Relax IVFFlatDedup test

Summary:
This diff relaxes some IVFFlatDedup tests where distances are slighlty different over runs.
Should fix

https://app.circleci.com/pipelines/github/facebookresearch/faiss/4709/workflows/8c8213bf-8fe0-4c4e-9a7d-991f44bf1010/jobs/25551

https://app.circleci.com/pipelines/github/facebookresearch/faiss/4709/workflows/8c8213bf-8fe0-4c4e-9a7d-991f44bf1010/jobs/25547

Differential Revision: D49732349

contrib/evaluation.py

@@ -227,7 +227,8 @@ def compute_PR_for(q):
 # They are intended for use in tests
 
 def check_ref_knn_with_draws(Dref, Iref, Dnew, Inew):
- """ test that knn search results are identical, raise if not """
+ """ test that knn search results are identical, with possible ties.
+ Raise if not. """
  np.testing.assert_array_almost_equal(Dref, Dnew, decimal=5)
  # here we have to be careful because of draws
  testcase = unittest.TestCase() # because it makes nice error messages

tests/test_index_composite.py

@@ -17,7 +17,7 @@
 from common_faiss_tests import get_dataset_2
 from faiss.contrib.datasets import SyntheticDataset
 from faiss.contrib.inspect_tools import make_LinearTransform_matrix
-
+from faiss.contrib.evaluation import check_ref_knn_with_draws
 
 class TestRemoveFastScan(unittest.TestCase):
  def do_test(self, ntotal, removed):
@@ -430,12 +430,6 @@ def test_mmappedIO_pretrans(self):
 
 class TestIVFFlatDedup(unittest.TestCase):
 
- def normalize_res(self, D, I):
- dmax = D[-1]
- res = [(d, i) for d, i in zip(D, I) if d < dmax]
- res.sort()
- return res
-
  def test_dedup(self):
  d = 10
  nb = 1000
@@ -471,10 +465,7 @@ def test_dedup(self):
  Dref, Iref = index_ref.search(xq, 20)
  Dnew, Inew = index_new.search(xq, 20)
 
- for i in range(nq):
- ref = self.normalize_res(Dref[i], Iref[i])
- new = self.normalize_res(Dnew[i], Inew[i])
- assert ref == new
+ check_ref_knn_with_draws(Dref, Iref, Dnew, Inew)
 
  # test I/O
  fd, tmpfile = tempfile.mkstemp()
@@ -487,10 +478,7 @@ def test_dedup(self):
  os.unlink(tmpfile)
  Dst, Ist = index_st.search(xq, 20)
 
- for i in range(nq):
- new = self.normalize_res(Dnew[i], Inew[i])
- st = self.normalize_res(Dst[i], Ist[i])
- assert st == new
+ check_ref_knn_with_draws(Dnew, Inew, Dst, Ist)
 
  # test remove
  toremove = np.hstack((np.arange(3, 1000, 5), np.arange(850, 950)))
@@ -501,10 +489,7 @@ def test_dedup(self):
  Dref, Iref = index_ref.search(xq, 20)
  Dnew, Inew = index_new.search(xq, 20)
 
- for i in range(nq):
- ref = self.normalize_res(Dref[i], Iref[i])
- new = self.normalize_res(Dnew[i], Inew[i])
- assert ref == new
+ check_ref_knn_with_draws(Dref, Iref, Dnew, Inew)
 
 
 class TestSerialize(unittest.TestCase):