AIM-PIbd-32-Kurbanova-A-A/aimenv/Lib/site-packages/statsmodels/graphics/tsaplots.py
2024-10-02 22:15:59 +04:00

874 lines
28 KiB
Python

"""Correlation plot functions."""
from statsmodels.compat.pandas import deprecate_kwarg
import calendar
import numpy as np
import pandas as pd
from statsmodels.graphics import utils
from statsmodels.tools.validation import array_like
from statsmodels.tsa.stattools import acf, pacf, ccf
def _prepare_data_corr_plot(x, lags, zero):
zero = bool(zero)
irregular = False if zero else True
if lags is None:
# GH 4663 - use a sensible default value
nobs = x.shape[0]
lim = min(int(np.ceil(10 * np.log10(nobs))), nobs // 2)
lags = np.arange(not zero, lim + 1)
elif np.isscalar(lags):
lags = np.arange(not zero, int(lags) + 1) # +1 for zero lag
else:
irregular = True
lags = np.asanyarray(lags).astype(int)
nlags = lags.max(0)
return lags, nlags, irregular
def _plot_corr(
ax,
title,
acf_x,
confint,
lags,
irregular,
use_vlines,
vlines_kwargs,
auto_ylims=False,
skip_lag0_confint=True,
**kwargs,
):
if irregular:
acf_x = acf_x[lags]
if confint is not None:
confint = confint[lags]
if use_vlines:
ax.vlines(lags, [0], acf_x, **vlines_kwargs)
ax.axhline(**kwargs)
kwargs.setdefault("marker", "o")
kwargs.setdefault("markersize", 5)
if "ls" not in kwargs:
# gh-2369
kwargs.setdefault("linestyle", "None")
ax.margins(0.05)
ax.plot(lags, acf_x, **kwargs)
ax.set_title(title)
ax.set_ylim(-1, 1)
if auto_ylims:
ax.set_ylim(
1.25 * np.minimum(min(acf_x), min(confint[:, 0] - acf_x)),
1.25 * np.maximum(max(acf_x), max(confint[:, 1] - acf_x)),
)
if confint is not None:
if skip_lag0_confint and lags[0] == 0:
lags = lags[1:]
confint = confint[1:]
acf_x = acf_x[1:]
lags = lags.astype(float)
lags[np.argmin(lags)] -= 0.5
lags[np.argmax(lags)] += 0.5
ax.fill_between(
lags, confint[:, 0] - acf_x, confint[:, 1] - acf_x, alpha=0.25
)
@deprecate_kwarg("unbiased", "adjusted")
def plot_acf(
x,
ax=None,
lags=None,
*,
alpha=0.05,
use_vlines=True,
adjusted=False,
fft=False,
missing="none",
title="Autocorrelation",
zero=True,
auto_ylims=False,
bartlett_confint=True,
vlines_kwargs=None,
**kwargs,
):
"""
Plot the autocorrelation function
Plots lags on the horizontal and the correlations on vertical axis.
Parameters
----------
x : array_like
Array of time-series values
ax : AxesSubplot, optional
If given, this subplot is used to plot in instead of a new figure being
created.
lags : {int, array_like}, optional
An int or array of lag values, used on horizontal axis. Uses
np.arange(lags) when lags is an int. If not provided,
``lags=np.arange(len(corr))`` is used.
alpha : scalar, optional
If a number is given, the confidence intervals for the given level are
returned. For instance if alpha=.05, 95 % confidence intervals are
returned where the standard deviation is computed according to
Bartlett's formula. If None, no confidence intervals are plotted.
use_vlines : bool, optional
If True, vertical lines and markers are plotted.
If False, only markers are plotted. The default marker is 'o'; it can
be overridden with a ``marker`` kwarg.
adjusted : bool
If True, then denominators for autocovariance are n-k, otherwise n
fft : bool, optional
If True, computes the ACF via FFT.
missing : str, optional
A string in ['none', 'raise', 'conservative', 'drop'] specifying how
the NaNs are to be treated.
title : str, optional
Title to place on plot. Default is 'Autocorrelation'
zero : bool, optional
Flag indicating whether to include the 0-lag autocorrelation.
