
    2. On_Time                                      object
    3. On_Budget                                    object
    4. %actual_hr                                  float64
    5. Baseline Start Date                  datetime64[ns]
    6. Forecast Start Date                  datetime64[ns]

I would like to be able to say: here is a dataframe, give me a list of the columns which are of type Object or of type DateTime?

I have a function which converts numbers (Float64) to two decimal places, and I would like to use this list of dataframe columns, of a particular type, and run it through this function to convert them all to 2dp.

Maybe:

    For c in col_list: if c.dtype = "Something"
    list[]
    List.append(c)?

If you want a list of columns of a certain type, you can use groupby:

    >>> df = pd.DataFrame([[1, 2.3456, 'c', 'd', 78]], columns=list("ABCDE"))
    >>> df
       A       B  C  D   E
    0  1  2.3456  c  d  78

    [1 rows x 5 columns]
    >>> df.dtypes
    A      int64
    B    float64
    C     object
    D     object
    E      int64
    dtype: object
    >>> g = df.columns.to_series().groupby(df.dtypes).groups
    >>> g
    {dtype('int64'): ['A', 'E'], dtype('float64'): ['B'], dtype('O'): ['C', 'D']}
    >>> {k.name: v for k, v in g.items()}
    {'object': ['C', 'D'], 'int64': ['A', 'E'], 'float64': ['B']}

From: stackoverflow.com/q/22470690

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