[Debian-med-packaging] Bug#1053265: dipy: test_icm_square test fails since exact equality used with floating point numbers

[Drew Parsons]

Source: dipy
Version: 1.7.0-2
Severity: serious
Justification: debci

h5py 3.9.0 is triggering an error in dipy debci tests,
https://ci.debian.net/data/autopkgtest/testing/amd64/d/dipy/38279462/log.gz

However from the error log, it's not clear that the problem is
directly related to h5py.  An exact [in]equality test is failing
between floating point numbers.

The error log is:

1967s _______________________________ test_icm_square ________________________________
1967s 
1967s     def test_icm_square():
1967s     
1967s         com = ConstantObservationModel()
1967s         icm = IteratedConditionalModes()
1967s     
1967s         initial_segmentation = square
1967s     
1967s         mu, sigma = com.seg_stats(square_1, initial_segmentation,
1967s                                   nclasses)
1967s         sigmasq = sigma ** 2
1967s         npt.assert_(mu[0] >= 0.0)
1967s         npt.assert_(mu[1] >= 0.0)
1967s         npt.assert_(mu[2] >= 0.0)
1967s         npt.assert_(mu[3] >= 0.0)
1967s         npt.assert_(sigmasq[0] >= 0.0)
1967s         npt.assert_(sigmasq[1] >= 0.0)
1967s         npt.assert_(sigmasq[2] >= 0.0)
1967s         npt.assert_(sigmasq[3] >= 0.0)
1967s     
1967s         negll = com.negloglikelihood(square_1, mu, sigmasq, nclasses)
1967s     
1967s         final_segmentation_1 = np.empty_like(square_1)
1967s         final_segmentation_2 = np.empty_like(square_1)
1967s     
1967s         beta = 0.0
1967s     
1967s         for i in range(max_iter):
1967s     
1967s             print('\n')
1967s             print('>> Iteration: ' + str(i))
1967s             print('\n')
1967s     
1967s             final_segmentation_1, energy_1 = icm.icm_ising(negll, beta,
1967s                                                            initial_segmentation)
1967s             initial_segmentation = final_segmentation_1
1967s     
1967s         beta = 2
1967s         initial_segmentation = square
1967s     
1967s         for j in range(max_iter):
1967s     
1967s             print('\n')
1967s             print('>> Iteration: ' + str(j))
1967s             print('\n')
1967s     
1967s             final_segmentation_2, energy_2 = icm.icm_ising(negll, beta,
1967s                                                            initial_segmentation)
1967s             initial_segmentation = final_segmentation_2
1967s     
1967s         difference_map = np.abs(final_segmentation_1 - final_segmentation_2)
1967s >       npt.assert_(np.abs(np.sum(difference_map)) != 0)
1967s E       AssertionError
1967s 
1967s dipy/segment/tests/test_mrf.py:370: AssertionError


I'm assumung final_segmentation is floating point, not integer.
Correct me if that's wrong. In general exact equality of floating
point numbers should always be expected to fail. The test should be
something like
   npt.assert_( not np.isclose( np.abs(np.sum(difference_map)), 0 ) )
   

If final_segmentation is an integer then of course it's a different
problem.