Default is True.
auto_ylims : bool, optional
If True, adjusts automatically the y-axis limits to ACF values.
bartlett_confint : bool, default True
Confidence intervals for ACF values are generally placed at 2
standard errors around r_k. The formula used for standard error
depends upon the situation. If the autocorrelations are being used
to test for randomness of residuals as part of the ARIMA routine,
the standard errors are determined assuming the residuals are white
noise. The approximate formula for any lag is that standard error
of each r_k = 1/sqrt(N). See section 9.4 of [1] for more details on
the 1/sqrt(N) result. For more elementary discussion, see section
5.3.2 in [2].
For the ACF of raw data, the standard error at a lag k is
found as if the right model was an MA(k-1). This allows the
possible interpretation that if all autocorrelations past a
certain lag are within the limits, the model might be an MA of
order defined by the last significant autocorrelation. In this
case, a moving average model is assumed for the data and the
standard errors for the confidence intervals should be
generated using Bartlett's formula. For more details on
Bartlett formula result, see section 7.2 in [1].
vlines_kwargs : dict, optional
Optional dictionary of keyword arguments that are passed to vlines.
**kwargs : kwargs, optional
Optional keyword arguments that are directly passed on to the
Matplotlib ``plot`` and ``axhline`` functions.
Returns
-------
Figure
If `ax` is None, the created figure. Otherwise the figure to which
`ax` is connected.
See Also
--------
matplotlib.pyplot.xcorr
matplotlib.pyplot.acorr
Notes
-----
Adapted from matplotlib's `xcorr`.
Data are plotted as ``plot(lags, corr, **kwargs)``
kwargs is used to pass matplotlib optional arguments to both the line
tracing the autocorrelations and for the horizontal line at 0. These
options must be valid for a Line2D object.
vlines_kwargs is used to pass additional optional arguments to the
vertical lines connecting each autocorrelation to the axis. These options
must be valid for a LineCollection object.
References
----------
[1] Brockwell and Davis, 1987. Time Series Theory and Methods
[2] Brockwell and Davis, 2010. Introduction to Time Series and
Forecasting, 2nd edition.
Examples
--------
>>> import pandas as pd
>>> import matplotlib.pyplot as plt
>>> import statsmodels.api as sm
>>> dta = sm.datasets.sunspots.load_pandas().data
>>> dta.index = pd.Index(sm.tsa.datetools.dates_from_range('1700', '2008'))
>>> del dta["YEAR"]
>>> sm.graphics.tsa.plot_acf(dta.values.squeeze(), lags=40)
>>> plt.show()
.. plot:: plots/graphics_tsa_plot_acf.py
"""
fig, ax = utils.create_mpl_ax(ax)
lags, nlags, irregular = _prepare_data_corr_plot(x, lags, zero)
vlines_kwargs = {} if vlines_kwargs is None else vlines_kwargs
confint = None
# acf has different return type based on alpha
acf_x = acf(
x,
nlags=nlags,
alpha=alpha,
fft=fft,
bartlett_confint=bartlett_confint,
adjusted=adjusted,
missing=missing,
)
if alpha is not None:
acf_x, confint = acf_x[:2]
_plot_corr(
ax,
title,
acf_x,
confint,
lags,
irregular,
use_vlines,
vlines_kwargs,
auto_ylims=auto_ylims,
**kwargs,
)
return fig
def plot_pacf(
x,
ax=None,
lags=None,
alpha=0.05,
method="ywm",
use_vlines=True,
title="Partial Autocorrelation",
zero=True,
vlines_kwargs=None,
**kwargs,
):
"""
Plot the partial autocorrelation function
Parameters
----------
x : array_like
Array of time-series values
ax : AxesSubplot, optional
If given, this subplot is used to plot in instead of a new figure being
created.
lags : {int, array_like}, optional
An int or array of lag values, used on horizontal axis. Uses
np.arange(lags) when lags is an int. If not provided,
``lags=np.arange(len(corr))`` is used.
alpha : float, optional
If a number is given, the confidence intervals for the given level are
returned. For instance if alpha=.05, 95 % confidence intervals are
returned where the standard deviation is computed according to
1/sqrt(len(x))
method : str
Specifies which method for the calculations to use:
- "ywm" or "ywmle" : Yule-Walker without adjustment. Default.
- "yw" or "ywadjusted" : Yule-Walker with sample-size adjustment in
denominator for acovf. Default.
- "ols" : regression of time series on lags of it and on constant.
- "ols-inefficient" : regression of time series on lags using a single
common sample to estimate all pacf coefficients.
