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Time-Series-Analysis/venv/lib/python3.11/site-packages/pmdarima/arima/tests/test_approx.py
2025-08-01 04:33:03 -04:00

87 lines
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Python

# Test the approximation function
from pmdarima.arima.approx import approx, _regularize
from pmdarima.utils.array import c
from pmdarima.arima.stationarity import ADFTest
from numpy.testing import assert_array_almost_equal
import numpy as np
import pytest
table = c(0.216, 0.176, 0.146, 0.119)
tablep = c(0.01, 0.025, 0.05, 0.10)
stat = 1.01
def test_regularize():
x, y = c(0.5, 0.5, 1.0, 1.5), c(1, 2, 3, 4)
x, y = _regularize(x, y, 'mean')
assert_array_almost_equal(x, np.array([0.5, 1.0, 1.5]))
assert_array_almost_equal(y, np.array([1.5, 3.0, 4.0]))
def test_approx_rule1():
# for rule = 1
x, y = approx(table, tablep, stat, rule=1)
assert_array_almost_equal(x, c(1.01))
assert_array_almost_equal(y, c(np.nan))
def test_approx_rule2():
# for rule = 2
x, y = approx(table, tablep, stat, rule=2)
assert_array_almost_equal(x, c(1.01))
assert_array_almost_equal(y, c(0.01))
@pytest.mark.parametrize(
'kwargs', [
# fails for length differences
dict(x=[1, 2, 3], y=[1, 2], xout=1.0),
# fails for bad string
dict(x=table, y=table, xout=1.0, method='bad-string'),
# fails for bad length
dict(x=[], y=[], xout=[], ties='mean'),
# fails for bad length
dict(x=[], y=[], xout=[], method='constant'),
# fails for linear when < 2 samples
dict(x=[1], y=[1], xout=[], method='linear', ties='ordered'),
# fails for bad length
dict(x=[], y=[], xout=[], method='constant'),
]
)
def test_corner_errors(kwargs):
with pytest.raises(ValueError):
approx(**kwargs)
def test_valid_corner():
# *doesn't* fail for constant when < 2 samples
approx(x=[1], y=[1], xout=[], method='constant', ties='ordered')
def test_approx_precision():
# Test an example from R vs. Python to compare the expected values and
# make sure we get as close as possible. This is from an ADFTest where k=1
# and x=austres
tableipl = np.array([[-4.0664],
[-3.7468],
[-3.462],
[-3.1572],
[-1.2128],
[-0.8928],
[-0.6104],
[-0.2704]])
_, interpol = approx(tableipl, ADFTest.tablep, xout=-1.337233, rule=2)
assert np.allclose(interpol, 0.84880354) # in R we get 0.8488036