My guess is a precision issue with inequality comparison, but don't
know why only on your machine so far.
Can you try to change delta to 1 + 1e-10 in the test?
line 88 in test_lowess.py
actual_lowess_del1 = lowess(test_data['y'], test_data['x'], frac =
0.1, delta = 1.0 + 1e-10)
the tests still pass for me if I do this change
E:\tmp>nosetests --pdb-failures
e:\josef\eclipsegworkspace\statsmodels-git\statsmodels-all-new2\statsmodels\statsmodels\nonparametric\tests\test_lowess.py
C:\Python26\Scripts\nosetests-script.py:5: UserWarning: Module
pkg_resources was already imported from
C:\Python26\lib\site-packages\pkg_resources.pyc, but
c:\python26\lib\site-packages\distribute-0.6.24-py2.6.egg is being
added to sys.path
from pkg_resources import load_entry_point
C:\Python26\Scripts\nosetests-script.py:5: UserWarning: Module site
was already imported from C:\Python26\lib\site.pyc, but
c:\python26\lib\site-packages\distribute-0.6.24-py2.6.egg is being
added to sys.path
from pkg_resources import load_entry_point
> c:\python26\lib\site-packages\numpy\testing\utils.py(618)assert_array_compare()
-> raise AssertionError(msg)
precision is much higher that decimal 7 on my computer
(Pdb) import numpy as np
(Pdb) np.max(np.abs(y - x))
5.5422333389287814e-13
(Pdb) np.max(np.abs(x / y - 1))
1.3222756223285614e-12
(Pdb) u
> c:\python26\lib\site-packages\numpy\testing\utils.py(774)assert_array_almost_equal()
-> header='Arrays are not almost equal')
(Pdb) u
> c:\python26\lib\site-packages\numpy\testing\utils.py(447)assert_almost_equal()
-> return assert_array_almost_equal(actual, desired, decimal, err_msg)
(Pdb) u
> e:\josef\eclipsegworkspace\statsmodels-git\statsmodels-all-new2\statsmodels\statsmodels\nonparametric\tests\test_lowess.py(92)test_delta()
-> assert_almost_equal(expected_lowess_del1, actual_lowess_del1,
decimal = 15) #testdec)
(Pdb) np.min(np.abs(np.diff(expected_lowess_del1[:,0]) - 1))
0.0
delta increments for delta=1.0 fall exactly at the observations.
Josef