- "ols-adjusted" : regression of time series on lags with a bias
adjustment.
- "ld" or "ldadjusted" : Levinson-Durbin recursion with bias
correction.
- "ldb" or "ldbiased" : Levinson-Durbin recursion without bias
correction.
use_vlines : bool, optional
If True, vertical lines and markers are plotted.
If False, only markers are plotted. The default marker is 'o'; it can
be overridden with a ``marker`` kwarg.
title : str, optional
Title to place on plot. Default is 'Partial Autocorrelation'
zero : bool, optional
Flag indicating whether to include the 0-lag autocorrelation.
Default is True.
vlines_kwargs : dict, optional
Optional dictionary of keyword arguments that are passed to vlines.
**kwargs : kwargs, optional
Optional keyword arguments that are directly passed on to the
Matplotlib ``plot`` and ``axhline`` functions.
Returns
-------
Figure
If `ax` is None, the created figure. Otherwise the figure to which
`ax` is connected.
See Also
--------
matplotlib.pyplot.xcorr
matplotlib.pyplot.acorr
Notes
-----
Plots lags on the horizontal and the correlations on vertical axis.
Adapted from matplotlib's `xcorr`.
Data are plotted as ``plot(lags, corr, **kwargs)``
kwargs is used to pass matplotlib optional arguments to both the line
tracing the autocorrelations and for the horizontal line at 0. These
options must be valid for a Line2D object.
vlines_kwargs is used to pass additional optional arguments to the
vertical lines connecting each autocorrelation to the axis. These options
must be valid for a LineCollection object.
Examples
--------
>>> import pandas as pd
>>> import matplotlib.pyplot as plt
>>> import statsmodels.api as sm
>>> dta = sm.datasets.sunspots.load_pandas().data
>>> dta.index = pd.Index(sm.tsa.datetools.dates_from_range('1700', '2008'))
>>> del dta["YEAR"]
>>> sm.graphics.tsa.plot_pacf(dta.values.squeeze(), lags=40, method="ywm")
>>> plt.show()
.. plot:: plots/graphics_tsa_plot_pacf.py
"""
fig, ax = utils.create_mpl_ax(ax)
vlines_kwargs = {} if vlines_kwargs is None else vlines_kwargs
lags, nlags, irregular = _prepare_data_corr_plot(x, lags, zero)
confint = None
if alpha is None:
acf_x = pacf(x, nlags=nlags, alpha=alpha, method=method)
else:
acf_x, confint = pacf(x, nlags=nlags, alpha=alpha, method=method)
_plot_corr(
ax,
title,
acf_x,
confint,
lags,
irregular,
use_vlines,
vlines_kwargs,
**kwargs,
)
return fig
def plot_ccf(
x,
y,
*,
ax=None,
lags=None,
negative_lags=False,
alpha=0.05,
use_vlines=True,
adjusted=False,
fft=False,
title="Cross-correlation",
auto_ylims=False,
vlines_kwargs=None,
**kwargs,
):
"""
Plot the cross-correlation function
Correlations between ``x`` and the lags of ``y`` are calculated.
The lags are shown on the horizontal axis and the correlations
on the vertical axis.
Parameters
----------
x, y : array_like
Arrays of time-series values.
ax : AxesSubplot, optional
If given, this subplot is used to plot in, otherwise a new figure with
one subplot is created.
lags : {int, array_like}, optional
An int or array of lag values, used on the horizontal axis. Uses
``np.arange(lags)`` when lags is an int. If not provided,
``lags=np.arange(len(corr))`` is used.
negative_lags: bool, optional
If True, negative lags are shown on the horizontal axis.
alpha : scalar, optional
If a number is given, the confidence intervals for the given level are
plotted, e.g. if alpha=.05, 95 % confidence intervals are shown.
If None, confidence intervals are not shown on the plot.
use_vlines : bool, optional
If True, shows vertical lines and markers for the correlation values.
If False, only shows markers. The default marker is 'o'; it can
be overridden with a ``marker`` kwarg.
adjusted : bool
If True, then denominators for cross-correlations are n-k, otherwise n.
fft : bool, optional
If True, computes the CCF via FFT.
title : str, optional
Title to place on plot. Default is 'Cross-correlation'.
auto_ylims : bool, optional
If True, adjusts automatically the vertical axis limits to CCF values.
vlines_kwargs : dict, optional
Optional dictionary of keyword arguments that are passed to vlines.
