| Current File : //usr/local/lib64/python3.6/site-packages/pandas/core/window/expanding.py |
from textwrap import dedent
from typing import Dict, Optional
from pandas.compat.numpy import function as nv
from pandas.util._decorators import Appender, Substitution, doc
from pandas.core.window.common import WindowGroupByMixin, _doc_template, _shared_docs
from pandas.core.window.rolling import _Rolling_and_Expanding
class Expanding(_Rolling_and_Expanding):
"""
Provide expanding transformations.
Parameters
----------
min_periods : int, default 1
Minimum number of observations in window required to have a value
(otherwise result is NA).
center : bool, default False
Set the labels at the center of the window.
axis : int or str, default 0
Returns
-------
a Window sub-classed for the particular operation
See Also
--------
rolling : Provides rolling window calculations.
ewm : Provides exponential weighted functions.
Notes
-----
By default, the result is set to the right edge of the window. This can be
changed to the center of the window by setting ``center=True``.
Examples
--------
>>> df = pd.DataFrame({"B": [0, 1, 2, np.nan, 4]})
>>> df
B
0 0.0
1 1.0
2 2.0
3 NaN
4 4.0
>>> df.expanding(2).sum()
B
0 NaN
1 1.0
2 3.0
3 3.0
4 7.0
"""
_attributes = ["min_periods", "center", "axis"]
def __init__(self, obj, min_periods=1, center=None, axis=0, **kwargs):
super().__init__(obj=obj, min_periods=min_periods, center=center, axis=axis)
@property
def _constructor(self):
return Expanding
def _get_window(self, other=None, **kwargs):
"""
Get the window length over which to perform some operation.
Parameters
----------
other : object, default None
The other object that is involved in the operation.
Such an object is involved for operations like covariance.
Returns
-------
window : int
The window length.
"""
axis = self.obj._get_axis(self.axis)
length = len(axis) + (other is not None) * len(axis)
other = self.min_periods or -1
return max(length, other)
_agg_see_also_doc = dedent(
"""
See Also
--------
pandas.DataFrame.aggregate : Similar DataFrame method.
pandas.Series.aggregate : Similar Series method.
"""
)
_agg_examples_doc = dedent(
"""
Examples
--------
>>> df = pd.DataFrame({"A": [1, 2, 3], "B": [4, 5, 6], "C": [7, 8, 9]})
>>> df
A B C
0 1 4 7
1 2 5 8
2 3 6 9
>>> df.ewm(alpha=0.5).mean()
A B C
0 1.000000 4.000000 7.000000
1 1.666667 4.666667 7.666667
2 2.428571 5.428571 8.428571
"""
)
@doc(
_shared_docs["aggregate"],
see_also=_agg_see_also_doc,
examples=_agg_examples_doc,
versionadded="",
klass="Series/Dataframe",
axis="",
)
def aggregate(self, func, *args, **kwargs):
return super().aggregate(func, *args, **kwargs)
agg = aggregate
@Substitution(name="expanding")
@Appender(_shared_docs["count"])
def count(self, **kwargs):
return super().count(**kwargs)
@Substitution(name="expanding")
@Appender(_shared_docs["apply"])
def apply(
self,
func,
raw: bool = False,
engine: Optional[str] = None,
engine_kwargs: Optional[Dict[str, bool]] = None,
args=None,
kwargs=None,
):
return super().apply(
func,
raw=raw,
engine=engine,
engine_kwargs=engine_kwargs,
args=args,
kwargs=kwargs,
)
@Substitution(name="expanding")
@Appender(_shared_docs["sum"])
def sum(self, *args, **kwargs):
nv.validate_expanding_func("sum", args, kwargs)
return super().sum(*args, **kwargs)
@Substitution(name="expanding", func_name="max")
@Appender(_doc_template)
@Appender(_shared_docs["max"])
def max(self, *args, **kwargs):
nv.validate_expanding_func("max", args, kwargs)
return super().max(*args, **kwargs)
@Substitution(name="expanding")
@Appender(_shared_docs["min"])
def min(self, *args, **kwargs):
nv.validate_expanding_func("min", args, kwargs)
return super().min(*args, **kwargs)
@Substitution(name="expanding")
@Appender(_shared_docs["mean"])
def mean(self, *args, **kwargs):
nv.validate_expanding_func("mean", args, kwargs)
return super().mean(*args, **kwargs)
@Substitution(name="expanding")
@Appender(_shared_docs["median"])
def median(self, **kwargs):
return super().median(**kwargs)
@Substitution(name="expanding", versionadded="")
@Appender(_shared_docs["std"])
def std(self, ddof=1, *args, **kwargs):
nv.validate_expanding_func("std", args, kwargs)
return super().std(ddof=ddof, **kwargs)
@Substitution(name="expanding", versionadded="")
@Appender(_shared_docs["var"])
def var(self, ddof=1, *args, **kwargs):
nv.validate_expanding_func("var", args, kwargs)
return super().var(ddof=ddof, **kwargs)
@Substitution(name="expanding", func_name="skew")
@Appender(_doc_template)
@Appender(_shared_docs["skew"])
def skew(self, **kwargs):
return super().skew(**kwargs)
_agg_doc = dedent(
"""
Examples
--------
The example below will show an expanding calculation with a window size of
four matching the equivalent function call using `scipy.stats`.
>>> arr = [1, 2, 3, 4, 999]
>>> import scipy.stats
>>> print(f"{scipy.stats.kurtosis(arr[:-1], bias=False):.6f}")
-1.200000
>>> print(f"{scipy.stats.kurtosis(arr, bias=False):.6f}")
4.999874
>>> s = pd.Series(arr)
>>> s.expanding(4).kurt()
0 NaN
1 NaN
2 NaN
3 -1.200000
4 4.999874
dtype: float64
"""
)
@Appender(_agg_doc)
@Substitution(name="expanding")
@Appender(_shared_docs["kurt"])
def kurt(self, **kwargs):
return super().kurt(**kwargs)
@Substitution(name="expanding")
@Appender(_shared_docs["quantile"])
def quantile(self, quantile, interpolation="linear", **kwargs):
return super().quantile(
quantile=quantile, interpolation=interpolation, **kwargs
)
@Substitution(name="expanding", func_name="cov")
@Appender(_doc_template)
@Appender(_shared_docs["cov"])
def cov(self, other=None, pairwise=None, ddof=1, **kwargs):
return super().cov(other=other, pairwise=pairwise, ddof=ddof, **kwargs)
@Substitution(name="expanding")
@Appender(_shared_docs["corr"])
def corr(self, other=None, pairwise=None, **kwargs):
return super().corr(other=other, pairwise=pairwise, **kwargs)
class ExpandingGroupby(WindowGroupByMixin, Expanding):
"""
Provide a expanding groupby implementation.
"""
@property
def _constructor(self):
return Expanding