Fixed database typo and removed unnecessary class identifier.

venv/Lib/site-packages/scipy/stats/tests/test_fit.py

@@ -0,0 +1,120 @@
+import os
+
+import numpy as np
+from numpy.testing import assert_allclose, suppress_warnings
+import pytest
+from scipy import stats
+
+from .test_continuous_basic import distcont
+
+# this is not a proper statistical test for convergence, but only
+# verifies that the estimate and true values don't differ by too much
+
+fit_sizes = [1000, 5000]  # sample sizes to try
+
+thresh_percent = 0.25  # percent of true parameters for fail cut-off
+thresh_min = 0.75  # minimum difference estimate - true to fail test
+
+failing_fits = [
+        'burr',
+        'chi2',
+        'gausshyper',
+        'genexpon',
+        'gengamma',
+        'kappa4',
+        'ksone',
+        'kstwo',
+        'mielke',
+        'ncf',
+        'ncx2',
+        'pearson3',
+        'powerlognorm',
+        'truncexpon',
+        'tukeylambda',
+        'vonmises',
+        'wrapcauchy',
+        'levy_stable',
+        'trapz'
+]
+
+# Don't run the fit test on these:
+skip_fit = [
+    'erlang',  # Subclass of gamma, generates a warning.
+]
+
+
+def cases_test_cont_fit():
+    # this tests the closeness of the estimated parameters to the true
+    # parameters with fit method of continuous distributions
+    # Note: is slow, some distributions don't converge with sample size <= 10000
+    for distname, arg in distcont:
+        if distname not in skip_fit:
+            yield distname, arg
+
+
+@pytest.mark.slow
+@pytest.mark.parametrize('distname,arg', cases_test_cont_fit())
+def test_cont_fit(distname, arg):
+    if distname in failing_fits:
+        # Skip failing fits unless overridden
+        try:
+            xfail = not int(os.environ['SCIPY_XFAIL'])
+        except Exception:
+            xfail = True
+        if xfail:
+            msg = "Fitting %s doesn't work reliably yet" % distname
+            msg += " [Set environment variable SCIPY_XFAIL=1 to run this test nevertheless.]"
+            pytest.xfail(msg)
+
+    distfn = getattr(stats, distname)
+
+    truearg = np.hstack([arg, [0.0, 1.0]])
+    diffthreshold = np.max(np.vstack([truearg*thresh_percent,
+                                      np.full(distfn.numargs+2, thresh_min)]),
+                           0)
+
+    for fit_size in fit_sizes:
+        # Note that if a fit succeeds, the other fit_sizes are skipped
+        np.random.seed(1234)
+
+        with np.errstate(all='ignore'), suppress_warnings() as sup:
+            sup.filter(category=DeprecationWarning, message=".*frechet_")
+            rvs = distfn.rvs(size=fit_size, *arg)
+            est = distfn.fit(rvs)  # start with default values
+
+        diff = est - truearg
+
+        # threshold for location
+        diffthreshold[-2] = np.max([np.abs(rvs.mean())*thresh_percent,thresh_min])
+
+        if np.any(np.isnan(est)):
+            raise AssertionError('nan returned in fit')
+        else:
+            if np.all(np.abs(diff) <= diffthreshold):
+                break
+    else:
+        txt = 'parameter: %s\n' % str(truearg)
+        txt += 'estimated: %s\n' % str(est)
+        txt += 'diff     : %s\n' % str(diff)
+        raise AssertionError('fit not very good in %s\n' % distfn.name + txt)
+
+
+def _check_loc_scale_mle_fit(name, data, desired, atol=None):
+    d = getattr(stats, name)
+    actual = d.fit(data)[-2:]
+    assert_allclose(actual, desired, atol=atol,
+                    err_msg='poor mle fit of (loc, scale) in %s' % name)
+
+
+def test_non_default_loc_scale_mle_fit():
+    data = np.array([1.01, 1.78, 1.78, 1.78, 1.88, 1.88, 1.88, 2.00])
+    _check_loc_scale_mle_fit('uniform', data, [1.01, 0.99], 1e-3)
+    _check_loc_scale_mle_fit('expon', data, [1.01, 0.73875], 1e-3)
+
+
+def test_expon_fit():
+    """gh-6167"""
+    data = [0, 0, 0, 0, 2, 2, 2, 2]
+    phat = stats.expon.fit(data, floc=0)
+    assert_allclose(phat, [0, 1.0], atol=1e-3)
+