**kwargs : kwargs, optional
Optional keyword arguments that are directly passed on to the
Matplotlib ``plot`` and ``axhline`` functions.
Returns
-------
Figure
The figure where the plot is drawn. This is either an existing figure
if the `ax` argument is provided, or a newly created figure
if `ax` is None.
See Also
--------
statsmodels.graphics.tsaplots.plot_acf
Examples
--------
>>> import pandas as pd
>>> import matplotlib.pyplot as plt
>>> import statsmodels.api as sm
>>> dta = sm.datasets.macrodata.load_pandas().data
>>> diffed = dta.diff().dropna()
>>> sm.graphics.tsa.plot_ccf(diffed["unemp"], diffed["infl"])
>>> plt.show()
"""
fig, ax = utils.create_mpl_ax(ax)
lags, nlags, irregular = _prepare_data_corr_plot(x, lags, True)
vlines_kwargs = {} if vlines_kwargs is None else vlines_kwargs
if negative_lags:
lags = -lags
ccf_res = ccf(
x, y, adjusted=adjusted, fft=fft, alpha=alpha, nlags=nlags + 1
)
if alpha is not None:
ccf_xy, confint = ccf_res
else:
ccf_xy = ccf_res
confint = None
_plot_corr(
ax,
title,
ccf_xy,
confint,
lags,
irregular,
use_vlines,
vlines_kwargs,
auto_ylims=auto_ylims,
skip_lag0_confint=False,
**kwargs,
)
return fig
def plot_accf_grid(
x,
*,
varnames=None,
fig=None,
lags=None,
negative_lags=True,
alpha=0.05,
use_vlines=True,
adjusted=False,
fft=False,
missing="none",
zero=True,
auto_ylims=False,
bartlett_confint=False,
vlines_kwargs=None,
**kwargs,
):
"""
Plot auto/cross-correlation grid
Plots lags on the horizontal axis and the correlations
on the vertical axis of each graph.
Parameters
----------
x : array_like
2D array of time-series values: rows are observations,
columns are variables.
varnames: sequence of str, optional
Variable names to use in plot titles. If ``x`` is a pandas dataframe
and ``varnames`` is provided, it overrides the column names
of the dataframe. If ``varnames`` is not provided and ``x`` is not
a dataframe, variable names ``x[0]``, ``x[1]``, etc. are generated.
fig : Matplotlib figure instance, optional
If given, this figure is used to plot in, otherwise a new figure
is created.
lags : {int, array_like}, optional
An int or array of lag values, used on horizontal axes. Uses
``np.arange(lags)`` when lags is an int. If not provided,
``lags=np.arange(len(corr))`` is used.
negative_lags: bool, optional
If True, negative lags are shown on the horizontal axes of plots
below the main diagonal.
alpha : scalar, optional
If a number is given, the confidence intervals for the given level are
plotted, e.g. if alpha=.05, 95 % confidence intervals are shown.
If None, confidence intervals are not shown on the plot.
use_vlines : bool, optional
If True, shows vertical lines and markers for the correlation values.
If False, only shows markers. The default marker is 'o'; it can
be overridden with a ``marker`` kwarg.
adjusted : bool
If True, then denominators for correlations are n-k, otherwise n.
fft : bool, optional
If True, computes the ACF via FFT.
missing : str, optional
A string in ['none', 'raise', 'conservative', 'drop'] specifying how
NaNs are to be treated.
zero : bool, optional
Flag indicating whether to include the 0-lag autocorrelations
(which are always equal to 1). Default is True.
auto_ylims : bool, optional
If True, adjusts automatically the vertical axis limits
to correlation values.
bartlett_confint : bool, default False
If True, use Bartlett's formula to calculate confidence intervals
in auto-correlation plots. See the description of ``plot_acf`` for
details. This argument does not affect cross-correlation plots.
vlines_kwargs : dict, optional
Optional dictionary of keyword arguments that are passed to vlines.
**kwargs : kwargs, optional
Optional keyword arguments that are directly passed on to the
Matplotlib ``plot`` and ``axhline`` functions.
Returns
-------
Figure
If `fig` is None, the created figure. Otherwise, `fig` is returned.
Plots on the grid show the cross-correlation of the row variable
with the lags of the column variable.
