craftbeerpi4-pione/venv/lib/python3.8/site-packages/pandas/tests/window/test_ewm.py
2021-01-30 22:29:33 +01:00

129 lines
4 KiB
Python

import numpy as np
import pytest
from pandas.errors import UnsupportedFunctionCall
from pandas import DataFrame, DatetimeIndex, Series, date_range
import pandas._testing as tm
from pandas.core.window import ExponentialMovingWindow
def test_doc_string():
df = DataFrame({"B": [0, 1, 2, np.nan, 4]})
df
df.ewm(com=0.5).mean()
def test_constructor(which):
c = which.ewm
# valid
c(com=0.5)
c(span=1.5)
c(alpha=0.5)
c(halflife=0.75)
c(com=0.5, span=None)
c(alpha=0.5, com=None)
c(halflife=0.75, alpha=None)
# not valid: mutually exclusive
msg = "comass, span, halflife, and alpha are mutually exclusive"
with pytest.raises(ValueError, match=msg):
c(com=0.5, alpha=0.5)
with pytest.raises(ValueError, match=msg):
c(span=1.5, halflife=0.75)
with pytest.raises(ValueError, match=msg):
c(alpha=0.5, span=1.5)
# not valid: com < 0
msg = "comass must satisfy: comass >= 0"
with pytest.raises(ValueError, match=msg):
c(com=-0.5)
# not valid: span < 1
msg = "span must satisfy: span >= 1"
with pytest.raises(ValueError, match=msg):
c(span=0.5)
# not valid: halflife <= 0
msg = "halflife must satisfy: halflife > 0"
with pytest.raises(ValueError, match=msg):
c(halflife=0)
# not valid: alpha <= 0 or alpha > 1
msg = "alpha must satisfy: 0 < alpha <= 1"
for alpha in (-0.5, 1.5):
with pytest.raises(ValueError, match=msg):
c(alpha=alpha)
@pytest.mark.parametrize("method", ["std", "mean", "var"])
def test_numpy_compat(method):
# see gh-12811
e = ExponentialMovingWindow(Series([2, 4, 6]), alpha=0.5)
msg = "numpy operations are not valid with window objects"
with pytest.raises(UnsupportedFunctionCall, match=msg):
getattr(e, method)(1, 2, 3)
with pytest.raises(UnsupportedFunctionCall, match=msg):
getattr(e, method)(dtype=np.float64)
def test_ewma_times_not_datetime_type():
msg = r"times must be datetime64\[ns\] dtype."
with pytest.raises(ValueError, match=msg):
Series(range(5)).ewm(times=np.arange(5))
def test_ewma_times_not_same_length():
msg = "times must be the same length as the object."
with pytest.raises(ValueError, match=msg):
Series(range(5)).ewm(times=np.arange(4).astype("datetime64[ns]"))
def test_ewma_halflife_not_correct_type():
msg = "halflife must be a string or datetime.timedelta object"
with pytest.raises(ValueError, match=msg):
Series(range(5)).ewm(halflife=1, times=np.arange(5).astype("datetime64[ns]"))
def test_ewma_halflife_without_times(halflife_with_times):
msg = "halflife can only be a timedelta convertible argument if times is not None."
with pytest.raises(ValueError, match=msg):
Series(range(5)).ewm(halflife=halflife_with_times)
@pytest.mark.parametrize(
"times",
[
np.arange(10).astype("datetime64[D]").astype("datetime64[ns]"),
date_range("2000", freq="D", periods=10),
date_range("2000", freq="D", periods=10).tz_localize("UTC"),
"time_col",
],
)
@pytest.mark.parametrize("min_periods", [0, 2])
def test_ewma_with_times_equal_spacing(halflife_with_times, times, min_periods):
halflife = halflife_with_times
data = np.arange(10.0)
data[::2] = np.nan
df = DataFrame({"A": data, "time_col": date_range("2000", freq="D", periods=10)})
result = df.ewm(halflife=halflife, min_periods=min_periods, times=times).mean()
expected = df.ewm(halflife=1.0, min_periods=min_periods).mean()
tm.assert_frame_equal(result, expected)
def test_ewma_with_times_variable_spacing(tz_aware_fixture):
tz = tz_aware_fixture
halflife = "23 days"
times = DatetimeIndex(
["2020-01-01", "2020-01-10T00:04:05", "2020-02-23T05:00:23"]
).tz_localize(tz)
data = np.arange(3)
df = DataFrame(data)
result = df.ewm(halflife=halflife, times=times).mean()
expected = DataFrame([0.0, 0.5674161888241773, 1.545239952073459])
tm.assert_frame_equal(result, expected)