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DOC: update DataFrame.to_records #20191

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58 changes: 53 additions & 5 deletions pandas/core/frame.py
Original file line number Diff line number Diff line change
Expand Up @@ -1209,20 +1209,68 @@ def from_records(cls, data, index=None, exclude=None, columns=None,

def to_records(self, index=True, convert_datetime64=True):
"""
Convert DataFrame to record array. Index will be put in the
'index' field of the record array if requested
Convert DataFrame to a NumPy record array.

Index will be put in the 'index' field of the record array if
requested.

Parameters
----------
index : boolean, default True
Include index in resulting record array, stored in 'index' field
Include index in resulting record array, stored in 'index' field.
convert_datetime64 : boolean, default True
Whether to convert the index to datetime.datetime if it is a
DatetimeIndex
DatetimeIndex.

Returns
-------
y : recarray
y : numpy.recarray

See Also
--------
DataFrame.from_records: convert structured or record ndarray
to DataFrame.
numpy.recarray: ndarray that allows field access using
attributes, analogous to typed columns in a
spreadsheet.

Examples
--------
>>> df = pd.DataFrame({'A': [1, 2], 'B': [0.5, 0.75]},
... index=['a', 'b'])
>>> df
A B
a 1 0.50
b 2 0.75
>>> df.to_records()
rec.array([('a', 1, 0.5 ), ('b', 2, 0.75)],
dtype=[('index', 'O'), ('A', '<i8'), ('B', '<f8')])

The index can be excluded from the record array:

>>> df.to_records(index=False)
rec.array([(1, 0.5 ), (2, 0.75)],
dtype=[('A', '<i8'), ('B', '<f8')])

By default, timestamps are converted to `datetime.datetime`:

>>> df.index = pd.date_range('2018-01-01 09:00', periods=2, freq='min')
>>> df
A B
2018-01-01 09:00:00 1 0.50
2018-01-01 09:01:00 2 0.75
>>> df.to_records()
rec.array([(datetime.datetime(2018, 1, 1, 9, 0), 1, 0.5 ),
(datetime.datetime(2018, 1, 1, 9, 1), 2, 0.75)],
dtype=[('index', 'O'), ('A', '<i8'), ('B', '<f8')])

The timestamp conversion can be disabled so NumPy's datetime64
data type is used instead:

>>> df.to_records(convert_datetime64=False)
rec.array([('2018-01-01T09:00:00.000000000', 1, 0.5 ),
('2018-01-01T09:01:00.000000000', 2, 0.75)],
dtype=[('index', '<M8[ns]'), ('A', '<i8'), ('B', '<f8')])
"""
if index:
if is_datetime64_any_dtype(self.index) and convert_datetime64:
Expand Down