See Also
--------
statsmodels.graphics.tsaplots
Examples
--------
>>> import pandas as pd
>>> import matplotlib.pyplot as plt
>>> import statsmodels.api as sm
>>> dta = sm.datasets.macrodata.load_pandas().data
>>> diffed = dta.diff().dropna()
>>> sm.graphics.tsa.plot_accf_grid(diffed[["unemp", "infl"]])
>>> plt.show()
"""
from statsmodels.tools.data import _is_using_pandas
array_like(x, "x", ndim=2)
m = x.shape[1]
fig = utils.create_mpl_fig(fig)
gs = fig.add_gridspec(m, m)
if _is_using_pandas(x, None):
varnames = varnames or list(x.columns)
def get_var(i):
return x.iloc[:, i]
else:
varnames = varnames or [f'x[{i}]' for i in range(m)]
x = np.asarray(x)
def get_var(i):
return x[:, i]
for i in range(m):
for j in range(m):
ax = fig.add_subplot(gs[i, j])
if i == j:
plot_acf(
get_var(i),
ax=ax,
title=f'ACF({varnames[i]})',
lags=lags,
alpha=alpha,
use_vlines=use_vlines,
adjusted=adjusted,
fft=fft,
missing=missing,
zero=zero,
auto_ylims=auto_ylims,
bartlett_confint=bartlett_confint,
vlines_kwargs=vlines_kwargs,
**kwargs,
)
else:
plot_ccf(
get_var(i),
get_var(j),
ax=ax,
title=f'CCF({varnames[i]}, {varnames[j]})',
lags=lags,
negative_lags=negative_lags and i > j,
alpha=alpha,
use_vlines=use_vlines,
adjusted=adjusted,
fft=fft,
auto_ylims=auto_ylims,
vlines_kwargs=vlines_kwargs,
**kwargs,
)
return fig
def seasonal_plot(grouped_x, xticklabels, ylabel=None, ax=None):
"""
Consider using one of month_plot or quarter_plot unless you need
irregular plotting.
Parameters
----------
grouped_x : iterable of DataFrames
Should be a GroupBy object (or similar pair of group_names and groups
as DataFrames) with a DatetimeIndex or PeriodIndex
xticklabels : list of str
List of season labels, one for each group.
ylabel : str
Lable for y axis
ax : AxesSubplot, optional
If given, this subplot is used to plot in instead of a new figure being
created.
"""
fig, ax = utils.create_mpl_ax(ax)
start = 0
ticks = []
for season, df in grouped_x:
df = df.copy() # or sort balks for series. may be better way
df.sort_index()
nobs = len(df)
x_plot = np.arange(start, start + nobs)
ticks.append(x_plot.mean())
ax.plot(x_plot, df.values, "k")
ax.hlines(
df.values.mean(), x_plot[0], x_plot[-1], colors="r", linewidth=3
)
start += nobs
ax.set_xticks(ticks)
ax.set_xticklabels(xticklabels)
ax.set_ylabel(ylabel)
ax.margins(0.1, 0.05)
return fig
def month_plot(x, dates=None, ylabel=None, ax=None):
"""
Seasonal plot of monthly data.
Parameters
----------
x : array_like
Seasonal data to plot. If dates is None, x must be a pandas object
with a PeriodIndex or DatetimeIndex with a monthly frequency.
dates : array_like, optional
If `x` is not a pandas object, then dates must be supplied.
ylabel : str, optional
The label for the y-axis. Will attempt to use the `name` attribute
of the Series.
ax : Axes, optional
Existing axes instance.
Returns
-------
Figure
If `ax` is provided, the Figure instance attached to `ax`. Otherwise
a new Figure instance.
Examples
--------
>>> import statsmodels.api as sm
>>> import pandas as pd
>>> dta = sm.datasets.elnino.load_pandas().data
>>> dta['YEAR'] = dta.YEAR.astype(int).astype(str)
>>> dta = dta.set_index('YEAR').T.unstack()
>>> dates = pd.to_datetime(list(map(lambda x: '-'.join(x) + '-1',
... dta.index.values)))
>>> dta.index = pd.DatetimeIndex(dates, freq='MS')
>>> fig = sm.graphics.tsa.month_plot(dta)
.. plot:: plots/graphics_tsa_month_plot.py
"""
if dates is None:
from statsmodels.tools.data import _check_period_index
_check_period_index(x, freq="M")
else:
x = pd.Series(x, index=pd.PeriodIndex(dates, freq="M"))
# there's no zero month
xticklabels = list(calendar.month_abbr)[1:]
return seasonal_plot(
x.groupby(lambda y: y.month), xticklabels, ylabel=ylabel, ax=ax
)
def quarter_plot(x, dates=None, ylabel=None, ax=None):
"""
Seasonal plot of quarterly data
Parameters
----------
x : array_like
Seasonal data to plot. If dates is None, x must be a pandas object
with a PeriodIndex or DatetimeIndex with a monthly frequency.
