[MRG+1] Make TSNE trustworthiness test more robust (#9808)

ogrisel · jnothman · commit 6c99d797d7c7 · 2017-09-24T21:33:10.000+10:00
Platform specific rounding errors can make the t-SNE algorithm
converge to varying quality results especially on small datasets
as done in this test.

We therefore need a lower threshold to account for that
variability.
diff --git a/sklearn/manifold/tests/test_t_sne.py b/sklearn/manifold/tests/test_t_sne.py
@@ -244,9 +244,9 @@ def test_preserve_trustworthiness_approximately():
                         method=method)
             X_embedded = tsne.fit_transform(X)
             t = trustworthiness(X, X_embedded, n_neighbors=1)
-            assert_greater(t, 0.9, msg='Trustworthiness={:0.3f} < 0.9 '
-                                       'for method={} and '
-                                       'init={}'.format(t, method, init))
+            assert_greater(t, 0.85, msg='Trustworthiness={:0.3f} < 0.85 '
+                                        'for method={} and '
+                                        'init={}'.format(t, method, init))
 
 
 def test_optimization_minimizes_kl_divergence():
