Classe « DataFrame »

Méthode pandas.DataFrame.shift

Signature de la méthode shift

def shift(self, periods=1, freq=None, axis=0, fill_value=<object object at 0x7f5051439e10>) -> 'DataFrame' 

Description

shift.__doc__

Shift index by desired number of periods with an optional time `freq`.

When `freq` is not passed, shift the index without realigning the data.
If `freq` is passed (in this case, the index must be date or datetime,
or it will raise a `NotImplementedError`), the index will be
increased using the periods and the `freq`. `freq` can be inferred
when specified as "infer" as long as either freq or inferred_freq
attribute is set in the index.

Parameters
----------
periods : int
    Number of periods to shift. Can be positive or negative.
freq : DateOffset, tseries.offsets, timedelta, or str, optional
    Offset to use from the tseries module or time rule (e.g. 'EOM').
    If `freq` is specified then the index values are shifted but the
    data is not realigned. That is, use `freq` if you would like to
    extend the index when shifting and preserve the original data.
    If `freq` is specified as "infer" then it will be inferred from
    the freq or inferred_freq attributes of the index. If neither of
    those attributes exist, a ValueError is thrown.
axis : {0 or 'index', 1 or 'columns', None}, default None
    Shift direction.
fill_value : object, optional
    The scalar value to use for newly introduced missing values.
    the default depends on the dtype of `self`.
    For numeric data, ``np.nan`` is used.
    For datetime, timedelta, or period data, etc. :attr:`NaT` is used.
    For extension dtypes, ``self.dtype.na_value`` is used.

    .. versionchanged:: 1.1.0

Returns
-------
DataFrame
    Copy of input object, shifted.

See Also
--------
Index.shift : Shift values of Index.
DatetimeIndex.shift : Shift values of DatetimeIndex.
PeriodIndex.shift : Shift values of PeriodIndex.
tshift : Shift the time index, using the index's frequency if
    available.

Examples
--------
>>> df = pd.DataFrame({"Col1": [10, 20, 15, 30, 45],
...                    "Col2": [13, 23, 18, 33, 48],
...                    "Col3": [17, 27, 22, 37, 52]},
...                   index=pd.date_range("2020-01-01", "2020-01-05"))
>>> df
            Col1  Col2  Col3
2020-01-01    10    13    17
2020-01-02    20    23    27
2020-01-03    15    18    22
2020-01-04    30    33    37
2020-01-05    45    48    52

>>> df.shift(periods=3)
            Col1  Col2  Col3
2020-01-01   NaN   NaN   NaN
2020-01-02   NaN   NaN   NaN
2020-01-03   NaN   NaN   NaN
2020-01-04  10.0  13.0  17.0
2020-01-05  20.0  23.0  27.0

>>> df.shift(periods=1, axis="columns")
            Col1  Col2  Col3
2020-01-01   NaN    10    13
2020-01-02   NaN    20    23
2020-01-03   NaN    15    18
2020-01-04   NaN    30    33
2020-01-05   NaN    45    48

>>> df.shift(periods=3, fill_value=0)
            Col1  Col2  Col3
2020-01-01     0     0     0
2020-01-02     0     0     0
2020-01-03     0     0     0
2020-01-04    10    13    17
2020-01-05    20    23    27

>>> df.shift(periods=3, freq="D")
            Col1  Col2  Col3
2020-01-04    10    13    17
2020-01-05    20    23    27
2020-01-06    15    18    22
2020-01-07    30    33    37
2020-01-08    45    48    52

>>> df.shift(periods=3, freq="infer")
            Col1  Col2  Col3
2020-01-04    10    13    17
2020-01-05    20    23    27
2020-01-06    15    18    22
2020-01-07    30    33    37
2020-01-08    45    48    52