dates : array_like, optional
If `x` is not a pandas object, then dates must be supplied.
ylabel : str, optional
The label for the y-axis. Will attempt to use the `name` attribute
of the Series.
ax : matplotlib.axes, optional
Existing axes instance.
Returns
-------
Figure
If `ax` is provided, the Figure instance attached to `ax`. Otherwise
a new Figure instance.
Examples
--------
>>> import statsmodels.api as sm
>>> import pandas as pd
>>> dta = sm.datasets.elnino.load_pandas().data
>>> dta['YEAR'] = dta.YEAR.astype(int).astype(str)
>>> dta = dta.set_index('YEAR').T.unstack()
>>> dates = pd.to_datetime(list(map(lambda x: '-'.join(x) + '-1',
... dta.index.values)))
>>> dta.index = dates.to_period('Q')
>>> fig = sm.graphics.tsa.quarter_plot(dta)
.. plot:: plots/graphics_tsa_quarter_plot.py
"""
if dates is None:
from statsmodels.tools.data import _check_period_index
_check_period_index(x, freq="Q")
else:
x = pd.Series(x, index=pd.PeriodIndex(dates, freq="Q"))
xticklabels = ["q1", "q2", "q3", "q4"]
return seasonal_plot(
x.groupby(lambda y: y.quarter), xticklabels, ylabel=ylabel, ax=ax
)
def plot_predict(
result,
start=None,
end=None,
dynamic=False,
alpha=0.05,
ax=None,
**predict_kwargs,
):
"""
Parameters
----------
result : Result
Any model result supporting ``get_prediction``.
start : int, str, or datetime, optional
Zero-indexed observation number at which to start forecasting,
i.e., the first forecast is start. Can also be a date string to
parse or a datetime type. Default is the the zeroth observation.
end : int, str, or datetime, optional
Zero-indexed observation number at which to end forecasting, i.e.,
the last forecast is end. Can also be a date string to
parse or a datetime type. However, if the dates index does not
have a fixed frequency, end must be an integer index if you
want out of sample prediction. Default is the last observation in
the sample.
dynamic : bool, int, str, or datetime, optional
Integer offset relative to `start` at which to begin dynamic
prediction. Can also be an absolute date string to parse or a
datetime type (these are not interpreted as offsets).
Prior to this observation, true endogenous values will be used for
prediction; starting with this observation and continuing through
the end of prediction, forecasted endogenous values will be used
instead.
alpha : {float, None}
The tail probability not covered by the confidence interval. Must
be in (0, 1). Confidence interval is constructed assuming normally
distributed shocks. If None, figure will not show the confidence
interval.
ax : AxesSubplot
matplotlib Axes instance to use
**predict_kwargs
Any additional keyword arguments to pass to ``result.get_prediction``.
Returns
-------
Figure
matplotlib Figure containing the prediction plot
"""
from statsmodels.graphics.utils import _import_mpl, create_mpl_ax
_ = _import_mpl()
fig, ax = create_mpl_ax(ax)
from statsmodels.tsa.base.prediction import PredictionResults
# use predict so you set dates
pred: PredictionResults = result.get_prediction(
start=start, end=end, dynamic=dynamic, **predict_kwargs
)
mean = pred.predicted_mean
if isinstance(mean, (pd.Series, pd.DataFrame)):
x = mean.index
mean.plot(ax=ax, label="forecast")
else:
x = np.arange(mean.shape[0])
ax.plot(x, mean, label="forecast")
if alpha is not None:
label = f"{1-alpha:.0%} confidence interval"
ci = pred.conf_int(alpha)
conf_int = np.asarray(ci)
ax.fill_between(
x,
conf_int[:, 0],
conf_int[:, 1],
color="gray",
alpha=0.5,
label=label,
)
ax.legend(loc="best")
return fig